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
  • A61B17/88—Osteosynthesis instruments; Methods or means for implanting or extracting internal or external fixation devices
  • A61B17/8802—Equipment for handling bone cement or other fluid fillers
  • A61B17/8847—Equipment for handling bone cement or other fluid fillers for removing cement from a bone cavity
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/16—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans
  • A61B17/17—Guides or aligning means for drills, mills, pins or wires
  • A61B17/1739—Guides or aligning means for drills, mills, pins or wires specially adapted for particular parts of the body
  • A61B17/1742—Guides or aligning means for drills, mills, pins or wires specially adapted for particular parts of the body for the hip
  • A61B17/175—Guides or aligning means for drills, mills, pins or wires specially adapted for particular parts of the body for the hip for preparing the femur for hip prosthesis insertion
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B19/00—Programme-control systems
  • G05B19/02—Programme-control systems electric
  • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
  • G05B19/4097—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by using design data to control NC machines, e.g. CAD/CAM
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F30/00—Computer-aided design [CAD]
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/16—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans
  • A61B17/1613—Component parts
  • A61B17/1631—Special drive shafts, e.g. flexible shafts
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/16—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans
  • A61B17/17—Guides or aligning means for drills, mills, pins or wires
  • A61B17/1739—Guides or aligning means for drills, mills, pins or wires specially adapted for particular parts of the body
  • A61B17/1778—Guides or aligning means for drills, mills, pins or wires specially adapted for particular parts of the body for the shoulder
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B2017/00526—Methods of manufacturing
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
  • A61B34/10—Computer-aided planning, simulation or modelling of surgical operations
  • A61B2034/108—Computer aided selection or customisation of medical implants or cutting guides
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/46—Special tools for implanting artificial joints
  • A61F2/4603—Special tools for implanting artificial joints for insertion or extraction of endoprosthetic joints or of accessories thereof
  • A61F2002/4619—Special tools for implanting artificial joints for insertion or extraction of endoprosthetic joints or of accessories thereof for extraction

Definitions

• the present invention relates to a drill alignment device, a method for manufacturing a drill alignment device and a method for removing bone cement, i.e. a cement plug, from a distal part of a cavity in a long bone.
• US 2008/0275566 Al for instance describes an alignment device comprising an alignment body that comprises a drill guide body and a set of sleeves that support the shaft of the reamers and end mills.
• This alignment body is attached to the outside surface of the femur by two bone saddles.
• This device however requires that a large part of the femur has to be exposed during surgery, which increases the complexity of the surgery and subsequent recovery time.
• a cannulated trial femoral component having a stem which is shaped substantially the same as the shape of a stem of the original prosthesis.
• the stem has a longitudinally extending passageway which extends from the distal end to the upper end where it forms an outlet opening. Through this passageway, a hole can be drilled for the insertion of a guidewire in the bone. After removal of the trial femoral component from the bone, the guidewire is then used for guiding reamers having a hollow stem .
• a drill alignment device for use during the removal of bone cement from a cavity resulting from the removal of a cemented prosthetic device from a long bone, such as a femur, during the revision of said prosthetic device, wherein the alignment device comprises an elongate body having a size and shape for insertion in the cavity, wherein at least a part of the outer surface of said elongate body is complementary to the corresponding inner surface of said cavity, wherein the alignment device comprises a channel extending through the elongate body between a proximal end and a distal end and wherein said channel is arranged and has a diameter suitable for receiving and guiding a reamer arranged for removing bone cement in a distal part of said cavity .
• a tapered is arranged to be fitted closely in the cavity in the bone such that its position to the patient's anatomical structure is unique and stable.
• the cavity, formed by the remaining bone cement or perhaps surrounding bone, in the long bone has a unique or patient specific shape, forming the elongate body accordingly allows a stable fit.
• the outer surface of the elongate body arranged to be in contact with the inner surface of the cavity is hereto formed complementary to the corresponding section of the inner surface. Complementary in this respect means that the two surfaces in inserted state extend adjacently without any substantial play, or at least with minimal play.
• the elongate body is most preferably arranged to allow a shape fit in the cavity, such that the elongate body is
• the drill alignment device engages the long bone in the cavity left by the removal of the prosthesis, no additional engaging surfaces on the exterior on the bone are needed. No extra exposure of the bone during surgery is therefore needed to align the reamer.
• the complementary formed outer surface of the elongate body has at least three distinct contact points with corresponding surface areas of the inner surface of the cavity to ensure in a stable fit of the alignment device in the cavity.
• the channel has a distal end and a proximal end and is there between preferably surrounded by the body of the alignment device, in particular the elongate body.
