EP0959766A1 - Procede pour mesurer la solidite de la consolidation d'une fracture osseuse fixee a l'aide d'elements de fixation, et appareil associe - Google Patents

Procede pour mesurer la solidite de la consolidation d'une fracture osseuse fixee a l'aide d'elements de fixation, et appareil associe

Info

Publication number
EP0959766A1
EP0959766A1 EP97928126A EP97928126A EP0959766A1 EP 0959766 A1 EP0959766 A1 EP 0959766A1 EP 97928126 A EP97928126 A EP 97928126A EP 97928126 A EP97928126 A EP 97928126A EP 0959766 A1 EP0959766 A1 EP 0959766A1
Authority
EP
European Patent Office
Prior art keywords
ring
measuring
bone
fracture
studs
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.)
Withdrawn
Application number
EP97928126A
Other languages
German (de)
English (en)
Inventor
Henning J. Windhagen
Michael J. Raschke
Original Assignee
Novo Nordisk AS
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 Novo Nordisk AS filed Critical Novo Nordisk AS
Publication of EP0959766A1 publication Critical patent/EP0959766A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • 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, setting implements or the like
    • A61B17/60—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like for external osteosynthesis, e.g. distractors, contractors
    • A61B17/62—Ring frames, i.e. devices extending around the bones to be positioned
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/06—Measuring instruments not otherwise provided for
    • A61B2090/064—Measuring instruments not otherwise provided for for measuring force, pressure or mechanical tension

