WO2016193154A1 - External fixation system - Google Patents

External fixation system Download PDF

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Publication number
WO2016193154A1
WO2016193154A1 PCT/EP2016/062028 EP2016062028W WO2016193154A1 WO 2016193154 A1 WO2016193154 A1 WO 2016193154A1 EP 2016062028 W EP2016062028 W EP 2016062028W WO 2016193154 A1 WO2016193154 A1 WO 2016193154A1
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WO
WIPO (PCT)
Prior art keywords
external fixation
rail
posterior
medial
lateral
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2016/062028
Other languages
French (fr)
Inventor
Dan PUTINEANU
Olivier CARTIAUX
Paul ÉTIENNE
Thibaut PAQUET
Thomas DE WALQUE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universite Catholique de Louvain UCL
Cliniques Universitaires Saint Luc
Original Assignee
Universite Catholique de Louvain UCL
Cliniques Universitaires Saint Luc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universite Catholique de Louvain UCL, Cliniques Universitaires Saint Luc filed Critical Universite Catholique de Louvain UCL
Publication of WO2016193154A1 publication Critical patent/WO2016193154A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements for external osteosynthesis, e.g. distractors, contractors
    • A61B17/66—Alignment, compression or distraction mechanisms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements for external osteosynthesis, e.g. distractors, contractors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements for external osteosynthesis, e.g. distractors, contractors
    • A61B17/64—Devices extending alongside the bones to be positioned
    • A61B17/6425—Devices extending alongside the bones to be positioned specially adapted to be fitted across a bone joint
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements for external osteosynthesis, e.g. distractors, contractors
    • A61B17/64—Devices extending alongside the bones to be positioned
    • A61B17/645—Devices extending alongside the bones to be positioned comprising a framework
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements for external osteosynthesis, e.g. distractors, contractors
    • A61B17/62—Ring frames, i.e. devices extending around the bones to be positioned

Definitions

  • the present invention pertains to the field of orthopedics. Especially, this invention relates to an external fixation system, more specifically to an external orthopedic fixation system for intuitive and independent relative translational motions between the frame elements in three directions.
  • Orthopedic external fixation systems are used for stabilization and immobilization of dislocations or joint fractures.
  • External fixators can be used as a primary means of reduction of dislocations and joint fractures or may be used in procedures involving temporary external fixation to stabilize the injury and allow soft tissues to recover and secondary surgical procedure of definitive internal fixation.
  • External fixation systems typically comprise a series of pins or wires, suitable for insertion within bone, externally connected to a rigid frame enabling correction of the alignment of bone segments.
  • external fixators include planar and multi-planar fixators, Ilizarov devices, Taylor spatial frames and similar systems.
  • Planar fixators comprise at least one rod attached with pins above and below a fracture site through one (unilateral) or both (bilateral) side of the bone.
  • Planar frames do not allow multi-planar manipulation after the frame (the rod) is applied.
  • Multi-planar device improves the stability of the device but not as efficiently as Ilizarov devices.
  • Ilizarov devices or similar circular external fixators such as those disclosed in US 4,890,631 or US 2014/0058389, comprise at least two external rings or partial rings externally connected by threaded rods.
  • the frames which encircle the limb, are attached to the bone by crossing trans-osseous wires or half pins. Said device are adapted for use in the method known as the Ilizarov method.
  • Ilizarov or similar devices allows fixation of wires or pins all around the bone.
  • said devices allows mainly relative superoinferior motions between the at least two rings.
  • translation of the central axis of one of the ring towards or away the central axis of each threaded rods can also be achieved.
  • said devices do not allow pure translational motions between the frame elements.
  • the Taylor spatial frame or similar fixators such as those disclosed in US 5,702,389, US 2013/0245625 or US 2014/0276821, comprises two rings connected with six crossed telescopic rods or struts that can be independently lengthened or shortened relative to the rest of the frame. Said devices allow a full six axes of movement. The adjustment of the six independent rods requires a computer application which provides day-by-day treatment plan. Said devices do not allow pure relative translation of the rings and require unlocking of the six rods in order to adjust the relative position of the rings.
  • WO 2014/163591 discloses a fixation system comprising two rings connected by telescopic struts wherein one of the two rings comprises four tangential sled systems enabling movement of the struts by means of threaded rods.
  • WO 2010/104567 discloses an external fixation system comprising first and second planar circular ring elements, each comprising a ring gear, and telescopic struts; wherein the two ends of each strut are not configured to slide along the ring gear of the planar circular ring elements.
  • GB 2101488 describes a fixation system comprising at least two calipers comprising pin holders and at least two distractions bars joining the calipers together; wherein the pin holders are located at the ends of the distractions bars; thereby preventing movement of the distractions bars once pins, penetrating into bone tissue, are secured to the pin holders.
  • the present orthopedic external fixator aims at providing an easy-to-use fixator, implementing simple motion compared to the devices of the prior art. Especially, every joint of the external fixator comprises less than 3 degrees of freedom, for instance a single or 2 degrees of freedom, so that the user may precisely know which motion will be implemented.
  • the present orthopedic external fixator includes means for carrying out at least pure relative translations between the frame elements, independently in three directions.
  • the present invention can be used by surgeons with basic training in orthopedic fixators and does not require the use of any software performing the calculation of the necessary adjustments. Moreover, said device enables the surgeon to reduce a dislocation within a single plane without modifying the adjustments made in the two other planes.
  • the devices of the prior art prevent or severely complicate the use of medical imaging.
  • medical imaging is required: at least two images (front-back and side planes) are needed.
  • fixators such as Ilizarov fixators or Taylor spatial frames
  • struts are positioned all around the bone and appear on the images, concealing or fading the bone image.
  • the medical imager automatically increases the radiation dose, thus fading the image of the bone segment and vainly irradiating the patient.
  • the orthopedic external fixator of the invention comprises sliding struts which may be positioned all around the bone while being movable from the field of view of the surgeon and of the medical imager, even after fixation of the pin or wires.
  • each strut may be moved by pure translation with one hand without displacing neither the pins nor the frame elements. Said feature also enables larger physical access to the bone.
  • the present invention relates to an orthopedic external fixation system comprising:
  • a posterior portion comprising a posterior rail having a mediolateral axis
  • a medial portion comprising a medial rail having an anteroposterior axis
  • a lateral portion comprising a lateral rail having an anteroposterior axis, the lateral and the medial rails being parallel;
  • each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis
  • each of the posterior, medial and lateral telescopic struts forms with respectively the rail of each of the posterior, medial and lateral portions of the first and second external fixation elements a joint allowing linear sliding movement of the posterior, medial and lateral telescopic struts along respectively the posterior, medial and lateral rails of the first and second external fixation elements.
  • the external fixation system comprises:
  • a posterior portion comprising a posterior plate and a posterior rail having a mediolateral axis
  • a medial portion comprising a medial plate extending from the posterior plate and a medial rail having an anteroposterior axis
  • a lateral portion comprising a lateral plate extending from the posterior plate and a lateral rail having an anteroposterior axis, the lateral and the medial rails being parallel;
  • a posterior telescopic strut having a first and a second end, the first end coupled to the posterior rail of the first external fixation element by a first strut-to-rail connector and the second end coupled to the posterior rail of the second external fixation element by a second strut-to-rail connector;
  • a medial telescopic strut having a first and a second end, the first end coupled to the medial rail of the first external fixation element by a first strut-to-rail connector and the second end coupled to the medial rail of the second external fixation element by a second strut-to-rail connector;
  • a lateral telescopic strut having a first and a second end, the first end coupled to the lateral rail of the first external fixation element by a first strut-to-rail connector and the second end coupled to the lateral rail of the second external fixation element by a second strut-to-rail connector;
  • each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis
  • each of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts forms with each corresponding rail a joint allowing linear sliding movement of each of the posterior, medial and lateral telescopic struts along respectively each of the posterior, medial and lateral rails of the first and second external fixation elements.
  • each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one rail-to-plate connector forming with the rail of respectively each of the posterior, medial and lateral portions of the first and second external fixation elements a revolute joint allowing rotation of each rail about its axis.
  • each of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts forms with each corresponding rail a prismatic joint allowing linear sliding movement of each of the posterior, medial and lateral telescopic struts along respectively each of the posterior, medial and lateral rails of the first and second external fixation elements.
  • each revolute and prismatic joint comprises means for locking the sliding of the prismatic joints and the rotation of the revolute joints and wherein the relative movement of the first and second external fixation elements is locked by locking at least three joints:
  • each of the posterior, medial and lateral portions of the first and second external fixation elements comprises two revolute joints allowing rotation of each rail about its axis; said two revolute joints comprising a rail and two rail-to-plate connectors coupling the ends of the rail of each of the posterior, medial and lateral portions of the first and second external fixation elements to respectively the plate of each of the posterior, medial and lateral portions of the first and second external fixation elements.
  • the rail of the posterior, medial and lateral portions of the first and second external fixation elements has a length along its axis higher than 50% of the length of respectively the plate of the posterior, medial and lateral portions of the first and second external fixation elements along the same axis.
  • the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts comprise a recess for receiving the rail of the posterior, medial and lateral portions of the first and second external fixation elements and wherein the length of each of said recess is less than 50% of the length of the rail along its axis; thereby enabling sliding of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts along at least 50% of the rail length of each of the posterior, medial and lateral rails of the first and second external fixation elements.
  • each of the posterior, medial and lateral telescopic struts are slidable along respectively each of the posterior, medial and lateral rails of the first and second external fixation elements independently of another of the posterior, medial and lateral telescopic struts.
  • the posterior telescopic strut further comprises a revolute joint allowing rotation of one of the strut-to-rail connectors about the anteroposterior axis.
