Methods for selecting knee prosthesis elements and device therefor

• US 20050049524A1
• Filed: 11/04/2002
• Published: 03/03/2005
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Christian Lefevre, Eric Stindel, Jean-Louis Briard, Depuy Ireland Unlimited Company (Johnson & Johnson), Philippe Merloz
• Original Assignee: Depuy (Johnson & Johnson)
• Inventors: Breysse, Michael, Briard, Jean-Louis, Lefevre, Christian, Stindel, Eric, Merloz, Philippe
• Granted Patent: US 7,611,519 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• CPC Class Codes: A61B 17/154 for preparing bone for knee prosthesis
• CPC Class Codes: A61B 2034/102 Modelling of surgical devices, implants or prosthesis
• CPC Class Codes: A61B 2034/105 Modelling of the patient, e.g. for ligaments or bones
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2034/2072 Reference field transducer attached to an instrument or patient
• CPC Class Codes: A61B 2090/067 for measuring angles
• CPC Class Codes: A61B 2090/3983 Reference marker arrangements for use with image guided surgery
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 90/06 Measuring instruments not otherwise provided for
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2/46 Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30736 Augments or augmentation pieces, e.g. wedges or blocks for bridging a bone defect
• CPC Class Codes: A61F 2002/30952 using CAD-CAM techniques or NC-techniques
• CPC Class Codes: A61F 2002/4633 for selection of endoprosthetic joints or for pre-operative planning
• CPC Class Codes: A61F 2002/4668 : for measuring angles

Abstract

The invention concerns a method for selecting one or several knee prosthesis elements, characterized in that it consists in acquiring spatial data concerning spacing and tensioned femorotibial position, including the corresponding HKA angle, for at least three angular positions, of 20°, of 0°, and of the order of 90° in flexion, in processing the data thus obtained to verify whether the HKA angles are substantially equal and included within the tolerable limits, and in processing said data, in particular those corresponding to extension and flexion of 90° to determine the dimensions and/or positions of the implant.

Claims

1-17. -17. (canceled)

18. Method for selecting one or more knee prosthesis elements and, in particular, a prosthetic femoral portion, and/or a tibial prosthetic plate from an available set of these elements, and/or a femoral or tibial thickness template, wherein spatial data concerning the tensioned femoro-tibial spacing and position is acquired with the knee cap in position or dislocated, including the corresponding HKA angle, for at least three angular positions of the knee, namely an intermediate position flexed by approximately 20°

, and extended position, if possible with 0°

degrees of flexion, and a significantly flexed position, preferably with flexion of approximately 90°

, the information thus obtained, corresponding to the aforementioned position with reduced flexion of 20° and

the extended position, is processed to indicate whether, in these two positions, the HKA angles are substantially equal and are within the tolerable limits of genu varum and of genu valgum, and this data, in particular the data corresponding to the extension and significant flexion of approximately 90°

, is processed, to determine the sizes and/or the positions of the implant and, in particular, the choice of the thickness of the tibial insert for optimum filling of the space between the prosthetic condyle and the tibial cut and the choice of the size of the femoral implant.

19. Method according to claim 18, characterised in that the angle of intermediate flexion is an angle of 20°

±

10°

.

20. Method according to either claim 18, characterised in that the angle when extended is 0°

±

5°

.

21. Method according to claim 18, characterised in that the angle of major flexion is 90°

±

15°

.

22. Method according to claim 18, characterised in that the data is acquired in the following order:

data at 20°

, then data at 0°

, then data at 90°

.

23. Method according to claim 18, characterised in that it is verified by means of a computer that the angles at which the data is acquired actually correspond to the desired angles, acquisition being denied if the corresponding angle is not observed.

24. Method according to claim 18, characterised in that it is determined whether, at extension angles and angles of flexion of 20°

, the HKA angle is substantially equal in both positions and between 175° and

180°

in the case of genu varum and between 180° and

184°

in the case of genu valgum, and if so, it is considered that the anatomical properties are appropriate.

25. Method according to claim 18, characterised in that the processing relating to the determination of the most appropriate elements of the prosthesis of the method is not carried out until the data corresponding to 0°

and 20°

are acceptable, namely absence of substantial flexum and HKA angles which are substantially equal and within the permitted values.

26. Method according to claim 18, characterised in that the said data is processed by modelling means to determine an antero-posterior position of the femoral prosthesis which is such that:

the upper edge of the prosthetic trochlea is in contact with the anterior femoral cortical bone;

the axial rotation of the femoral prosthesis is such that the posterior prosthetic condyles are parallel to the actual tibial cut,

the tibial insert selected from the set best fills the space between the prosthetic condyles and the tibial cut;

the medio-lateral position is such that the implant is centred on the anatomical notch,

and the distal position of the femoral implant is chosen using the selected tibial plate and the extended position is stored so that the laxity is substantially zero in the extended position;

the femoral varus is such that, when extended, the distal prosthetic condyles are parallel to the tibial cut produced.

27. Method according to claim 18, characterised in that the result of the processing indicates the exact choice of the various elements of the prosthetic set.

28. Method according to claim 18, characterised in that it comprises the stage of preselection by means of controlling the parameters inherent in the set, such as the size of the femoral implant, the height of the tibial insert, the axial rotation, the femoral varus, the flexum, the antero-posterior position, the lateral position and the height of the distal femoral cut to be made.

29. Method according to claim 18, characterised in that the internal and external laxities estimated in flexion and in extension are displayed continuously, at least for the aforementioned three positions.

30. Device for carrying out the method according to claim 18, said device comprising:

a means for acquiring the spatial position of a three-dimensional spatial system of reference marks on the patient'"'"'s tibia or femur and spatial positions of marks, probes or instruments on the other bone to obtain spatial data relating to the displacement between the patient'"'"'s femur and tibia in the knee region, means preferably comprising previously obtained anatomical data on a patient'"'"'s femur and/or tibia, for determining, as a function of said spatial data, the angle of flexion between the femur and the tibia, the distance between the ends of the femur and tibia, as well as the HKA angle, processing and storage means for storing said distance and said HKA angle in combination with the angle of flexion for at least three angles of flexion, namely an angle of reduced flexion, in particular of 20°

, as defined above, an angle of extension, in particular an angle of 0°

, as defined above, and an angle of significant flexion, in particular an angle of 90°

, as defined above, means for comparing said distances and HKA angles, at least for the angle of reduced flexion and the angle of extension, storage means comprising dimensional data relating to sets of knee implant components, 3D processing means for modelling the implanted positions of said elements of implant prosthesis set, at least in the positions of angles of extension and of great flexion, and processing means for providing relevant data relating to the modelled knee implant and/or for selecting said elements of the implant set providing the best characteristic data, means for displaying said data or for selection, and means for controlling operation of the device.

31. Device according to claim 30, characterised in that said control means are designed to enable the operator to record the collected data corresponding at least to said angles of slight flexion, of extension and of pronounced flexion, said processing means verifying and validating the correct value of the angle for recording.

32. Device according to claim 30, characterised in that said control means are designed to propose that the operator chooses one or more elements of a set of prosthetic elements so as to allow said processing means to model the implantation of said elements and to provide or process the relevant characteristics for said elements in the implanted modelling position.

33. Device according to claim 30, characterised in that the control means comprise foot or voice-actuated means to enable a surgeon to control the device without having to use his hands.

34. Device according to claim 30, characterised in that the acquisition means for collecting spatial data relating to the displacements and to the relative positions of the femur and the tibia comprise a high-definition digital camera which is sensitive to the signals originating from the osseous portions of the knee, such as, for example, infrared reflective markers or optionally image detecting means.