• the channel is preferably tubular shaped having ends at or near the proximal and the distal ends of the alignment device. It may be advantageously to provide the inner surface of the channel with a friction resistant coating, in case the material of the drill alignment device is not sufficiently friction resistant. Dependent on the used material for manufacturing the alignment device, it may be preferable to provide the walls of the channel with a reinforcing
• the reinforcing material for instance in the form of a surface or inner wall of the channel, can provide sufficient strength or rigidity to the device.
• said channel has a diameter of at least 5,0 mm, preferably at least 6,5 mm or more preferably at least 8,0 mm.
• the diameter of the channel is chosen. In this respect, it should be noticed that with a reamer, a tool is meant which is used to create an accurate sized hole.
• Typical reamers in the particular the head thereof, used in the removal of bone cement, for instance cement plugs, have a diameter starting from 5 mm.
• the invention relates equally well related to an alignment tool for medical devices for use during revision of a prosthetic device .
• substantially the whole outer surface of the elongate body is
• the elongate body is hereby formed congruent to the inverse of the cavity.
• At least a part of the outer surface of said elongate body is congruent to the corresponding outer surface of said prosthetic device.
• the contours of the prosthesis may be used as a basis for the design of the drill alignment device as will be
• the whole outer surface for contacting the cavity of the elongate body, the part arranged to be inserted in the cavity and arranged for contacting the cavity, is formed congruently to the corresponding surfaces of the prosthesis.
• the elongate body and the prosthesis for a large part have the same shape and size. It may for instance be possible that the elongate body has a length smaller than the
• the alignment device preferably comprises a head and is at least partly formed congruently to the prosthetic device.
• the drill alignment device is shaped similar to the prosthesis, preferably including the head.
• the head provides a reference point to the surgeon, as he is then able to position the alignment device until the head of the alignment device reaches substantially the same position as the head of the removed prosthesis.
• the complimentary or congruent surfaces then facilitate the exact fit of the alignment tool.
• the outer surface of the elongate member is not in all cases preferred to design the outer surface of the elongate member based on the outer surface of the prosthesis.
• the outer surface of the drill guide is preferably designed on the basis of the surrounding bone structures and/or bone cement to allow a stable fit of the alignment device.
• the channel device may extend rectilinear with a fixed diameter in the alignment device.
• at least the proximal end of the channel has a curvature towards a medial direction
• the trochanter would be damaged in case a reamer is inserted into this channel.
• a curvature or bent in at least the proximal end of the channel at least a part of the extension of said channel does not overlap the trochanter such that upon insertion of a reamer, the trochanter is not damaged.
• Reamers typically have a shaft showing at least some
• the channel may be bent towards for instance the medial plane while the diameter remains unchanged to allow the insertion of the reamer without damaging the neighbouring tissue. It is however also possible that the channel is tapered towards the distal end, i.e. has a decreasing diameter towards the distal end, to the predetermined diameter.
• the wider proximal end allows easy insertion of the reamer without damaging the tissue, as at least a possible trajectory of the reamer to be introduced does not protrude this surrounding tissue.
• the narrower distal end then provides sufficient guiding for the reamer such that no bone tissue is damaged while reaming.
• a length of the channel at the distal end hereto has the predetermined diameter, wherein the channel for instance widens from the end of this length towards the proximal end.
• the proximal part of the channel is tapered towards the distal end to the predetermined diameter, wherein more preferably a distal part of the channel has a length having the predetermined diameter.
• the elongate body, or stem has a tapered shape, wherein the cross sectional area decreases towards the distal end, an end face is chosen which allows said minimal wall thickness. This ensures that the alignment tool, and in particular the elongate body thereof, has sufficient structural integrity. This may thus result in an elongate body having a length shorter than the depth of the cavity or the length of the stem of the prosthesis as already mentioned above.
• a further preferred embodiment of the drill alignment device according to the invention is manufactured by a three- dimensional printing technique. Using additive manufacturing techniques, which are known as such, it is possible to manufacture an alignment device with small tolerances from a digital 3d-design.
• the drill alignment device is manufactured from polyamide.
• the invention further relates to an assembly of a drill alignment device according to the invention and a reamer.
• the drill alignment tool is hereby arranged to receive and guide said reamer.
• the invention furthermore relates to a method for manufacturing a drill alignment device for use during the removal of bone cement from a cavity resulting from the removal of a cemented prosthetic device from a long bone, such as a femur, during the revision of said prosthetic device, comprising the steps of:
• the channel has a diameter suitable for receiving and guiding a reamer, and
• the drill alignment device is designed to closely fit in the cavity in the bone.