  • at least one of the first and second external fixation elements is a rectangle.
  • the external fixation system further comprises at least a third external fixation element arranged at a distance to the first and the second external fixation elements, wherein the at least third external fixation elements is coupled to the first or the second external fixation element by a plurality of struts.
  • the first and second external fixation elements comprise a plurality of holes along the posterior, medial and lateral plates.
  • the external fixation system further comprises a plurality of fastening mechanisms adapted to be received in the plurality of holes and to link the first and second external fixation elements to respectively a first and a second bone segments.
  • the first and second external fixation elements comprise a slot along each of the posterior, medial and lateral plates.
  • the external fixation system according to the invention further comprises a plurality of fastening mechanisms adapted to slide in the slots and to link the first and second external fixation elements to respectively a first and a second bone segments.
  • Half pin refers to a bone fixation element which extends only on one side of the limb. Half pins are anchored to a single connector and in both cortices of the bone and create a unilateral external fixation.
  • Cylindrical joint refers to a joint having two degrees of freedom: a single-axis sliding function and a single-axis rotation function.
  • Bone refers to any bone fixation element known by one skilled in the art (e.g. tapered and/or self-drilling pins) and especially refers indifferently to half pin or trans-osseous wire.
  • Principal joint refers to a joint having one degree of freedom and a single-axis sliding function.
  • Cross-sectional shapes of a prismatic joint pin are selected to prevent rotation (e. g. polygonal cross-section), thereby permitting only translational movement.
  • Pure translation refers to a relative motion between two elements wherein the motion does not comprise any rotational movement (i.e. the relative orientation the two elements at the beginning and the end of the movement is maintained during the motion).
  • Revolute joint refers to a joint having one degree-of-freedom and a single-axis rotation function.
  • Trans-osseous wire refers to a transverse bone fixation element which extends completely out of each side of the limb. Trans-osseous wires are anchored to two connectors and provide a rigid construct leading to bilateral fixation. Tans-osseous wires may be thinner than half pins, as they are bilateral; thereby creating smaller defects in soft tissues. DETAILED DESCRIPTION
  • a three dimensional coordinate system is used to describe the position and orientations of the parts of the external fixation system.
  • the coordinate system includes a first direction, such as a superoinferior direction SI, a second direction, such as a mediolateral direction ML, and a third direction such as an anteroposterior direction AP, wherein each of the directions is perpendicular to both of the two other directions.
  • the present invention relates to an orthopedic external fixation system configured to be used for correcting bone injuries such as for instance dislocations.
  • the injured bone comprises a first segment such as a proximal segment and a second segment such as a distal segment.
  • the fixator is designed to be attached to the first segment and the second segment and to move at least one or both of the first and second bone segments relative to the other of the first and second bone segments thereby applying compressive or distractive loads on bone.
  • the bone fixator of the invention provides means for complete repositioning of the first and second bone segments relative to one another. Referring to FIG.
  • the fixator 1 comprises a plurality of external fixation elements (frames) 2 arranged at a distance to each other and a plurality of telescopic struts 3 configured to connect the plurality of external fixation elements 2.
  • the plurality of external fixation elements 2 is configured to be secured to respective bone segments.
  • the fixator 1 comprises at least two external fixation elements 2.
  • the fixator 1 comprises a pair of external fixation elements 2 such as a first or proximal external fixation element and a second or distal external fixation element.
  • the proximal external fixation element and the distal external fixation element are configured to be attached to the first and second bone segment respectively.
  • the fixator 1 may comprise additional external fixation elements 2.
  • the external fixation elements 2 are identical. In one embodiment, the external fixation elements 2 are not identical and may vary in shape and size. In one embodiment, the external fixation element 2 is planar. In one embodiment, the external fixation element 2 is a monolithic piece of material or may be made of separate pieces of material that are joined together. In one embodiment, the thickness is constant throughout the external fixation element 2. In another embodiment, the thickness is not constant throughout the external fixation element 2.
  • the external fixation elements 2 comprise a posterior portion and two parallel portions (lateral and medial) extending from the posterior portion. In one embodiment, the two lateral and medial parallel portions extend from the posterior portion in the same direction. In one embodiment, the external fixation elements 2 also comprise an anterior portion and form a rectangle or square. In one embodiment, the posterior, medial and lateral portions, and optionally the anterior portion, are longitudinal. As depicted in FIGS. 2 and 3, the external fixation element is U-shaped. In one embodiment, the external fixation elements 2 have the same shape. In one embodiment, the external fixation elements 2 have different shapes, as disclosed in FIG. 20.
  • the inner periphery of the external fixation elements 2 has any shape suitable for one skilled in the art such as a square, a rectangle, a ring, an hexagon or a portion thereof.
  • the inner periphery of the external fixation elements 2 may be a ring and the posterior, medial and lateral portions are tangential to the said ring.
  • closed external fixation elements such as rings or squares
  • opened external fixation elements such as U-shaped elements, enable positioning of a ready-to-use fixator around a limb, such as an ankle or a foot.
  • the external fixation system may be defined as ready-to-use (i.e. already assembled) around a limb such as an ankle or foot.
  • external fixation elements 2 are configured to be located around a limb such that the posterior portion is positioned posterior, or behind, the limb and the gap is dimensioned and positioned to receive the limb.
  • each portion comprises a plate 21 and a rail 22 having a longitudinal axis.
  • the rail 22 is positioned on one side, preferably the outer side, of the plate 21.
  • the posterior portion comprises a posterior plate 21a and a posterior rail 22a having a mediolateral axis.
  • the medial portion comprises a medial plate 21b extending from the posterior plate 21a and a medial rail 22b having an anteroposterior axis.
  • the lateral portion comprises a lateral plate 21c extending from the posterior plate 21a and a lateral rail 22c having an anteroposterior axis.
  • each rail 22 has a length along its axis longer than 50% of the length of the corresponding plate 21 along the same axis, preferably longer than 60%, 70%, 80% or 90% of the length of the corresponding plate 21 along the same axis.
  • each plate 21 serves as bearing elements for pins which are in connection with bone segments.
  • the plates 21a, 21b, 21c of the external fixation system 1 comprise a plurality of holes 23.
  • the plurality of holes 23 extends through the plates 21a, 21b, 21c; for example the holes 23 extend through an entirety of the thickness of the plates 21a, 21b, 21c.
  • the plurality of holes 23 extends along the whole length plates 21a, 21b, 21c.
  • the plurality of holes 23 are centrally designed with regard to the width of plates 21a, 21b, 21c.
  • the holes 23 are configured to receive fastening mechanisms for connecting pins.
  • the holes 23 are not configured to receive the struts 3.
  • the plates 21a, 21b, 21c of the external fixation system 1 further comprise a second set of holes shifted with respect to the first set thereby increasing the positioning possibilities.
  • each plate 21 of the external fixation system 1 comprises a longitudinal slot 24.
  • the posterior plate 21a comprises a posterior slot 24a.
  • the medial plate 21b comprises a medial slot 24b.
  • the lateral plate 21c comprises a lateral slot 24c.
  • each slot 24 has a length along its longitudinal axis bigger than 50% of the length of the corresponding plate 21 along the same axis.
  • each slot 24 has a length along its longitudinal axis longer than 60%, 70%, 80% or 90% of the length of the corresponding plate 21 along the same axis.
  • each slot 24 is configured to receive fastening mechanisms to connect pins.
  • the fastening mechanisms are received in a sliding manner in the slot 24; thereby enabling easy positioning of the fastening mechanisms along the slot 24.
  • the slots 24 are not configured to receive the struts 3.
  • at least one plate 21 may comprise a plurality of holes 23 and at least another plate 21 may comprise a longitudinal slot 24.
  • the external fixation system 1 comprises at least two telescopic struts 3.
  • the fixator 1 comprises at least three telescopic struts 3: a posterior telescopic strut 3a, a medial telescopic strut 3b and a lateral telescopic strut 3c.
  • the fixator 1 comprises only three telescopic struts 3: a posterior telescopic strut 3a, a medial telescopic strut 3b and a lateral telescopic strut 3c.
  • the telescopic struts 3 attach adjacent ones of the plurality of external fixation elements 2.
  • the telescopic struts 3 are not crossed with each other. In one embodiment, the telescopic struts 3 are adjustable in length. In one embodiment, the telescopic struts 3 comprise a length adjusting mechanism. In one embodiment, the length adjusting mechanism may be any mechanism known by one skilled in the art such as for instance a threaded rod and a corresponding sleeve or a recess and a corresponding rail or ball slide guides. In one embodiment, the telescopic struts 3 comprise an actuator for locking the length of said strut 3. Referring to FIGS. 5 to 8, each telescopic strut 3 comprises a first end 31 and a second end 32.
  • each first end 31 is coupled to a corresponding rail 22 of a first external fixation element 2 by a first strut-to-rail connector and each second end 32 is coupled to a corresponding rail 22 of the second external fixation element 2 by a second strut-to-rail connector.
  • each strut-to-rail connector forms with a corresponding rail a joint allowing at least a linear sliding movement of the strut along the rail.
  • each strut-to-rail connector forms with a corresponding rail a prismatic joint allowing linear sliding movement of the strut along the rail.
  • the prismatic joint may be any mechanism known by one skilled in the art such as for instance a threaded rod and a corresponding sleeve or a recess and a corresponding rail or ball slide guides.
  • the strut-to-rail connector does not form with the corresponding rail a screw joint.
  • the rail is not a threaded rod.
  • the rail is a longitudinal structure having a smooth polygonal cross-section.
  • each strut-to-rail connector forms with the corresponding rail a prismatic joint with a polygonal cross-section allowing linear sliding movement of a strut relative to a corresponding rail. Said embodiment enables free translation of the struts relative to the rail; while threaded rods enable only controlled minimal translation.