Definitions

  • the invention relates to devices for fixation of the bone ends at each side of a fracture.
  • US 5 339 533 describes a system for measuring the stiffness of a healing fractured bone.
  • the fixation device is dismounted and replaced by a bending stress goniometer. With one end of the fractured bone resting on a load cell the fractured part is pressed until a bending of 0.5 - 1 ° is obtained and the load on the load cell is recorded. After the measuring 0 the fixation rod is remounted unless the measuring shows that the bone has obtained sufficient strength so that further treatment can be stopped.
  • a repetitive dismounting and remounting of the fixture means risk of dislocation of the bone ends when they are not supported by an external fi ture and during the remounting.
  • a first and a second ring member each forming at least a part of a circular ring
  • fixing pins extending radially inwards from each of the two ring shaped members to establish a rigid connection between the respective ring members and the bone at the respective sides of the fracture
  • one of the ring members is a two-piece member composed of a first and a second ring elements which are joined together so that they can be rotated but not axially displaced relative to each other, the first ring element carrying the studs and the second ring element carrying the fixing pins, and fixing means being provided by which the first and the second ring elements can be fixed to each other to clamp them against mutual rotation.
  • the ring members may be shaped as only parts of a rings. This makes it easier to mount the ring members as the limb with the broken bone do not have to be inserted through the ring but may be passed sideways into the ring to be positioned in the centre thereof.
  • the studs keeping the ring members in a distance from each other may according to the invention be threaded and the one-piece ring member may be clamped between nuts on the studs. This allows use of the apparatus for drawing the bone ends away from each other during the healing if necessary as the one-piece ring element may be displaced along the studs by turning the nuts clamping this element.
  • the elements forming the two-piece ring member are provided with means by which jaws of a tong shaped tool may be fastened to the respective elements.
  • the tong shaped tool may be used to rotate the two ring elements and consequently the bone ends directly or indirectly fixed to these two elements in relation to each other.
  • the tool may be provided with a measuring device by which the length of the movement of the jaws and thereby the rotational angle of the relative rotation of the two bone ends may be measured.
  • Another measuring device in the tool measures the force which was needed to provoke the measured rotation.
  • the length measuring device may according to the invention be a potentiometer mounted rigidly connected to one jaw of the tong and having its slider mechanically connected to the other jaw. Thereby the resistance measured between the electric connections to one end of the potentiometer and to its slider will be proportional with the distance the jaws are moved relative to the other.
  • a load cell provided between one of the handles of the tool and the jaw operated by this handle may provide a signal reflecting the force used to move the jaws relative to each other.
  • an appropriately programmed computer may calculate and show the rotational angle obtained as a function of the rotational moment exerted on the bone ends.
  • an electric motor may be mounted on one of the ring elements and be driving the other ring element when activated. Further force measuring means may be provided measuring the torque by which the motor rotates the other ring, and angle measuring means may be provided measuring the angle of the relative movement of the two ring elements, and stops may be provided to stop the relative movement if either the torque or the angle exceeds set values.
  • a control circuit may be provided which on basis of pre-set values and feed-back signals from the measuring means controls the motor to affect a fractured bone fixed by the fixator according to the invention with rotational loads according to a pre-set load pattern. At the same time as the loads are applied on the bone, corresponding values of torque and rotation angle are automatically measured to reflect the effectiveness of the therapy.
  • Figure 1 shows schematically a fixator according to the invention mounted on a broken bone
  • FIG. 2 shows an embodiment of the fixator according to the invention
  • Figure 3 shows a top view of the fixator in figure 2
  • Figure 4 shows a bottom view of the fixator in figure 2
  • Figure 5 shows schematically in perspective the second ring of the fixator shown in figure 2
  • Figure 6 shows schematically a tool for rotating the adjacent ends of a broken bone on each side of a fracture relative to each other and for providing electronic signals reflecting relevant parameters of said rotation.
  • FIG 1 is a broken bone 1 has a first and a second end, 2 and 3 respectively, on respective sides of the fracture which forms a gap 4 between the two ends.
  • the first end 2 of the bone is fixed to a first ring member 5 by pins 6 which are mounted in brackets 7 on the ring member 5 and are anchored in the bone end 2.
  • a second ring member 8 is composed of an inner and an outer ring element, 9 and 10 respectively.
  • the inner ring element 9 has an outer diameter corresponding to the inner diameter of the outer ring element 10 so that the inner ring element 9 forms a journal for the outer ring element 10.
  • Stop rings 11 mounted on one of the ring elements cover the circular gap 12 between the two elements prevents axial movement of the ring elements relative to each other.
  • the gap 12 may just be wide enough to form a running fit between the two ring elements 9 and 10.
  • Brackets 13 mounted on the inner ring element 9 carry pins 14 which are anchored near the second end 3 of the broken bone to fix this end to said inner ring element.
  • the outer ring element 10 carries a number or studs 15 which are mounted perpendicularly to the plane defined by said outer ring element.
  • the first ring member 5 is mounted on the studs 15 at a distance from the second ring member 8 mainly parallel with said second ring member.
  • the first ring element is mounted between two nuts 16 which are screwed onto the studs 15 which are at least at their free ends provided with a thread.
  • the apparatus serves as a fixator maintaining the two bone ends 2 and 3 in a chosen position relative to each other.