• the design of the elongate body, the part of the alignment tool arranged for insertion in the cavity, is thereto designed using data comprising the actual geometry of the cavity.
• the surface position data preferably comprises three-dimensional data being representative of the cavity.
• the steps of designing preferably comprise designing the alignment device using computer aided design.
• said channel has a diameter of at least 5,0 mm, preferably at least 6,5 mm or more preferably at least 8,0 mm.
• the surface position data comprises data obtained from a medical scan, for instance a CT-scan, of at least the prosthetic device and the surrounding bone.
• the surface position date in this case comprises geometrical data of the patient's anatomical structures, including the implanted prosthesis.
• the alignment tool can be manufactured patient specific for allowing a close fit of the device as discussed in detail above.
• Such data may be obtained from a scan as
• Prosthetic devices in general have a generic, i.e. non patient specific, shape. As the cavity in the bone is shaped to this prosthesis, it is possible to shape a corresponding drill alignment device based on the shape of prosthesis to be revised.
• elongate body comprises the steps of:
• the identified cross sectional plane forms the distal end of the elongate body.
• the length of the tapered elongate body of the drill alignment device is according to this embodiment determined by the minimum cross sectional area which is can contain, both in terms of shape and area, both the channel with its predetermined diameter and the additional surrounding predetermined wall thickness.
• the step of determining the minimal wall thickness comprises compensating for tolerances in the manufacturing process. Such toleration may include adding 0,6 - 1,0 mm to the diameters of the channel and the wall thickness.
• a further preferred embodiment further comprises the step of providing bone data comprising at least positional data of the surrounding bone and bone cement, wherein the step of designing the channel comprises aligning the channel with the middle of the distal end of the elongate body and the middle of the bone cement in the distal part of the cavity. At least the distal end of the channel is aligned such that the longitudinal axis of the channel extends through both the centre of distal plane or end of the elongate member and the centre of the cement plug.
• a further preferred embodiment further comprises the step of providing bone data comprising at least positional data of the surrounding bone, wherein the step of designing the channel comprises designing a curvature in at least the proximal part of the channel towards a medial direction based on said bone data preferably such that an extension of said channel with said curvature does not protrude the greater trochanter.
• at least the proximal end of the channel is designed such that any reamer inserted and guided through the channel will not interfere with the surrounding bone structures, in
• the curvature may include a bent, wherein the diameter of the channel is substantially the same along the length. It is however also possible, as discussed above, that the channel is tapered towards the distal end. The wider
• the step of manufacturing the designed drill alignment device comprises three-dimensional printing, preferably from polyamide. As discussed above, this allows an efficient manufacturing process, for instance based on the designs made by computer aided design.
• the invention furthermore relates to a method for designing a guide according to the invention, which can be
• the invention also relates to a computer readable memory containing data relating to the design of the guide according to the invention.
• the invention furthermore relates to a method for removing bone cement from a cavity resulting from the removal of a cemented prosthetic device from a long bone, such as a femur, during the revision of said prosthetic device, comprising the steps of:
• FIG. 1 schematically shows a cross section of a
• FIG. 2 schematically shows a femur with a prosthesis to be revised in perspective
• FIG. 3 schematically shows the femur of figure 2 in cross section along the coronal plane with the
• FIG. 10 and 11 schematically show the femur in cross section in two steps of the method for removing bone cement .
• FIG 1 a patient 1 in pre-operative state is shown.
• the left femur 2 is provided with a prosthesis 3 implanted in said femur using bone cement 4.
• the head 32, see figure 2, of the prosthesis 2 engages a corresponding cup (not shows) in the acetabulum of the pelvis 5.
• play between the prosthesis 3 and the femur 2 makes it necessary to replace the prosthesis 3 during revision surgery.
• any present bone cement 43 at the surface is removed.
• the stem 31 of the prosthesis 3 is then removed from the bone 2 by pulling the prosthesis, for instance on the head 32, proximally in a direction 100. At the location of the stem 31 of the
• a cavity 5 is left behind in the femur 2, see figure 3.
• the cavity 5 is surrounded by bone cement 4 which needs to be removed prior to preparing the femur 2 for the new prosthesis.
• the bone cement 41 radially surrounding the stem 31 can for instance be removed by scraping or reaming.
• the cement plug 42 is however more difficult to remove as any tool for removing said plug may damage the surrounding bone in case the tool is off axis. A guide for a tool for the removal of the cement plug is therefore needed.
• the guide is designed preoperatively based on a CT scan of the patient. Using image segmentation algorithms and
• the shape of the patient's anatomical structures and current prosthetic implants are determined. Therefore, in a first step of designing the guide, the design of the drill guide 6, hereafter also simply the guide, is exactly the same as the shape of the prosthesis 3, such that an exact fit in the bone 2 is assured, see figure 4.