  • the first and the second strut-to-rail connectors of each strut 3 comprise a longitudinal recess 33 designed to receive a rail 22 in a sliding manner.
  • the rail 22 or the recess 33 respectively would have a corresponding nesting cross-sectional shape.
  • the recess 33 and the rail 22 form a prismatic joint allowing linear sliding movement of the strut 3 relative to the rail 22 and thus linear sliding movement of each strut 3 along its corresponding rail 22 of the first and second external fixation elements (i.e.
  • each strut 3 may slide along the corresponding rails 22 of the first and second external fixation elements 2 without relative movement between the first and second external fixation elements 2.
  • the strut-to-rail connector comprises a hole 34 which extends through the thickness of the connector up to the recess 33.
  • each strut 3 is slidable along the corresponding rails of the first and second external fixation elements independently of the other struts 3.
  • each strut-to-rail connector comprises a recess 33 having a longitudinal axis for receiving the rail 22 and the length of said recess 33 along its axis is ranging from 5% to 50% of the length of the rail 22 along its axis; thereby enabling sliding of each strut-to-rail connector along at least 50% of the length of the rail 22.
  • each strut-to-rail connector comprises a recess 33 having a longitudinal axis for receiving the rail 22 and the length of said recess 33 along its axis is ranging from 5% to 40%, 5% to 30%, 5% to 20% or 5% to 10% of the length of the rail 22 along its axis.
  • each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis.
  • each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one revolute joint allowing rotation of each rail about its axis.
  • the rails 22 have cross-sections preventing rotation, such as polygonal cross-sections.
  • the rails further comprise two cylindrical ends.
  • each rail 22 comprises a main portion 221 with a polygonal cross section and two ends 222 with a circular cross-section.
  • the length of each ends 222 ranges from 0.1% to 10%, preferably from 1 to 5%, of the length of the main portion 221.
  • each rail 22 is coupled to the corresponding plate 21 by at least one rail-to-plate connector 5.
  • FIG. 1 as depicted in FIG.
  • each rail 22 is coupled to the corresponding plate 21 by two rail-to-plate connectors 5, on each end of the rail 21.
  • each rail 22 has a length along its axis between the two rail-to-plate connectors higher than 50% of the length of the corresponding plate 21 along the same axis, preferably higher than 60%, 70%, 80% or 90% of the length of the corresponding plate 21 along the same axis.
  • the rail-to-plate connector 5 comprises a first end 51 adapted to be coupled to a plate 21.
  • the first end 51 comprises a hole 511 cooperating with a hole of the plate 21, thereby ensuring connection between the plate 21 and the rail-to-plate connector 5 by means of a screw.
  • the rail-to-plate connector 5 comprises a second end 52 adapted to be coupled to a rail 22.
  • the second end 52 comprises a circular recess 521 cooperating with the end 222 of the rail 22; thereby forming a plain bearing allowing rotation of the rail about its axis.
  • the at least one revolute joint allowing rotation of each rail about its axis is a ball bearing.
  • each rail 22 is connected to the corresponding plate 21 by means of two rail-to-plate connectors 5, each comprising a first end 51 coupled to the plate 21 and a second end 52 comprising a circular recess 521 cooperating with each end 222 of the rail 22.
  • only one of the revolute joint of the two revolute joints formed at each end of each rail comprises a locking mechanism to lock the rotation of the rail.
  • one of the cylindrical ends of the rails 22 extends out of the circular recess 521 and comprises a thread such that said revolute joint may be locked with a nut 25 by screwing down.
  • the first and the second strut-to-rail-connectors of each strut are integral with said strut.
  • at least one of the strut-to-rail connector of at least one of the strut is not integral with said strut.
  • at least one of the struts 3 is connected to one of the strut-to- rail connector by a connecting mechanism comprising a revolute joint allowing rotation of said strut-to-rail connector with respect to the strut about the anterioposterior axis.
  • at least one strut 3 (e.g.
  • the posterior strut 3a) further comprises a revolute joint allowing rotation of one of the strut-to-rail connector about the anteroposterior axis.
  • a single strut 3 of the external fixation system comprises a revolute joint allowing rotation of one of the first or the second strut-to-rail connector about the anteroposterior axis. Said embodiment enables the rotation about the anteroposterior axis of one of the external fixation element 2 while the second external fixation element 2 maintains its orientation.
  • said revolute joint may be any revolute joint known by one skilled in the art such as plain bearings or ball bearings.
  • said revolute joint is formed by a pin extending from the strut-to-rail connector through a corresponding hole 36 of the strut.
  • said pin further extends out of the struts, on the opposite side, with a thread such that said revolute joint may be locked with a nut by screwing down.
  • the strut-to-rail connectors comprise a cylindrical recess and the rails are cylindrical such that each strut-to-rail connector forms with the corresponding rail a cylindrical joint.
  • the rail-to-plate connectors 5 of the posterior, medial and lateral portions do not comprise revolute joints.
  • At least one rail 22 further comprises two sliding carriages 29, one on each side of the telescopic strut 3. Said sliding carriages 29 slide relative to the rail and the distance between said two sliding carriages 29 is defined and fixed by the two ends of a worm screw 28.
  • the worm screw 28 passes through a threaded hole of the struts 3.
  • Said sliding carriage 29 may be fixed relative to the rail 22 with at least one locking mechanism.
  • the sliding carriages 29 are fixed relative to the rail 22 and the worm screw 28 is screwed such as to refine the positon of the strut 3 with respect to the sliding carriage in a fine and incremental manner.
  • the external fixator is configured such that the first external element is moveable relative to the second external fixation element in at least 3 degrees of freedom, especially, the first external element can at least translate relative to the second external element independently in the anteroposterior direction, in the mediolateral direction and in the superoinferior direction.
  • Said technical feature enable the reduction of dislocation within each direction separately. With devices of the prior art wherein the movement in the three directions are not independent, reduction of the dislocation within one direction may increase the dislocation within another direction.
  • the first external fixation element may rotate relative to the second external fixation element about the anteroposterior direction. In one embodiment, the first external fixation element cannot rotate relative to the second external fixation element about the superoinferior direction. In one embodiment, the first external fixation element cannot rotate about the mediolateral direction relatively to the second external fixation element.
  • each joint of the external fixation system comprises a single degree of freedom.
  • each joint of the external fixation system comprises a locking mechanism for locking its single degree of freedom.
  • said locking mechanism may be a nut.
  • said locking mechanism may be a cam lever, preferably a cam lever with a removable lever; such as to prevent unintentional untighten.
  • the relative movement of the first and second external fixation elements may be fully locked (i.e. in translation and rotation) by locking only three joints namely:
  • the external fixation system further comprises a plurality of fastening mechanisms 4 that are configured to attach a bone segment to an external fixation element 2, especially to attach a first bone segment to a first external fixation element and a second bone segment to a second external fixation element such that as the first and second external fixation elements move relatively to one another, the first and second bone segments also move relatively to one another.
  • the fastening mechanisms 4 are configured such that the external fixation element 2 and the bone segment are translationally and rotationally coupled.
  • the fastening mechanism 4 comprises a bracket that can be attached to the external fixation element 2 by any means known by one skilled in the art such as for instance a fastener, an axis locked by a stop pin, a pressure screw, a nut, a quick lock system or a clamp collar.
  • the fastening mechanism 4 further comprises a bone fixation element that couples the bracket to the bone such as pins.
  • the bone fixation element is attached to the bracket by any means known by one skilled in the art such as for example a fastener, a pressure screw, a quick lock system or an adhesive material.
  • the fastening mechanism 4 may be coupled to holes 23 of a plate 21 or may be mounted in a sliding manner within a slot 24 of a plate 21. In the latter embodiment, the fastening mechanism 4 may be translated along the plate 21 to be positioned easily at the right place by the surgeon. According to one embodiment, the fastening mechanism 4 may be rotated with respect to the plate 21. According to one embodiment, if the pin will not be positioned within the plane of the external fixation system, the fastening mechanism 4 further comprises a revolute joint (see FIG. 14). According to one embodiment, the fastening mechanism 4 comprises at least one tab extending within the plate 21 preventing rotation of the fastening mechanism 4 with respect to said plate 21.
  • the external fixation system further comprises at least a third external fixation element 2 arranged at a distance to the first and the second external fixation elements 2, wherein the at least third external fixation element is coupled to the first or the second external fixation elements by a plurality of struts.
  • the third external fixation element is identical to one of the first or second external fixation elements.
  • the third external fixation element is different to the first and second external fixation elements.
  • the third external fixation element comprises at least one fixation point suitable for receiving one pin. Said embodiment may be useful for maximum stability as one pin may be as close to the fracture as possible and one other pin may be as far from the fracture as possible.
  • the external fixation system especially the external fixation elements and/or the telescopic struts, can be manufactured in various sizes and length, depending for instance on adult or pediatric use.
  • At least one of the external fixation element 2 comprises a longitudinal plate connected by a revolute joint to a U- shaped external fixation element; said revolute joint enabling rotation within the plane of the U-shaped external fixation element.
  • the external fixation system 2 comprises a revolute joint between the anterior plate and the medial plate 21b.
  • the lateral end of the anterior plate further comprises at least one hole 26 through which at least one pin 27, sliding within the anterior end of the lateral plane 21c, may be inserted; thereby locking the rotation.
  • the external fixation system are made of a radiolucent material such as a polymer, for instance poly ether ether ketone (PEEK).
  • PEEK poly ether ether ketone
  • the material of the external fixation system is selected from a polymer, a plastic, a reinforced plastic, a plastic-carbon composite or a fiber resin composite.
