Title of Invention

DISTAL FEMORAL PROSTHESIS WITH THRUST BEARING POLYMER PAD & ROTATING AXIS MECHANISM

Abstract

The Distal femur prosthesis with trust bearing polymer pad and rotating axis mechanism comparing of condylar component, median component, femoral shaft, tibial shaft, thrust bearing pad, thrust bearing, 2 collared bushes, sleeve bearing, pivot pin, screws with spring and washers when it assembled. The femoral shaft that anchors to the intramedullary portion of the bone at one end and that expands as the condylar component which mates to the median component. The condylar component is angled by 6 degrees at its mid portion. The UHMWPE thrust bearing pad is provided between the under portion of the distal femoral condylar component and the upper surface of the median component and serves to reduce the friction between the metallic surfaces by relocating the load transmitted to tibial component and pivot pin. The rotating hinge is assembled around the median component and is present in the tibial component and provides 3 degrees of radial rotation between the femoral and tibial components.

Full Text

This invention relates to Distal Femoral Prosthesis with Thrust Bearing Pad and Rotating Axis Mechanism. This invention relates to the Distal Femoral Prosthesis with Thrust Bearing Pad and Rotating Axis Mechanism in the field of medical technology. Further, this invention relates to a novel custom-built endoprosthesis namely the Distal Femoral Prosthesis. More particularly this invention relates to custom-built endoprosthesis Distal Femoral Prosthesis with Thrust Bearing pad and rotating axis Mechanism. Introduction Management of patients with musculoskeletal neoplasms has always been one of the most challenging areas in oncology. Prior to 1970, almost every patient with a primary malignant tumour of musculoskeletal system would not have any surgical treatment. They would not have adjuvant chemotherapy or irradiation and surgical treatment was almost an amputation with a five-year survival rate of 20%. For benign lesions such as Giant Cell Tumours, the treatment was curettage with 40-60% recurrence rate. Patients with painful metastatic lesions were managed palliatively until they were mercifully relived by death. Prior Art, Technique and Practice The conventional treatment for bone tumours over the years has been amputation which is surgical removal of the affected part of the body. Amputation led to severe disability and psychological problems. The patient was made to lose not only part of his body, but part of his personality. By the advent of limb salvage, the technique of removing the tumour only and saving the limb of the patient was developed. The aim of limb salvage in bone tumour management is to eradicate the disease, retain the integrity of the skeletal system and preserve the limb with useful functions using metallic prosthesis. The early methods of reconstruction after limb salvage used the patient's own bone from another part of the body, but were associated with severe disability due to the lack of knee motion. The technique of endoprosthetic replacement revolutionized limb salvage by providing a method of reconstruction that provides stability and mobility. The endoprostheses that is used after excision of bone tumours around the knee joint, differs from other joint replacement prosthesis because of the large lengths of bone that needs to be replaced. The endoprostheses needs to be fabricated according to the anatomical dimensions of the patient and is therefore termed as the Custom Prosthesis. The Component custom prosthesis was designed by us to meet the anatomical and functional demands after excision of bone tumours. Different types of Custom Prosthesis have been developed by us to replace bone defects after limb salvage surgery for bone tumours of the Distal femur (Thigh bone) and Proximal tibia (Leg bone) The patent application No:897/MAS/2001, which has already been submitted, is a proximal tibial prosthesis with a pivotal hinge mechanism. It has a median component, which is linked to the femoral component at one end and the tibial component on the other forming a pivotal hinge mechanism. The lower part of this median component has a horizontal bore on which two collared bushes of a biocompatible polymer, rotate. This tibial component has a hub, which slings with the horizontal bore, and is held, in position by a pivot pin and lock screw. This innovation permits about 145° of flexion, and is limited by the face of the median component abutting the face of the tibial component, about the axis of the pivot pin and hence called the pivot pin mechanism. The patent application No: 898/MAS/2001, which has also been submitted, is a distal femoral prosthesis with pivotal hinge mechanism. It has a femoral shaft, which has a femoral stem that forms the bone anchoring component on one end and mates with the condylar component the other end, which mates with the median component, forming the pivot joint mechanism. The median component houses the collared bushes forms the pivotal hinge at its upper end and the lower end, anchors to the tibial bone by means of the tibial anchoring component. The pivotal hinge mechanism is formed between the condylar and median components and it held by the pivot pin. This mechanism alarm flexing of 145° between the femoral shaft and tibial component on the dorsal side. The patent application No: 1002/MAS/2002, which has already been submitted, is a proximal tibial prosthesis with a bearing polymer pad mechanism. The provision of a polygonal weight bearing polymer pad over the lower part of the median component, which is fixed to the median