  • the screw 17 When it is wanted to measure the obtained strength of the healing fracture this may be obtained without dismount in the fixator only the screw 17 must be loosened to allow relative rotational movement of the two ring elements 9 and 10.
  • the part of the bone comprising the fracture will be the object of a torque which may be measured and set in relation to the rotational angle of the rotation causing said torque.
  • the two ring elements of a second ring member 25 may be placed beneath each other as shown in figure 2.
  • An upper ring element 20 is rotatably mounted on a lower ring element 21. Threaded studs 22 are screwed into the upper ring element 20 and is secured by lock nuts 23.
  • a first ring member 24 is fastened between sets of nuts 26 on the studs 22 passing through holes in said first ring member.
  • Figure 3 shows the apparatus in figure 2 seen from above and shows that the first ring member forms about a half circle and is provided with angular spaced holes 27.
  • the studs 22 are passed through some of these holes whereas other holes are free to accommodate brackets for holding pins by which the first ring member may be anchored to the bone end at one side of a bone fracture.
  • Figure 4 shows the apparatus in figure 2 seen from the bottom.
  • the upper and the lower ring elements forms about half a circle.
  • the upper ring element 20 projects a little over the ends of the lower ring element 21.
  • Both ring elements are provided with holes.
  • the threaded studs 22 may be screwed into some of the holes 28 in the upper ring element 20.
  • Some of the holes 29 in the lower ring element 21 may be used for mounting of brackets carrying pins which anchors the lower ring element to the bone end at the other side of the fracture.
  • Other of the holes in the two ring elements may be used for mounting a measuring tool as it shall be described below.
  • a sliding journal for the lower ring element 21 is formed by a ring 30 of a low friction material clamped to the upper ring element 20 by bolts with heads 31 which are countersunk in the low friction material not to interfere with the sliding of the lower ring 21 on the provided journal.
  • the ring 30 is provided with a circumferential groove which is engaged by a circumferential flange 31 on the lower ring element to allow relative rotational but not relative axial movements of the two ring elements. Relative rotational movement of the two ring elements may be prevented by clamping the two ring elements together by screwing screws 49 in the lower ring as shown in figure 2 to engage the ring 30.
  • Figure 6 shows schematically a tool which may be used with the fixator to rotate the two adjacent bone ends of a fractured bone relative to each other and to measure the angle of rotation and the torque exerted on the bone to obtain said rotation.
  • the tool comprises a basis 32 and a slider 33 which may be displaced relative to the basis in the direction indicated by an arrow 34.
  • the basis 32 and the slider 33 are each provided with grips, 35 and 36 respectively, which may be gripped by a hand and moved towards each other to provide said relative displacement.
  • the base is provided with two arm 37 and 38 each provided with a hole 39 and 40, respectively. In stead of the two arms one broad arm with two holes may be provided.
  • the holes 39 and 40 are provided with a spacing allowing the basis to be fixed to the lower ring by bolts through said holes screwed into the a pair of the holes 29 in the lower ring element 21. This way the basis 32 is made non rotateable relative to this lower ring element and the second ring element 25 as a whole.
  • the slider is provided with an arm 41 parallel with the arms 37 and 38 of the basis.
  • the arm is provided with an arm 41 parallel with the arms 37 and 38 of the basis.
  • the slider arm 41 with the transducer 42 is elevated over the basis so that the hook 44 of the transducer lies above the upper ring element 20 when the basis is fastened with its arms 37 and 38 abutting the lower side of the lower ring element 21.
  • the tool may be so positioned that the hook 44 can grip on one of the threaded studs 28 carried by the upper ring element 20.
  • a pin may be inserted in one of the holes 28 in the upper ring element to form a point of application for a rotating force exerted on the upper ring element 20 through the hook 44 when the grips 35 and 36 of the tool is moved towards each other.
  • a displacement transducer 47 fixed to the basis 32 and having an actuator arm 48 connected to the slider 33.
  • a displacement transducer may be formed by a linear potentiometer having its resistor fixed to one of the parts and its slider fixed to the other of the parts the relative movement of which is going to be measured.
  • the displacement transducer may be of any appropriate kind and the shown suggestion shall not form any limitation of the invention. Electric signals from the displacement transducer 47 are lead to the computer and the torque exerted on the bone is calculated as a function of the rotational displacement which has caused it.
  • the tool is described in an embodiment designed for use with the embodiment of the fixator shown in figure 2 but may of course be modified to be used with other embodiments. If connected values for measured angles and torques are plotted against each other a curve will be obtained from which the bone stiffness will be reflected by the slope of the curve. However, a number of sources of errors may influence the curve and must be compensated for. E.. the pins by which the bone ends are fixed to the ring members, may show some play in their anchoring in the bone. This will give a curve having one slope as long as the rotation only takes up the play and another slope when the bone is actually twisted. It also must be remembered that the torque causes a twisting not only of the bone but also of the fixator itself.
  • fixator rigidity has to be excluded for accurate measurements. This may be done by initially measuring the fixator stiffness at a range of loads and store the connected values for torque and the angle the fixator is twisted by this torque where after a controlling software may automatically correct measured data for the twisting of the fixator.
  • the loading being a rotational loading may be exerted through the fixator apparatus when the ring elements of the second ring is released to rotate relative to each other and an electric motor fastened to one ring element and is driving the other ring.
  • the applied torque may be reflected by the power consumption of the motor or by force transducers between the ring and the motor base.
  • the application of forces and moments may be controlled through a closed loop controlling in accordance with the healing of the fracture.