  • the material of the external fixation system is selected from steel alloy, aluminum alloy, titanium alloy or magnesium alloy.
  • the external fixation system is applied to the tibia, the fibula, the foot, the calcaneus, the talus, the Chopart joint, the Lisfranc joint, the ankle, the femur, the humerus, the radius, the ulna, the hand or the forearm.
  • a treatment plan can be performed to move the first and second external fixation elements into a second orientation. In the second orientation, the first and second bone segments are in a desired position.
  • the present invention also relates to a method of reducing dislocation comprising the following steps:
  • the present invention relates to a method of reducing ankle dislocation of a subject comprising the following steps:
  • the dislocation is located at the lower part of the tibia, fibula, talus and calcaneus.
  • Figure 1 is a perspective view of an external fixation system 1 according to one embodiment of the invention.
  • Figure 2 is a perspective view of the posterior, medial and lateral plates 21a, 21b, 21c of an external fixation element 2 according to one embodiment of the invention.
  • Figure 3 is a perspective view of the posterior, medial and lateral plates 21a, 21b, 21c of an external fixation element 2 according to another embodiment of the invention.
  • Figure 4 is a top view of an external fixation system 1 according to one embodiment of the invention.
  • Figure 5 is a perspective view of a telescopic strut 3 according to one embodiment of the invention.
  • Figure 6 is a perspective view of a telescopic strut 3 according to one embodiment of the invention.
  • Figure 7 is a perspective view of the telescopic strut 3 of figure 6.
  • Figure 8 is a front view of the telescopic strut 3 of figure 6.
  • Figure 9 is a perspective view illustrating a rail 22 according to one embodiment of the invention.
  • Figure 10 is a perspective view of a rail-to-plate connector 5 according to one embodiment of the invention.
  • Figure 11 is a perspective view of a strut 3 and a corresponding rail 22 according to one embodiment of the invention.
  • Figure 12 illustrates a side view of the external fixation system 1 according to one embodiment of the invention.
  • Figure 13 is a front view of an external fixation system 1 according to one embodiment of the invention.
  • Figure 14 illustrates a fastening mechanism 4 according to one embodiment of the invention.
  • Figure 15 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention.
  • Figure 16 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention, in use wherein a subject has a dislocated ankle.
  • Figure 17 illustrates a front view of an external fixation system 1 according to one embodiment of the invention, in use wherein a subject has a dislocated ankle.
  • Figure 18 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention, in use wherein the ankle dislocation has been reduced.
  • Figure 19 illustrates a front view of an external fixation system 1 according to one embodiment of the invention, in use wherein the ankle dislocation has been reduced.
  • Figure 20 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention.
  • Figure 21 is a perspective view of the posterior, medial and lateral plates 21a, 21b, 21c of an external fixation element 2 according to one embodiment of the invention.

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Abstract

The present invention relates to an orthopedic external fixation system comprising at least a first and a second external fixation element (2) arranged at a distance to each other, each comprising at least a posterior portion, a medial portion and a lateral portion; a posterior telescopic strut (3a), a medial telescopic strut (3b) and a lateral telescopic strut (3c); each strut being coupled to the first and the second external fixation element (2).

Description

EXTERNAL FIXATION SYSTEM
FIELD OF INVENTION
The present invention pertains to the field of orthopedics. Especially, this invention relates to an external fixation system, more specifically to an external orthopedic fixation system for intuitive and independent relative translational motions between the frame elements in three directions.
BACKGROUND OF INVENTION Orthopedic external fixation systems are used for stabilization and immobilization of dislocations or joint fractures. External fixators can be used as a primary means of reduction of dislocations and joint fractures or may be used in procedures involving temporary external fixation to stabilize the injury and allow soft tissues to recover and secondary surgical procedure of definitive internal fixation. External fixation systems typically comprise a series of pins or wires, suitable for insertion within bone, externally connected to a rigid frame enabling correction of the alignment of bone segments.
Nowadays, external fixators include planar and multi-planar fixators, Ilizarov devices, Taylor spatial frames and similar systems.
Planar fixators comprise at least one rod attached with pins above and below a fracture site through one (unilateral) or both (bilateral) side of the bone. Planar frames do not allow multi-planar manipulation after the frame (the rod) is applied. Multi-planar device improves the stability of the device but not as efficiently as Ilizarov devices.
Ilizarov devices or similar circular external fixators, such as those disclosed in US 4,890,631 or US 2014/0058389, comprise at least two external rings or partial rings externally connected by threaded rods. The frames, which encircle the limb, are attached to the bone by crossing trans-osseous wires or half pins. Said device are adapted for use in the method known as the Ilizarov method. On the contrary to planar fixators, Ilizarov or similar devices allows fixation of wires or pins all around the bone. However, said devices allows mainly relative superoinferior motions between the at least two rings. In the device disclosed in US 2014/0058389, translation of the central axis of one of the ring towards or away the central axis of each threaded rods can also be achieved. However, said devices do not allow pure translational motions between the frame elements.
The Taylor spatial frame or similar fixators, such as those disclosed in US 5,702,389, US 2013/0245625 or US 2014/0276821, comprises two rings connected with six crossed telescopic rods or struts that can be independently lengthened or shortened relative to the rest of the frame. Said devices allow a full six axes of movement. The adjustment of the six independent rods requires a computer application which provides day-by-day treatment plan. Said devices do not allow pure relative translation of the rings and require unlocking of the six rods in order to adjust the relative position of the rings.
Another external fixation system of the prior art, WO 2014/163591, discloses a fixation system comprising two rings connected by telescopic struts wherein one of the two rings comprises four tangential sled systems enabling movement of the struts by means of threaded rods. WO 2010/104567 discloses an external fixation system comprising first and second planar circular ring elements, each comprising a ring gear, and telescopic struts; wherein the two ends of each strut are not configured to slide along the ring gear of the planar circular ring elements.
GB 2101488 describes a fixation system comprising at least two calipers comprising pin holders and at least two distractions bars joining the calipers together; wherein the pin holders are located at the ends of the distractions bars; thereby preventing movement of the distractions bars once pins, penetrating into bone tissue, are secured to the pin holders. None of the existing device allows intuitive and independent pure relative translations between the frame elements. Existing devices require complex combination of rotations and translations, eventually assisted by software. The vision in space and the combination of rotations to achieve a desired movement is barely intuitive, even for the most experienced surgeons.
The present orthopedic external fixator aims at providing an easy-to-use fixator, implementing simple motion compared to the devices of the prior art. Especially, every joint of the external fixator comprises less than 3 degrees of freedom, for instance a single or 2 degrees of freedom, so that the user may precisely know which motion will be implemented. The present orthopedic external fixator includes means for carrying out at least pure relative translations between the frame elements, independently in three directions. The present invention can be used by surgeons with basic training in orthopedic fixators and does not require the use of any software performing the calculation of the necessary adjustments. Moreover, said device enables the surgeon to reduce a dislocation within a single plane without modifying the adjustments made in the two other planes.
Furthermore, the devices of the prior art prevent or severely complicate the use of medical imaging. Indeed, in order to fix the pins or wires to the bone, medical imaging is required: at least two images (front-back and side planes) are needed. However, in fixators such as Ilizarov fixators or Taylor spatial frames, struts are positioned all around the bone and appear on the images, concealing or fading the bone image. For instance with current medical imagers, if a metallic strut is located within its field of view, the medical imager automatically increases the radiation dose, thus fading the image of the bone segment and vainly irradiating the patient. In order to overcome said drawback, the orthopedic external fixator of the invention comprises sliding struts which may be positioned all around the bone while being movable from the field of view of the surgeon and of the medical imager, even after fixation of the pin or wires. In particular, each strut may be moved by pure translation with one hand without displacing neither the pins nor the frame elements. Said feature also enables larger physical access to the bone. SUMMARY
The present invention relates to an orthopedic external fixation system comprising:
- at least a first and a second external fixation elements arranged at a distance to each other, each comprising at least
- a posterior portion comprising a posterior rail having a mediolateral axis;
- a medial portion comprising a medial rail having an anteroposterior axis;
- a lateral portion comprising a lateral rail having an anteroposterior axis, the lateral and the medial rails being parallel;
- a posterior telescopic strut coupled to the posterior rail of the first and second external fixation;
- a medial telescopic strut coupled to the medial rail of the first and second external fixation elements;
- a lateral telescopic strut coupled to the lateral rail of the first and second external fixation element;
wherein each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis; and
wherein each of the posterior, medial and lateral telescopic struts forms with respectively the rail of each of the posterior, medial and lateral portions of the first and second external fixation elements a joint allowing linear sliding movement of the posterior, medial and lateral telescopic struts along respectively the posterior, medial and lateral rails of the first and second external fixation elements.
According to one embodiment, the external fixation system comprises:
- at least a first and a second external fixation element arranged at a distance to each other, each comprising at least
- a posterior portion comprising a posterior plate and a posterior rail having a mediolateral axis;
- a medial portion comprising a medial plate extending from the posterior plate and a medial rail having an anteroposterior axis; - a lateral portion comprising a lateral plate extending from the posterior plate and a lateral rail having an anteroposterior axis, the lateral and the medial rails being parallel;
- a posterior telescopic strut having a first and a second end, the first end coupled to the posterior rail of the first external fixation element by a first strut-to-rail connector and the second end coupled to the posterior rail of the second external fixation element by a second strut-to-rail connector;
- a medial telescopic strut having a first and a second end, the first end coupled to the medial rail of the first external fixation element by a first strut-to-rail connector and the second end coupled to the medial rail of the second external fixation element by a second strut-to-rail connector;
- a lateral telescopic strut having a first and a second end, the first end coupled to the lateral rail of the first external fixation element by a first strut-to-rail connector and the second end coupled to the lateral rail of the second external fixation element by a second strut-to-rail connector;
wherein each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis; and
wherein each of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts forms with each corresponding rail a joint allowing linear sliding movement of each of the posterior, medial and lateral telescopic struts along respectively each of the posterior, medial and lateral rails of the first and second external fixation elements.