component using a bearing fixing screw. The under surface of this pad has two semi circular contoured cavities to accommodate the tibial head. The median component links the femoral component and the tibial head, forming the pivot mechanism. This mechanism permits a flexion of 0-145°. .The patent application No:1002/MAS/2002 replaces the proximal tibia, and has the weight bearing polymer pad, which is already been described whereas the patent application No: 898/MAS/2001 replaces the distal part of the femur, and does not have the weight bearing polymer pad. The present patent application No: 707/CHE/2003 is a distal femoral prosthesis with thrust bearing polymer pad and rotating axis mechanism. This invention has a femoral shaft, which comprises femoral anchoring component on one end, and the other end evolves, into the cylindrical femoral component, which corresponds to the anatomy of the normal bone. The lower part of the femoral component mates with the condylar component, which is angled by 6° according to the side of the prosthesis. The interior portion of this condylar component mates with the median component by means of the pivotal pin and collared bushes. The UHMWPE thrust bearing pad is provided between the under surface of the condylar component and the upper surface of the median component. This invention also has a rotating axis mechanism, which is designed into the median component, and permits about 3° of radial rotation between the femoral and tibial component. The thrust-bearing pad serves the redistribute the load transmission and reduces friction. The rotating axis mechanism provides some degree of rotation, thus decreasing the stress at the bone implant junction and decreases the chances of loosening of the implant. This invention differs from the previous stated patent application Nos: 897/MAS/2002 and 1002/MAS/2002, because the anatomical part replaced by this invention is the lower part of the thigh bone (distal femur) whereas the above-mentioned two inventions replace the upper part of the leg bone (proximal tibia). The differentiating features between patent application No: 707/CHE/2003 and patent application No: 898/MAS/2002 are the provision of the UHMWPE thrust-bearing pad and the rotating axis mechanism in patent application No: 707/CHE/2003. In patent application no: 898/01, the ULTMWPE collar bushes are accommodated in a horizontal bore in the median component, whereas in patent application no:707/03, the bushes are placed in grooves in the condylar compound. Objects of Invention It is the primary object of the invention to invent and construct a novel -Distal Femoral Prosthesis with Knee Joint. It is yet another object of the invention to invent and construct a novel endoprosthesis - Distal Femur, which is unique. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, which mimics the physiological action of the distal part of the femoral bone. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, which would retain the functional aspects of the distal femoral bone along with the knee joint. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur which would take care of the structural loading which were encountered by the proximal part of the tibia before the lesions. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, which would preserve the distal part of the femoral bone. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, which matches in profile the anatomic region of the distal femur. It is yet another object of the invention to invent and construct a novel endoprosthesis — distal femur, which is economical. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, which is safe in usage. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, wherein the said device is provided with hinge mechanism to impart articulating motion of the knee joint. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, wherein the femoral stem tilts sideways by an angle of 6° to the left when viewed from the front side for a RIGHT configured distal femoral prosthesis. It is yet another object of the invention to invent and construct a novel endoprosthesis - distal femur, wherein the femoral shaft tilts sideways by an angle of 6° to the right when viewed from the front side for a LEFT configured distal femur. Further the objects of the invention will be clear from the following description. Preferred Embodiment of Invention The following specification will describe in detail with reference drawings accompanying the specification. The nature of the invention and the manner in which it is to be performed is clearly and sufficiently described in the complete specification. The final portion of the complete specification ends with a statement of claims, which defines the invention. Figure 1 shows isometric view of the distal femoral prosthesis in un-flexed position. - RIGHT - 1 A, LEFT - 1B. Figure 2 shows side view of the distal femoral prosthesis in un-flexed position and in full flexion. Figure 3 shows exploded view of the distal femoral prosthesis. Figure 4 shows the isometric view of the condylar component. Figure 5 shows isometric views of the thrust bearing pad mechanism:- thrust bearing pad Part No:6, median component Part No:2 , collared bushes PartNo:8, pivot pin locating screw Part No; 15 and thrust bearing pad fixing screw Part No: 12. Figure 6 shows isometric views of the thrust bearing Part No:7, the sleeve bearing Part No:9 and the tibial component Part No:4. Distal Femoral Prosthesis comprises of the following components: Basic components of the device are designated by numerals in the illustrated drawings and are referred in the description of the complete specification. The designations of various parts of the device are as follows. LEGEND OF PARTS / COMPONENTS 7. Condylar component Figure - 4 2. Median component Figure - 5 3. Femoral shaft Figure - I & 2 4. Tibial component Figure - 6 5. Pivot pin Figure - 5 6. Thrust bearing pad Figure - 5 7. Thrust bearing Figure - 6 8. Collared bushes Figure - 5 9. Sleeve bearing Figure - 6. 