Landscapes

  • Health & Medical Sciences (AREA)
  • Orthopedic Medicine & Surgery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Surgery (AREA)
  • Medical Informatics (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Molecular Biology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Surgical Instruments (AREA)
  • Orthopedics, Nursing, And Contraception (AREA)

Abstract

La solidité de la consolidation d'une fracture osseuse est mesurée en tournant autour de leur axe les os de chaque côté de la fracture de manière relative, et en mesurant le moment de rotation nécessaire en tant que fonction de l'angle de rotation obtenu. Le dispositif utilisé comporte un premier (5) et un second (8) élément annulaire, des tiges (15) reliant ces éléments (5, 8) en les maintenant axialement à une certaine distance l'un de l'autre et des broches de fixation (6, 14) reliant de manière rigide les éléments annulaires respectifs à l'os (1) de chaque côté de la fracture. L'un des élément annulaire (8) comporte un premier (10) et un second (9) composant assemblés de manière à pouvoir tourner l'un par rapport à l'autre mais sans déplacement axial, le premier composant (10) supportant les tiges (15) et le second composant (9) portant les broches de fixation (154). Les composants (9, 10) formant le second élément annulaire (8) sont en contact avec les mâchoires respectives d'un outil en forme de pince, équipé de dispositifs de mesure (42, 47) pour mesurer la longueur de déplacement de la mâchoire et la force nécessitée pour ce déplacement.
EP97928126A 1996-06-27 1997-06-20 Procede pour mesurer la solidite de la consolidation d'une fracture osseuse fixee a l'aide d'elements de fixation, et appareil associe Withdrawn EP0959766A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DK70596 1996-06-27
DK70596 1996-06-27
PCT/DK1997/000271 WO1998000062A1 (fr) 1996-06-27 1997-06-20 Procede pour mesurer la solidite de la consolidation d'une fracture osseuse fixee a l'aide d'elements de fixation, et appareil associe

Publications (1)

Publication Number Publication Date
EP0959766A1 true EP0959766A1 (fr) 1999-12-01

Family

ID=26064491

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97928126A Withdrawn EP0959766A1 (fr) 1996-06-27 1997-06-20 Procede pour mesurer la solidite de la consolidation d'une fracture osseuse fixee a l'aide d'elements de fixation, et appareil associe

Country Status (3)

Country Link
EP (1) EP0959766A1 (fr)
AU (1) AU3253997A (fr)
WO (1) WO1998000062A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11299759A (ja) * 1998-04-24 1999-11-02 Tamotsu Tamaki 繰り返しモーメント負荷装置
EP3110353A4 (fr) * 2014-03-12 2018-01-03 Orthospin Ltd. Entretoises médicales préchargées

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE895728A (fr) * 1983-01-28 1983-05-16 Region Wallonne Represente Par Procede de controle de la stabilite d'un montage orthopedique constitue d'une barre de fixation externe utilisee pour la reduction des fractures
DE3305597A1 (de) * 1983-02-18 1984-08-30 Wilhelm 4760 Werl Schulze Richtgeraet fuer knochenbrueche
GB8730257D0 (en) * 1987-12-29 1988-02-03 Richardson J B System for measuring fracture stiffness
DE4113083C2 (de) * 1991-04-22 1998-09-03 Roland Dipl Ing Dr Med Ballier Ringfixateur für die Osteosynthese

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9800062A1 *

Also Published As

Publication number Publication date
WO1998000062A1 (fr) 1998-01-08
AU3253997A (en) 1998-01-21

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