According to one embodiment, each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one rail-to-plate connector forming with the rail of respectively each of the posterior, medial and lateral portions of the first and second external fixation elements a revolute joint allowing rotation of each rail about its axis.
According to one embodiment, each of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts forms with each corresponding rail a prismatic joint allowing linear sliding movement of each of the posterior, medial and lateral telescopic struts along respectively each of the posterior, medial and lateral rails of the first and second external fixation elements.
According to one embodiment, each revolute and prismatic joint comprises means for locking the sliding of the prismatic joints and the rotation of the revolute joints and wherein the relative movement of the first and second external fixation elements is locked by locking at least three joints:
- one revolute joint between one of the posterior rails and the corresponding rail-to-plate connector;
- one revolute joint between one of the lateral or medial rails and the corresponding rail-to-plate connector; and
- the translation of one of the medial or lateral telescopic strut.
According to one embodiment, each of the posterior, medial and lateral portions of the first and second external fixation elements comprises two revolute joints allowing rotation of each rail about its axis; said two revolute joints comprising a rail and two rail-to-plate connectors coupling the ends of the rail of each of the posterior, medial and lateral portions of the first and second external fixation elements to respectively the plate of each of the posterior, medial and lateral portions of the first and second external fixation elements.
According to one embodiment, the rail of the posterior, medial and lateral portions of the first and second external fixation elements has a length along its axis higher than 50% of the length of respectively the plate of the posterior, medial and lateral portions of the first and second external fixation elements along the same axis.
According to one embodiment, the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts comprise a recess for receiving the rail of the posterior, medial and lateral portions of the first and second external fixation elements and wherein the length of each of said recess is less than 50% of the length of the rail along its axis; thereby enabling sliding of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts along at least 50% of the rail length of each of the posterior, medial and lateral rails of the first and second external fixation elements.
According to one embodiment, each of the posterior, medial and lateral telescopic struts are slidable along respectively each of the posterior, medial and lateral rails of the first and second external fixation elements independently of another of the posterior, medial and lateral telescopic struts.
According to one embodiment, the posterior telescopic strut further comprises a revolute joint allowing rotation of one of the strut-to-rail connectors about the anteroposterior axis. According to one embodiment, at least one of the first and second external fixation elements is a rectangle.
According to one embodiment, the external fixation system according to the invention further comprises at least a third external fixation element arranged at a distance to the first and the second external fixation elements, wherein the at least third external fixation elements is coupled to the first or the second external fixation element by a plurality of struts.
According to one embodiment, the first and second external fixation elements comprise a plurality of holes along the posterior, medial and lateral plates.
According to one embodiment, the external fixation system according to the invention further comprises a plurality of fastening mechanisms adapted to be received in the plurality of holes and to link the first and second external fixation elements to respectively a first and a second bone segments.
According to one embodiment, the first and second external fixation elements comprise a slot along each of the posterior, medial and lateral plates. According to one embodiment, the external fixation system according to the invention further comprises a plurality of fastening mechanisms adapted to slide in the slots and to link the first and second external fixation elements to respectively a first and a second bone segments.
DEFINITIONS In the present invention, the following terms have the following meanings:
"Half pin" refers to a bone fixation element which extends only on one side of the limb. Half pins are anchored to a single connector and in both cortices of the bone and create a unilateral external fixation.
"Cylindrical joint" refers to a joint having two degrees of freedom: a single-axis sliding function and a single-axis rotation function.
"Pin" refers to any bone fixation element known by one skilled in the art (e.g. tapered and/or self-drilling pins) and especially refers indifferently to half pin or trans-osseous wire.
"Prismatic joint" refers to a joint having one degree of freedom and a single-axis sliding function. Cross-sectional shapes of a prismatic joint pin are selected to prevent rotation (e. g. polygonal cross-section), thereby permitting only translational movement.
"Pure translation" refers to a relative motion between two elements wherein the motion does not comprise any rotational movement (i.e. the relative orientation the two elements at the beginning and the end of the movement is maintained during the motion).
"Revolute joint" refers to a joint having one degree-of-freedom and a single-axis rotation function.
"Trans-osseous wire" refers to a transverse bone fixation element which extends completely out of each side of the limb. Trans-osseous wires are anchored to two connectors and provide a rigid construct leading to bilateral fixation. Tans-osseous wires may be thinner than half pins, as they are bilateral; thereby creating smaller defects in soft tissues. DETAILED DESCRIPTION
The following detailed description will be better understood when read in conjunction with the drawings. For the purpose of illustrating, the device is shown in the preferred embodiments. It should be understood, however that the application is not limited to the precise arrangements, structures, features, embodiments, and appearance shown. The drawings are not drawn to scale and are not intended to limit the scope of the claims to the embodiments depicted. Certain terminologies are used in the following detailed description only for convenience and are not limiting. The words "anterior", "posterior", "superior", "inferior", "medial" and related words and sentences design positions and orientations as used in medical terminology.
A three dimensional coordinate system is used to describe the position and orientations of the parts of the external fixation system. The coordinate system includes a first direction, such as a superoinferior direction SI, a second direction, such as a mediolateral direction ML, and a third direction such as an anteroposterior direction AP, wherein each of the directions is perpendicular to both of the two other directions.
The present invention relates to an orthopedic external fixation system configured to be used for correcting bone injuries such as for instance dislocations. In one embodiment, the injured bone comprises a first segment such as a proximal segment and a second segment such as a distal segment. The fixator is designed to be attached to the first segment and the second segment and to move at least one or both of the first and second bone segments relative to the other of the first and second bone segments thereby applying compressive or distractive loads on bone. Thus, the bone fixator of the invention provides means for complete repositioning of the first and second bone segments relative to one another. Referring to FIG. 1, the fixator 1 comprises a plurality of external fixation elements (frames) 2 arranged at a distance to each other and a plurality of telescopic struts 3 configured to connect the plurality of external fixation elements 2. In one embodiment, the plurality of external fixation elements 2 is configured to be secured to respective bone segments. The fixator 1 comprises at least two external fixation elements 2. In one embodiment, the fixator 1 comprises a pair of external fixation elements 2 such as a first or proximal external fixation element and a second or distal external fixation element. In one embodiment, the proximal external fixation element and the distal external fixation element are configured to be attached to the first and second bone segment respectively. The fixator 1 may comprise additional external fixation elements 2. In one embodiment, the external fixation elements 2 are identical. In one embodiment, the external fixation elements 2 are not identical and may vary in shape and size. In one embodiment, the external fixation element 2 is planar. In one embodiment, the external fixation element 2 is a monolithic piece of material or may be made of separate pieces of material that are joined together. In one embodiment, the thickness is constant throughout the external fixation element 2. In another embodiment, the thickness is not constant throughout the external fixation element 2.
In one embodiment, the external fixation elements 2 comprise a posterior portion and two parallel portions (lateral and medial) extending from the posterior portion. In one embodiment, the two lateral and medial parallel portions extend from the posterior portion in the same direction. In one embodiment, the external fixation elements 2 also comprise an anterior portion and form a rectangle or square. In one embodiment, the posterior, medial and lateral portions, and optionally the anterior portion, are longitudinal. As depicted in FIGS. 2 and 3, the external fixation element is U-shaped. In one embodiment, the external fixation elements 2 have the same shape. In one embodiment, the external fixation elements 2 have different shapes, as disclosed in FIG. 20. In an embodiment, the inner periphery of the external fixation elements 2 has any shape suitable for one skilled in the art such as a square, a rectangle, a ring, an hexagon or a portion thereof. For instance, the inner periphery of the external fixation elements 2 may be a ring and the posterior, medial and lateral portions are tangential to the said ring. On the contrary to closed external fixation elements, such as rings or squares, opened external fixation elements, such as U-shaped elements, enable positioning of a ready-to-use fixator around a limb, such as an ankle or a foot. In one embodiment, when at least one of the at least two external fixation elements is U- shaped, the external fixation system may be defined as ready-to-use (i.e. already assembled) around a limb such as an ankle or foot.
The inner periphery of the external fixation element 2 defines a gap. In an embodiment, external fixation elements 2 are configured to be located around a limb such that the posterior portion is positioned posterior, or behind, the limb and the gap is dimensioned and positioned to receive the limb.
In one embodiment, as depicted in FIG. 4, each portion comprises a plate 21 and a rail 22 having a longitudinal axis. In one embodiment, the rail 22 is positioned on one side, preferably the outer side, of the plate 21. In one embodiment, the posterior portion comprises a posterior plate 21a and a posterior rail 22a having a mediolateral axis. In one embodiment, the medial portion comprises a medial plate 21b extending from the posterior plate 21a and a medial rail 22b having an anteroposterior axis. In one embodiment, the lateral portion comprises a lateral plate 21c extending from the posterior plate 21a and a lateral rail 22c having an anteroposterior axis. In one embodiment, the lateral and the medial rails 22b, 22c are substantially parallel. In one embodiment, the posterior, medial and lateral rails, and optionally the anterior rail, are longitudinal. According to one embodiment, each rail 22 has a length along its axis longer than 50% of the length of the corresponding plate 21 along the same axis, preferably longer than 60%, 70%, 80% or 90% of the length of the corresponding plate 21 along the same axis.
In one embodiment, each plate 21 serves as bearing elements for pins which are in connection with bone segments.