• the guide 6 is provided with a head 63 corresponding to the size and shape of the head 32 of the prosthesis 3.
• the head 63 can be used as a reference point for the surgeon during the procedure.
• the guide 6 is furthermore provided with an elongated body in the form of a stem 61.
• the stem 61 is arranged for contacting the surfaces of the cavity 5.
• the length of the stem 61 is determined.
• a minimal cross sectional area of the stem 61 is determined based on the intended diameter D of the channel to be created in the guide 6 and a minimal wall thickness W of the guide 6 surrounding said channel, see figure 5.
• the first plane 64 is selected having a cross section perpendicular to the longitudinal axis A of the stem 61 which is large enough and is shaped to contain the channel and the surrounding wall. This plane is
• the channel 7 for receiving and guiding the channel is designed in the guide 6, see figure 7a.
• a trajectory 70 of the reamer, see figure 8a is determined which is used to cut out the channel 7 in the design of the guide 6, see figure 8b.
• the trajectory 70 hereafter also simply the channel 7, has a rectilinear distal part 7 and a curved proximal part 72.
• the distal end 71 of the channel 7 is aligned along the axis A through the centre of the distal end 64 of the guide 6 and the centre of the cement plug 42. Until an upper part 62 of the stem 61, the guide extends rectilinear through said stem 61.
• the proximal part 72 of the channel has a curvature with radius R in the medial direction.
• the radius R is chosen such that the trajectory 70, i.e. the channel and the extension thereof, does not protrude the trochanter 21.
• the diameter of the channel 7 or the trajectory 70 is at least equal to D.
• the proximal part 72b of the channel 7 is tapered towards the distal part 61 of the guide 6.
• the diameter D2 at the proximal part is therefore greater than the diameter D at the more distal part 71 of the channel 7.
• the channel has a diameter D to ensure proper guiding of the reamer.
• the proximal part 72b is also bent towards the medial plane, see the bent axis indicated with Alb.
• the wider entrance at the proximal end of the guide allows an easy insertion of the reamer, while at the same time damage to the trochanter 21 is prevented.
• the design of the trajectory 70, see figure 8a is subtracted (Boolean) from the design of the of the guide 6, which results in a guide 6 with a channel 7 as shown in cross section in figure 7a and in perspective in figures 9a and 9b. The same is of course possible for the channel as shown in figure 7b.
• the manufactured guide 6 is used to guide a tool such as a reamer 8 for the removal or drilling of the cement plug 42 in the distal part of the cavity 5, see figure 10. To this end, the guide 6 is inserted in the cavity. Due to the design of guide 6, in particular the outer surfaces of the guide 6 being complementary to the surfaces of the cavity 5, in particular the bone cement 41, the guide 6 fits exactly. This allows a stable guide 6 allowing a controlled reaming of the cement plug 42.
• the reamer 8 with a head 82 and relatively flexible shaft 81 is inserted into the channel 7 and is extended beyond the distal end of the guide 6 for reaming the cement plug 42.
• the reamer 8 in this example has a diameter of 8 mm. The reamer 8 is operated until the cement plug 42 is
• the reamer 8 is withdrawn and also the guide 6 is removed. The bone 2 is then ready for further
• processing for instance removing the remaining bone cement 41.
• the drill alignment guide in other long bones than the femur as described, such as the humerus.

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• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Surgery (AREA)
• Life Sciences & Earth Sciences (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Biomedical Technology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Heart & Thoracic Surgery (AREA)
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• Molecular Biology (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Dentistry (AREA)
• Theoretical Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Human Computer Interaction (AREA)
• Automation & Control Theory (AREA)
• General Engineering & Computer Science (AREA)
• Geometry (AREA)
• Evolutionary Computation (AREA)
• Computer Hardware Design (AREA)
• Surgical Instruments (AREA)
• Prostheses (AREA)
• Architecture (AREA)
• Software Systems (AREA)

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Citations (7)

• 2012
  • 2012-04-04 WO PCT/EP2012/056211 patent/WO2013149659A1/en not_active Ceased
  • 2012-04-04 US US14/385,891 patent/US20150216578A1/en not_active Abandoned
  • 2012-04-04 AU AU2012375997A patent/AU2012375997A1/en not_active Abandoned
  • 2012-04-04 CA CA2867858A patent/CA2867858A1/en not_active Abandoned
  • 2012-04-04 JP JP2015503762A patent/JP2015512311A/ja active Pending
  • 2012-04-04 EP EP12713955.8A patent/EP2833804A1/en not_active Withdrawn

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