FR2885026A1 - "ADJUSTABLE ANGULAR TIBIAL OSTEOTOMY CAGE" - Google Patents

Abstract

The invention relates to a device for the reaxation of a knee affected by varus deformation. The implant is characterized by a metal osteotomy cage 1 provided with a large zone of bone ingrowth, and adjustable angular correction. The design of the prosthesis shown in FIG. 1 is determined by the profile of the medio-lateral and posterior faces of the tibia. The adjustment of the angulation is carried out for example with the screw 4 adjusting the maximum height h 1 of the angulation, and on the other hand with the screws 5 controlling the height h 2 and the adjustment of the parallelism of the faces 2 and 3 , compared to the osteotomy plane. The faces 2 and 3 of the prosthesis are secured by the screws 6. Said screws lock the system after adjusting the angulation. The prosthetic body 1 is preferably made of titanium T A 6 V, and coated PAH for the fusion of the interfaces. The faces 2 and 3 are pierced with holes in the appropriate areas of a diameter of 0.5 mm, for example, to promote bone recolonization, and the adhesion of surfaces.

Description

The invention relates to a device for the reaxation of a knee affected by a

  deformity in varus, and likely to be inserted in the opening of an osteotomy. The indication for which this type of implant is used, is generally due to knee osteoarthritis which concerns the internal part of the femoral tibial joint.

  The correction of this deformation, involving a recovery of the axis of the leg previously calculated preoperatively, is performed using various materials. Prostheses hitherto made to obtain the angular correction, are bone grafts do not allow early support, shims tibial osteotomies generating significant space in the opening of the osteotomy, reducing the area of bone ingrowth.

  On the other hand, the external correction systems centered on the axis of the vertical ridge with implantation of associated bone grafts, offer only a partially satisfactory support on the medial and interosseous edge, and a possibility of loss of correction. after explantation of the material.

  The object of the present invention is to provide a biologically compatible implantable device, characterized by a metal osteotomy cage, provided with a large area of bone healing, adjustable angular correction at its maximum height as at the hinges , and maintaining correction during bone healing, thus allowing early support.

  This device makes it possible according to its design, the passage of an anchor pad of a total knee prosthesis, in case of subsequent recovery of the indication, and in principle a definitive implantation.

  The prosthesis can support a load for compressive stresses of at least 140 kg.

  The design of the prosthesis, which is determined according to the profile of the medio-lateral and posterior faces of the tibia, generates a good support on the compact bone, and has a slight asymmetry on both sides of its central anteroposterior axis.

  The material preferably used for its realization is titanium T A 6 V. The osteotomy cage is coated with a PAH surface treatment, to allow the fusion between the bone and the metal parts. The upper and inner faces are pierced with holes of a diameter of 0.5 mm, for example, to promote bone recolonization, and the adhesion of surfaces.

  The prosthesis, which is very perforated, represents a volume in the opening of the osteotomy that is not very significant, and unlikely to generate complaints from patients.

  The description and its embodiment that follow are given as indicative 10 and not limiting.

  According to the description: Figure 1: Figure 1 is a schematic perspective view in which the prosthetic body 1 which is shown at the lower osteotomy line of the tibia, has a final height of about 12 mm, corresponding substantially at an angulation of the order of 14. The length corresponding to the medio-lateral bulk L is approximately 38 to 45 mm, and the width I corresponding to the anteroposterior bulk, has a value of the order of 1.8 mm to 2.5 mm. The variation of these dimensions are materialized for example by 3 sizes of osteotomy cage whose angulation is adjustable from about 8 to 14. The upper face 2 and the lower face 3 of the prosthesis are made integral by 2 male locking screws 6, and screwed into the female supports 7.

  The said faces are pierced with holes 8 for optimal bone ingrowth. The central screw 4 adjusts the dimension h1 which is the maximum height of angulation, said screw being centered approximately on the horizontal axis of the vertical ridge C. The lateral screws 5 regulate the height h2, which make it possible to adjust the faces 2 and 3 in parallel with the osteotomy opening.

  FIG. 2 is a view in axial axial section of the central screw 4. The segment D1 corresponds on the one hand to the housing of the screw head 4 and its thread D3, and on the other hand to the space D4 in which said threading takes its place.