In one embodiment, as depicted in FIG. 2, the plates 21a, 21b, 21c of the external fixation system 1 comprise a plurality of holes 23. In one embodiment, the plurality of holes 23 extends through the plates 21a, 21b, 21c; for example the holes 23 extend through an entirety of the thickness of the plates 21a, 21b, 21c. In one embodiment, the plurality of holes 23 extends along the whole length plates 21a, 21b, 21c. In one embodiment, the plurality of holes 23 are centrally designed with regard to the width of plates 21a, 21b, 21c. In one embodiment, the holes 23 are configured to receive fastening mechanisms for connecting pins. In one embodiment, the holes 23 are not configured to receive the struts 3. According to another embodiment, the plates 21a, 21b, 21c of the external fixation system 1 further comprise a second set of holes shifted with respect to the first set thereby increasing the positioning possibilities.
In another embodiment, as depicted in FIG. 3, each plate 21 of the external fixation system 1 comprises a longitudinal slot 24. In one embodiment, the posterior plate 21a comprises a posterior slot 24a. In one embodiment, the medial plate 21b comprises a medial slot 24b. In one embodiment, the lateral plate 21c comprises a lateral slot 24c. In one embodiment, each slot 24 has a length along its longitudinal axis bigger than 50% of the length of the corresponding plate 21 along the same axis. In one embodiment, each slot 24 has a length along its longitudinal axis longer than 60%, 70%, 80% or 90% of the length of the corresponding plate 21 along the same axis. In one embodiment, each slot 24 is configured to receive fastening mechanisms to connect pins. In one embodiment, the fastening mechanisms are received in a sliding manner in the slot 24; thereby enabling easy positioning of the fastening mechanisms along the slot 24. In one embodiment, the slots 24 are not configured to receive the struts 3. In one embodiment, at least one plate 21 may comprise a plurality of holes 23 and at least another plate 21 may comprise a longitudinal slot 24.
In one embodiment, the external fixation system 1 comprises at least two telescopic struts 3. In one embodiment, the fixator 1 comprises at least three telescopic struts 3: a posterior telescopic strut 3a, a medial telescopic strut 3b and a lateral telescopic strut 3c. In one embodiment, the fixator 1 comprises only three telescopic struts 3: a posterior telescopic strut 3a, a medial telescopic strut 3b and a lateral telescopic strut 3c. In one embodiment, the telescopic struts 3 attach adjacent ones of the plurality of external fixation elements 2. In one embodiment, the telescopic struts 3 are not crossed with each other. In one embodiment, the telescopic struts 3 are adjustable in length. In one embodiment, the telescopic struts 3 comprise a length adjusting mechanism. In one embodiment, the length adjusting mechanism may be any mechanism known by one skilled in the art such as for instance a threaded rod and a corresponding sleeve or a recess and a corresponding rail or ball slide guides. In one embodiment, the telescopic struts 3 comprise an actuator for locking the length of said strut 3. Referring to FIGS. 5 to 8, each telescopic strut 3 comprises a first end 31 and a second end 32. In one embodiment, each first end 31 is coupled to a corresponding rail 22 of a first external fixation element 2 by a first strut-to-rail connector and each second end 32 is coupled to a corresponding rail 22 of the second external fixation element 2 by a second strut-to-rail connector.
In one embodiment, each strut-to-rail connector forms with a corresponding rail a joint allowing at least a linear sliding movement of the strut along the rail. In one embodiment, each strut-to-rail connector forms with a corresponding rail a prismatic joint allowing linear sliding movement of the strut along the rail. In one embodiment, the prismatic joint may be any mechanism known by one skilled in the art such as for instance a threaded rod and a corresponding sleeve or a recess and a corresponding rail or ball slide guides.
In one embodiment, the strut-to-rail connector does not form with the corresponding rail a screw joint. In one embodiment, the rail is not a threaded rod. In one embodiment, the rail is a longitudinal structure having a smooth polygonal cross-section. In one embodiment, each strut-to-rail connector forms with the corresponding rail a prismatic joint with a polygonal cross-section allowing linear sliding movement of a strut relative to a corresponding rail. Said embodiment enables free translation of the struts relative to the rail; while threaded rods enable only controlled minimal translation.
In one embodiment, as depicted in FIGS. 5 to 8, the first and the second strut-to-rail connectors of each strut 3 comprise a longitudinal recess 33 designed to receive a rail 22 in a sliding manner. As well known to one skilled in the art, depending of the shape of the recess 33 or the rail 22, the rail 22 or the recess 33 respectively would have a corresponding nesting cross-sectional shape. The recess 33 and the rail 22 form a prismatic joint allowing linear sliding movement of the strut 3 relative to the rail 22 and thus linear sliding movement of each strut 3 along its corresponding rail 22 of the first and second external fixation elements (i.e. the posterior strut 3a may slide relative to the posterior rails 22a of the first and second external fixation elements 2; the medial strut 3a may slide relative to the medial rails 22a of the first and second external fixation elements 2 and the lateral strut 3a may slide relative to the lateral rails 22a of the first and second external fixation elements 2). According to one embodiment, each strut 3 may slide along the corresponding rails 22 of the first and second external fixation elements 2 without relative movement between the first and second external fixation elements 2. According to one embodiment, the strut-to-rail connector comprises a hole 34 which extends through the thickness of the connector up to the recess 33. According to one embodiment, as illustrated in FIGS. 12 and 13, the hole 34 comprises an inner thread designed to receive a screw 35 which may lock the sliding of the rail 22 within the recess 33 by screwdown. According to an alternative embodiment, the locking mechanisms for locking the prismatic joint may be any mechanism known by one skilled in the art. According to one embodiment, each strut 3 is slidable along the corresponding rails of the first and second external fixation elements independently of the other struts 3.
According to one embodiment, each strut-to-rail connector comprises a recess 33 having a longitudinal axis for receiving the rail 22 and the length of said recess 33 along its axis is ranging from 5% to 50% of the length of the rail 22 along its axis; thereby enabling sliding of each strut-to-rail connector along at least 50% of the length of the rail 22. According to one embodiment, each strut-to-rail connector comprises a recess 33 having a longitudinal axis for receiving the rail 22 and the length of said recess 33 along its axis is ranging from 5% to 40%, 5% to 30%, 5% to 20% or 5% to 10% of the length of the rail 22 along its axis.
According to one embodiment, each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis.
According to one embodiment, each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one revolute joint allowing rotation of each rail about its axis.
According to one embodiment wherein the strut-to-rail connectors coupled to the rail form a prismatic joint, the rails 22 have cross-sections preventing rotation, such as polygonal cross-sections. In one embodiment, the rails further comprise two cylindrical ends. Thus according to one embodiment, as depicted in FIG. 9, each rail 22 comprises a main portion 221 with a polygonal cross section and two ends 222 with a circular cross-section. According to one embodiment, the length of each ends 222 ranges from 0.1% to 10%, preferably from 1 to 5%, of the length of the main portion 221. According to one embodiment, as depicted in FIG. 4, each rail 22 is coupled to the corresponding plate 21 by at least one rail-to-plate connector 5. According to one embodiment, as depicted in FIG. 4, each rail 22 is coupled to the corresponding plate 21 by two rail-to-plate connectors 5, on each end of the rail 21. According to one embodiment, each rail 22 has a length along its axis between the two rail-to-plate connectors higher than 50% of the length of the corresponding plate 21 along the same axis, preferably higher than 60%, 70%, 80% or 90% of the length of the corresponding plate 21 along the same axis.
According to one embodiment, as depicted in FIG. 10, the rail-to-plate connector 5 comprises a first end 51 adapted to be coupled to a plate 21. According to an exemplary embodiment, the first end 51 comprises a hole 511 cooperating with a hole of the plate 21, thereby ensuring connection between the plate 21 and the rail-to-plate connector 5 by means of a screw. According to one embodiment, as depicted in FIG. 10, the rail-to-plate connector 5 comprises a second end 52 adapted to be coupled to a rail 22. According to an exemplary embodiment, the second end 52 comprises a circular recess 521 cooperating with the end 222 of the rail 22; thereby forming a plain bearing allowing rotation of the rail about its axis. According to another embodiment, the at least one revolute joint allowing rotation of each rail about its axis is a ball bearing.
According to one embodiment, each rail 22 is connected to the corresponding plate 21 by means of two rail-to-plate connectors 5, each comprising a first end 51 coupled to the plate 21 and a second end 52 comprising a circular recess 521 cooperating with each end 222 of the rail 22.
According to one embodiment, only one of the revolute joint of the two revolute joints formed at each end of each rail comprises a locking mechanism to lock the rotation of the rail. According to one embodiment, as depicted in FIG. 12, one of the cylindrical ends of the rails 22 extends out of the circular recess 521 and comprises a thread such that said revolute joint may be locked with a nut 25 by screwing down.
In one embodiment, the first and the second strut-to-rail-connectors of each strut are integral with said strut. In another embodiment, at least one of the strut-to-rail connector of at least one of the strut is not integral with said strut. According to said embodiment, as depicted in FIGS. 6 to 8, at least one of the struts 3 is connected to one of the strut-to- rail connector by a connecting mechanism comprising a revolute joint allowing rotation of said strut-to-rail connector with respect to the strut about the anterioposterior axis. According to one embodiment, at least one strut 3 (e.g. the posterior strut 3a) further comprises a revolute joint allowing rotation of one of the strut-to-rail connector about the anteroposterior axis. According to one embodiment, a single strut 3 of the external fixation system comprises a revolute joint allowing rotation of one of the first or the second strut-to-rail connector about the anteroposterior axis. Said embodiment enables the rotation about the anteroposterior axis of one of the external fixation element 2 while the second external fixation element 2 maintains its orientation. According to one embodiment, said revolute joint may be any revolute joint known by one skilled in the art such as plain bearings or ball bearings. According to one embodiment, said revolute joint is formed by a pin extending from the strut-to-rail connector through a corresponding hole 36 of the strut. According to one embodiment, said pin further extends out of the struts, on the opposite side, with a thread such that said revolute joint may be locked with a nut by screwing down.
In another embodiment, the strut-to-rail connectors comprise a cylindrical recess and the rails are cylindrical such that each strut-to-rail connector forms with the corresponding rail a cylindrical joint. In said embodiment, the rail-to-plate connectors 5 of the posterior, medial and lateral portions do not comprise revolute joints.
Once the dislocation has been partly reduced, it may be useful to refine the dislocation with fine and incremental movements of the first external fixation element with respect to the second external fixation element within the anteroposterior and the mediolateral directions. Therefore, according to one embodiment, as depicted in FIG. 11, at least one rail 22 further comprises two sliding carriages 29, one on each side of the telescopic strut 3. Said sliding carriages 29 slide relative to the rail and the distance between said two sliding carriages 29 is defined and fixed by the two ends of a worm screw 28. The worm screw 28 passes through a threaded hole of the struts 3. Said sliding carriage 29 may be fixed relative to the rail 22 with at least one locking mechanism. Thus when the strut 3 is almost correctly positioned, the sliding carriages 29 are fixed relative to the rail 22 and the worm screw 28 is screwed such as to refine the positon of the strut 3 with respect to the sliding carriage in a fine and incremental manner.
In one embodiment, the external fixator is configured such that the first external element is moveable relative to the second external fixation element in at least 3 degrees of freedom, especially, the first external element can at least translate relative to the second external element independently in the anteroposterior direction, in the mediolateral direction and in the superoinferior direction. Said technical feature enable the reduction of dislocation within each direction separately. With devices of the prior art wherein the movement in the three directions are not independent, reduction of the dislocation within one direction may increase the dislocation within another direction.
In addition, in an embodiment, the first external fixation element may rotate relative to the second external fixation element about the anteroposterior direction. In one embodiment, the first external fixation element cannot rotate relative to the second external fixation element about the superoinferior direction. In one embodiment, the first external fixation element cannot rotate about the mediolateral direction relatively to the second external fixation element.
In one embodiment, each joint of the external fixation system comprises a single degree of freedom. In one embodiment, each joint of the external fixation system comprises a locking mechanism for locking its single degree of freedom. According to one embodiment, said locking mechanism may be a nut. According to another embodiment, said locking mechanism may be a cam lever, preferably a cam lever with a removable lever; such as to prevent unintentional untighten. In one embodiment, the relative movement of the first and second external fixation elements may be fully locked (i.e. in translation and rotation) by locking only three joints namely:
the revolute joint between one of the posteriors rail 22a and the corresponding rail- to-plate connector;
the revolute joint between one of the lateral or medial rails 22b, 22c and the corresponding rail-to-plate connector; and
the superoinferior translation of one of the medial or lateral telescopic strut 3.
Within said embodiment, when the three joints are locked, sliding of the struts along the corresponding rails may still be activated.
According to one embodiment, as depicted in FIGS. 14 and 15, the external fixation system further comprises a plurality of fastening mechanisms 4 that are configured to attach a bone segment to an external fixation element 2, especially to attach a first bone segment to a first external fixation element and a second bone segment to a second external fixation element such that as the first and second external fixation elements move relatively to one another, the first and second bone segments also move relatively to one another. In one embodiment, the fastening mechanisms 4 are configured such that the external fixation element 2 and the bone segment are translationally and rotationally coupled. In one embodiment, the fastening mechanism 4 comprises a bracket that can be attached to the external fixation element 2 by any means known by one skilled in the art such as for instance a fastener, an axis locked by a stop pin, a pressure screw, a nut, a quick lock system or a clamp collar. In one embodiment, the fastening mechanism 4 further comprises a bone fixation element that couples the bracket to the bone such as pins. In one embodiment, the bone fixation element is attached to the bracket by any means known by one skilled in the art such as for example a fastener, a pressure screw, a quick lock system or an adhesive material. In one embodiment, the fastening mechanism 4 may be coupled to holes 23 of a plate 21 or may be mounted in a sliding manner within a slot 24 of a plate 21. In the latter embodiment, the fastening mechanism 4 may be translated along the plate 21 to be positioned easily at the right place by the surgeon. According to one embodiment, the fastening mechanism 4 may be rotated with respect to the plate 21. According to one embodiment, if the pin will not be positioned within the plane of the external fixation system, the fastening mechanism 4 further comprises a revolute joint (see FIG. 14). According to one embodiment, the fastening mechanism 4 comprises at least one tab extending within the plate 21 preventing rotation of the fastening mechanism 4 with respect to said plate 21.
In one embodiment, as depicted in FIG. 20, the external fixation system further comprises at least a third external fixation element 2 arranged at a distance to the first and the second external fixation elements 2, wherein the at least third external fixation element is coupled to the first or the second external fixation elements by a plurality of struts. According to one embodiment, the third external fixation element is identical to one of the first or second external fixation elements. According to one embodiment, the third external fixation element is different to the first and second external fixation elements. According to one embodiment, the third external fixation element comprises at least one fixation point suitable for receiving one pin. Said embodiment may be useful for maximum stability as one pin may be as close to the fracture as possible and one other pin may be as far from the fracture as possible.
In one embodiment, the external fixation system, especially the external fixation elements and/or the telescopic struts, can be manufactured in various sizes and length, depending for instance on adult or pediatric use.
According to one embodiment, in order to provide support for bone fixation elements all around the bone while facilitating insertion of the device, at least one of the external fixation element 2 comprises a longitudinal plate connected by a revolute joint to a U- shaped external fixation element; said revolute joint enabling rotation within the plane of the U-shaped external fixation element. As depicted in FIG. 21, the external fixation system 2 comprises a revolute joint between the anterior plate and the medial plate 21b. The lateral end of the anterior plate further comprises at least one hole 26 through which at least one pin 27, sliding within the anterior end of the lateral plane 21c, may be inserted; thereby locking the rotation. In one embodiment, the external fixation system, especially the telescopic struts 3, are made of a radiolucent material such as a polymer, for instance poly ether ether ketone (PEEK). In one embodiment, the material of the external fixation system is selected from a polymer, a plastic, a reinforced plastic, a plastic-carbon composite or a fiber resin composite. In one embodiment, the material of the external fixation system is selected from steel alloy, aluminum alloy, titanium alloy or magnesium alloy.
According to one embodiment, the external fixation system is applied to the tibia, the fibula, the foot, the calcaneus, the talus, the Chopart joint, the Lisfranc joint, the ankle, the femur, the humerus, the radius, the ulna, the hand or the forearm. In one embodiment, as depicted in FIGS. 16 to 19, after the first and second external fixation elements are secured to the first and second bone segments in a first configuration, a treatment plan can be performed to move the first and second external fixation elements into a second orientation. In the second orientation, the first and second bone segments are in a desired position.
Thus, the present invention also relates to a method of reducing dislocation comprising the following steps:
1. inserting the external fixation system according to the invention around first and second bone segments; said bone segments being dislocated;
2. inserting a first pin within a first bone segment through a fastening mechanism on a first external fixation element;
3. tightening the fastening mechanism;
4. centering the second external fixation element with respect to the second bone segment;
5. inserting a second pin within a second bone segment through a fastening mechanism on a second external fixation element;
6. tightening the fastening mechanism;
7. if needed, repeat steps 2 and 3 or 5 and 6 with other pins;
8. performing front and profile medical imaging;
9. reducing the dislocation; 10. tightening a first time with three locking mechanisms, namely:
- the locking mechanism of the revolute joint between one of the posteriors rail and the corresponding rail-to-plate connector;
- the locking mechanism of the revolute joint between one of the lateral or medial rails and the corresponding rail-to-plate connector; and
- the locking mechanism of the superoinferior translation of one of the medial or lateral telescopic strut;
11. performing medical imaging in order to confirm reduction;
12. if needed, repeat steps 8 to 11 until the reduction is reduced;
13. tightening all the remaining locking mechanisms.
Especially, according to one embodiment, the present invention relates to a method of reducing ankle dislocation of a subject comprising the following steps:
1. inserting the external fixation system according to the invention around the foot of a subject; said external fixation system comprising three external fixation elements (see e.g. FIG. 20);
2. inserting an half -pin within the tibia of the subject at the level of a first external fixation element; through a fastening mechanism on the medial plate;
3. tightening the fastening mechanism;
4. inserting an half-pin within the tibia of the subject at the level of a second external fixation element; through a fastening mechanism on the anterior plate;
5. tightening the fastening mechanism;
6. centering a third external fixation element with respect to the foot;
7. inserting a trans-osseous pin within the calcaneus at the level of the third external fixation element; through an fastening mechanism on the medial plate, the calcaneus and a fastening mechanism on the lateral plate;
8. tightening the two fastening mechanisms;
9. inserting an half-pin within a metatarsus of the subject at the level of the third external fixation element; through a fastening mechanism on the medial or lateral plate; 10. tightening the fastening mechanism;
11. repeat steps 9 and 10 if a wire in another metatarsus is needed;
12. reducing the dislocation;
13. tightening the external fixation system with three locking mechanisms, namely:
- the locking mechanism of the revolute joint between one of the posterior rails and the corresponding rail-to-plate connector;
- the locking mechanism of the revolute joint between one of the lateral or medial rails and the corresponding rail-to-plate connector; and
- the locking mechanism of the superoinferior translation of one of the medial or lateral telescopic struts;
14. performing profile medical imaging;
15. unlocking the locking mechanism of the revolute joint between the posterior rails and the corresponding rail-to-plate connectors;
16. refining the reduction along the anteroposterior direction;
17. locking the locking mechanism of the revolute joint between one of the posteriors rail and the corresponding rail-to-plate connector;
18. if needed, repeat steps 14 to 17 until the reduction along the anteroposterior direction is as expected;
19. performing front medical imaging;
20. locking the locking mechanism of the superoinferior translation of the posterior strut;
21. unlocking the locking mechanism of the superoinferior translation of the medial and lateral telescopic struts;
22. unlocking the locking mechanism of the revolute joint between the lateral and medial rails and the corresponding rail-to-plate connectors;
23. refining the reduction along the mediolateral direction;
24. locking the locking mechanism of the superoinferior translation of one of the medial or lateral telescopic strut; 25. locking the locking mechanism of the revolute joint between one of the lateral or medial rails and the corresponding rail-to-plate connector;
26. if needed, repeat steps 19 to 25 until the reduction along the mediolateral direction is as expected;
27. tightening all the remaining locking mechanisms.