  The segment D1 is integral with the lower face 3 of the prosthesis. The screw head D 2 serves as a conical buffer, thus removing the angulation between the faces 2 and 3 when its thread D3 is screwed progressively into the compartment D4. The input of screws E / V integral with the face 3, is in abutment with the base of the screw head after complete screwing, and the spacing generated between the faces 2 and 3 equals 14 angulation. A second female thread F1 is located in the central horizontal axis of the screw head 4, in order to secure an extractor impactor I with male thread F2, and giving the possibility of subsequently associating the prosthetic body 1 with osteosynthesis material. .

  Figure 3: Figure 3 is a front view of the face 2, which is equivalent to the level of the profile to the face 3. The hinge screws 5 converge by their longitudinal axes approximately at the level of the screw 4.

  Figure 4: Figure 4 is an axial sectional side view of the lateral adjustment screws 5 adjusting the anteroposterior parallelism of the faces 2 and 3, relative to the osteotomy plane. The head of the screws 5 so-called C 2 spreads or approximates according to the same principle mentioned in FIG. 2, the angulation of the hinges. It is also the face 3 which is secured to the screws 5. Therefore, the angulation increases when the screw head C 2 and its male thread C 3 back in the compartment C 4.

  Figure 5: Figure 5 is a front view of the screw 4, the vertical axis is approximately centered on the vertical ridge of the tibia. Markings engraved on the face of the screw head 4 as on the prosthetic body 1, precisely identify the appropriate angulation. 10

  The male threads D 3 and female D 4 allow, during a rotation at 90, a change of angulation value of 2 degrees in 2 degrees.

  The reference E 8 is a significant reference, and in practice useful given the size of the screw head 4.

  Assembly principle: A biplane osteotomy can be performed to implant the prosthetic body 1. That is to say that it comprises two parts: A horizontal part which cuts the shin from inside to outside until on the external cortex, keeping this one as a hinge, and an oblique part which is situated at the posterior face of the tuberosity, and which joins the first osteotomy. This osteotomy is performed with an oscillating saw.

  One feels and tests with the hand resistance to the opening of the tibia. As soon as it yields, we stop sawing, the ideal being to keep a hinge almost complete. Small bone fragments from the bone section are collected for subsequent insertion into the osteotomy cage.

  The 3 test templates allow an evaluation of the anteroposterior and medio-lateral crowding of the prosthetic body 1 to be implanted.

  The side screws 6 are previously sufficiently unscrewed to be able to adjust the screws 4 and 5, while maintaining the integral faces 2 and 3.

  A temporary staple can be put in place to maintain the osteotomy opening once the correction is determined.

  The prosthesis is inserted into the osteotomy opening, and the final adjustments are made. When the height of angulation is filled, it is necessary to rotate laterally on both sides of the medio-lateral space the osteotomy cage, in order to lock the system by the screws 6.

  The osteotomy cage is finally secured by an osteosynthesis material secured to the thread F 1.

Claims (1)

  1 osteotomy implant characterized in that it comprises a prosthetic body 1 materialized by a very perforated osteotomy cage, with adjustable adjustment of the angulation, for the correction of a leg axis affected by a deformation in varus.   Claim 2 Osteotomy implant according to Claim 1, characterized in that it comprises an adjustment of the angulation represented for example by the adjustment of the screw 4.   Claim 3 Osteotomy implant according to Claim 1 and 2, characterized in that it comprises an adjustment of the hinges for example with the screws 5, vertically controlling the adjustment of the parallelism of the faces 2 and 3 with respect to the osteotomy plane. .   Claim 4 Osteotomy implant according to claim 2 and 3, characterized by the transverse mounting of the screws 4 and 5 to obtain the adjustment of the vertical angulation of the device.   Claim 5 Osteotomy implant according to claim 1, characterized by the design of the faces 20 and 3 shown in Figure 3, and determined according to the profile of the medio-lateral and posterior faces of the tibia.   Claim 6 Osteotomy implant according to any one of claims 1, 2, 3, comprising two faces secured for example by the vertical screws 6 for adjusting and locking the device.   Claim 7 Osteotomy implant according to claim 1, comprising on the faces 2 and 3, holes with a diameter of for example 0.5 mm, promoting bone recolonization, and the adhesion of the surfaces.   Claim 8 An osteotomy implant according to claim 1, comprising a portion integral with osteosynthesis material, for example through a thread.