According to one embodiment, the dislocation is located at the lower part of the tibia, fibula, talus and calcaneus.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an external fixation system 1 according to one embodiment of the invention.
Figure 2 is a perspective view of the posterior, medial and lateral plates 21a, 21b, 21c of an external fixation element 2 according to one embodiment of the invention.
Figure 3 is a perspective view of the posterior, medial and lateral plates 21a, 21b, 21c of an external fixation element 2 according to another embodiment of the invention.
Figure 4 is a top view of an external fixation system 1 according to one embodiment of the invention.
Figure 5 is a perspective view of a telescopic strut 3 according to one embodiment of the invention. Figure 6 is a perspective view of a telescopic strut 3 according to one embodiment of the invention.
Figure 7 is a perspective view of the telescopic strut 3 of figure 6. Figure 8 is a front view of the telescopic strut 3 of figure 6.
Figure 9 is a perspective view illustrating a rail 22 according to one embodiment of the invention. Figure 10 is a perspective view of a rail-to-plate connector 5 according to one embodiment of the invention.
Figure 11 is a perspective view of a strut 3 and a corresponding rail 22 according to one embodiment of the invention. Figure 12 illustrates a side view of the external fixation system 1 according to one embodiment of the invention.
Figure 13 is a front view of an external fixation system 1 according to one embodiment of the invention.
Figure 14 illustrates a fastening mechanism 4 according to one embodiment of the invention.
Figure 15 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention.
Figure 16 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention, in use wherein a subject has a dislocated ankle. Figure 17 illustrates a front view of an external fixation system 1 according to one embodiment of the invention, in use wherein a subject has a dislocated ankle.
Figure 18 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention, in use wherein the ankle dislocation has been reduced. Figure 19 illustrates a front view of an external fixation system 1 according to one embodiment of the invention, in use wherein the ankle dislocation has been reduced.
Figure 20 illustrates a perspective view of an external fixation system 1 according to one embodiment of the invention.
Figure 21 is a perspective view of the posterior, medial and lateral plates 21a, 21b, 21c of an external fixation element 2 according to one embodiment of the invention. RFERENCES
1 - External fixation system
2 - External fixation element
21 - Plate
21a - Posterior plate
21b - Medial plate
21c - Lateral plate
22 - Rail
221 - Main portion of the rail
222 - Ends of the rail
22a - Posterior rail
22b - Medial rail
22c - Lateral rail
23 - Hole
24 - Slot
24a - Posterior slot
24b - Medial slot
24c - Lateral slot
25 - Nut
26 - Hole
27 - Pin
28 - Wormscrew
29 - Sliding carriage
3 - Telescopic strut
31 - First end of the telescopic strut
32 - Second end of the telescopic strut
33 - Recess
34 - Hole
35 - Screw
36 - Hole
4 - Fastening mechanism
5 - Rail-to-plate connector

Claims

An orthopedic external fixation system comprising:
- at least a first and a second external fixation elements (2) arranged at a distance to each other, each comprising at least
- a posterior portion comprising a posterior plate (21a) and a posterior rail (22a) having a mediolateral axis;
- a medial portion comprising a medial plate (21b) extending from the posterior plate (21a) and a medial rail (22b) having an anteroposterior axis;
- a lateral portion comprising a lateral plate (21c) extending from the posterior plate (21a) and a lateral rail (22c) having an anteroposterior axis, the lateral and the medial rails (22b, 22c) being parallel;
- a posterior telescopic strut (3a) having a first and a second ends (31, 32), the first end (31) coupled to the posterior rail (22a) of the first external fixation element by a first strut-to-rail connector and the second end (32) coupled to the posterior rail (22a) of the second external fixation element by a second strut-to-rail connector;
- a medial telescopic strut (3b) having a first and a second end (31, 32), the first end (31) coupled to the medial rail (22b) of the first external fixation element by a first strut-to-rail connector and the second end (32) coupled to the medial rail (22b) of the second external fixation element by a second strut-to-rail connector;
- a lateral telescopic strut (3c) having a first and a second end (31, 32), the first end (31) coupled to the lateral rail (22c) of the first external fixation element (2) by a first strut-to-rail connector and the second end (32) coupled to the lateral rail (22c) of the second external fixation element by a second strut-to-rail connector;
wherein each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one joint allowing rotation of each rail about its axis; and wherein each of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts (3a, 3b, 3c) forms with the corresponding rail a joint allowing linear sliding movement of the posterior, medial and lateral telescopic struts along respectively the posterior, medial and lateral rails of the first and second external fixation elements.
The external fixation system according to claim 1, wherein each of the posterior, medial and lateral portions of the first and second external fixation elements comprises at least one rail-to-plate connector forming with the rail of respectively the posterior, medial and lateral portions of the first and second external fixation elements a revolute joint allowing rotation of each rail about its axis.
The external fixation system according to claim 1 or claim 2, wherein each of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts (3a, 3b, 3c) forms with the corresponding rail a prismatic joint allowing linear sliding movement of the posterior, medial and lateral telescopic struts along respectively the posterior, medial and lateral rails of the first and second external fixation elements.
The external fixation system according to claim 3, wherein each revolute and prismatic joint comprises means for locking the sliding of the prismatic joints and the rotation of the revolute joints and wherein the relative movement of the first and second external fixation elements is locked by locking at least three joints:
- one revolute joint between one of the posterior rails (22a) and the corresponding rail-to-plate connector;
- one revolute joint between one of the lateral or medial rails (22b, 22c) and the corresponding rail-to-plate connector; and
- the translation of one of the medial or lateral telescopic struts (3b, 3c).
The external fixation system according to anyone of claims 2 to 4, wherein each of the posterior, medial and lateral portions of the first and second external fixation elements comprises two revolute joints allowing rotation of each rail about its axis; said two revolute joints comprising a rail and two rail-to-plate connectors coupling the ends of the rail (22) of each of the posterior, medial and lateral portions of the first and second external fixation elements to respectively the plate (21) of each of the posterior, medial and lateral portions of the first and second external fixation elements.
The external fixation system according to anyone of claims 1 to 5, wherein the rail (22) of the posterior, medial and lateral portions of the first and second external fixation elements has a length along its axis longer than 50% of the length of respectively the plate (21) of the posterior, medial and lateral portions of the first and second external fixation elements along the same axis.
The external fixation system according to anyone of claims 1 to 6, wherein the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts (3a, 3b, 3c) comprise a recess (33) for receiving the rail (22) of the posterior, medial and lateral portions of the first and second external fixation elements and wherein the length of each of said recess (33) is less than 50% of the length of the rail along its axis; thereby enabling sliding of the first and the second strut-to-rail connectors of each of the posterior, medial and lateral telescopic struts along at least 50% of the rails length (22) of each of the posterior, medial and lateral rails of the first and second external fixation elements.
The external fixation system according to anyone of claims 1 to 7, wherein each of the posterior, medial and lateral telescopic struts (3a, 3b, 3c) are slidable along respectively the posterior, medial and lateral rails (22a, 22b, 22c) of the first and second external fixation elements independently of another of the posterior, medial and lateral telescopic struts (3a, 3b, 3c).
The external fixation system according to anyone of claims 1 to 8, wherein the posterior telescopic strut (3a) further comprises a revolute joint allowing rotation of one of the strut-to-rail connectors about the anteroposterior axis.
The external fixation system according to anyone of claims 1 to 9, wherein at least one of the first and second external fixation elements is a rectangle.
11. The external fixation system according to anyone of claims 1 to 10, further comprising at least a third external fixation element arranged at a distance to the first and the second external fixation elements, wherein the at least third external fixation elements are coupled to the first or the second external fixation elements by a plurality of struts.
12. The external fixation system according to anyone of claims 1 to 11, wherein the first and second external fixation elements comprise a plurality of holes along the posterior, medial and lateral plates (21a, 21b, 21c).
13. The external fixation system according to claim 12, further comprising a plurality of fastening mechanism (4) adapted to be received in the plurality of holes and to link the first and second external fixation elements to respectively a first and a second bone segment.
14. The external fixation system according to anyone of claims 1 to 11, wherein the first and second external fixation elements comprise a slot (24) along each of the posterior, medial and lateral plates (21a, 21b, 21c).
15. The external fixation system according to claim 14, further comprising a plurality of fastening mechanism (4) adapted to be received in a sliding manner in the slots (24) and to couple the first and second external fixation elements to respectively a first and a second bone segments.
PCT/EP2016/062028 2015-05-29 2016-05-27 External fixation system Ceased WO2016193154A1 (en)

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GB2573000A (en) * 2018-04-19 2019-10-23 Metlase Ltd External Fixator
GB2573000B (en) * 2018-04-19 2020-04-15 Metlase Ltd External Fixator

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