10. Thrust bearing fixing screw Figure - 3 11. Thrust bearing centring screw Figure - 3 12. Thrust bearing pad fixing screw Figure - 3 & 5 13. Condylar component fixing screws Figure - 3 & 4 14. Spring washer Figure - 3 15. Pivot pin Locating screw Figure - 3 & 5 The detailed description of principal parts referred herein is as follows: I. The femoral shaft (Fig - 1A), also called as the femoral stem, expands as the condylar component (1) that takes in the median component (2) to construct the thrust bearing mechanism with its UHMWPE thrust bearing pad (6). The femoral shaft anchors to the intramedullary portion of the bone by its tapered stem called the femoral anchoring component (3a-Fig.2). This stem has longitudinally oval troughs on its outer matted surface to provide adequate grip to the intramedullary bone cement. These equally wide and equally spaced troughs of the femoral stem, three in number, differ in their lengths towards the femoral shaft. The other end (3) of the femoral stem evolves into the cylindrical shaft known as the femoral component, whose size corresponds to that part of normal bone. The Condylar component (1) mates with the femoral shaft on its upper end and with the median component at its lower end (Fig.3). The upper portion of the condylar component projects as a cylindrical part (la-Fig.4) provided with two threaded holes (lg) on its anterior aspect which when assembled with the femoral shaft, falls in line with the two threaded holes of the femoral stem, thus securing both the major components, locked by the two screws (13) provided with two stainless steel spring washers (14). When viewed in the front elevation, (Fig.l) the condylar component is angled sideways (the angle between the vertical axis 1A and oblique axis IB, at its mid portion, to around 6° to the left, for a RIGHT configured prosthesis (Fig.lA). Similarly for a LEFT- configured prosthesis, the vertical axis tilts to around 6° to the right (Fig.lB). II. THRUST BEARING MECHANISM The basic function of the thrust bearing mechanism (Fig. 2) is to give the prosthesis a flexion of 145° to the dorsal side of the prosthesis. The components that form part of the thrust bearing mechanism are (Distal Femoral) Condylar Component (1), Median component (2), thrust-bearing pad (6), Pivot pin (5), Collared Bushes (8) and a Locating screw (15- Fig.3). The inferior portion of the condylar component (l-Fig.4) as it spreads out, ends as two posteriorly projected circular flanges with flattened lateral surfaces (Ik) and circular inner radial surfaces (Id) of the grooves (Ij) forming a radial groove (r) on its posterior (dorsal) aspect. Two collared bushes (8-Fig.5) made of biocompatible polymer (UHMWPE) are placed into the grooves (lj) of the condylar component (Fig.4), with the collars (8a-Fig.5) of the bushes seating on the face (2a) of the median component (Fig.5). This finds the outer surface of the collared bushes (8e) in close approximation to the inner surfaces (lm) of the two flanges of the condylar component (Fig.4). The median component (2-Fig.5) and the collared bushes (8-Fig.5) slide into the radial groove (r-Fig.4) of the condylar component such that the outer surfaces (8e) of the collared bushes and the outer surface (lm) of the flanges of the condylar component are in a single plane. This also leaves the posterior surfaces of the median component (2p-Fig.5) and that of the flanges of the condylar component in a single plane. The pivot pin (5-Fig.5) with a diameter just less than the inner diameter of the bore (8d-Fig.5) of the bushes snugly passes through them without making any surface contact with the bore (2n) of the median component. This leaves a hardly visible but important circumferential gap between the pivot pin and the groove (2n) of the median component, which equals the difference in cross-sectional diameters of (8d) and the pivot pin. The pivot pin locating screw (15), with a cylindrical non-threaded tip (15a-Fig.5), enters from the posterior into a fully-threaded aperture (2b) of the median component in a direction which is radial and perpendicular to the flanges of the median component. This direction seats the cylindrical tip (15a) on a specially designed, centrally and posteriorly placed non-threaded hole (5a) of the pivot pin without making any surface contact. The posterior portion of the aperture (2b) of the median component is widened circumferentially to accommodate the counter-sunk head (15c) of the pivot pin locating screw so that the pin just stops short of making a surface contact with the pivot pin. The pivot pin has two linear slots (5b-Fig.5) carved on its either sides, which when positioned horizontally after insertion of the pin into the grooves, brings the hole (5a) in a perfect position to receive the tip (15a) of the pivot pin fixing screw. Thus the locating screw (15) fixes the pivot pin allowing a trivial play and preventing any axial movement or slipping out. This also ensures that the folding and unfolding movements of the prosthesis bring only the inner surfaces (ld-Fig.4) of the circular flanges of the median component and the outer surfaces (8c-Fig.5) of the bushes in frictional contact with each other. This pivotal mechanism assembly in its unfolded position is at 180° (Fig.2) with respect to the pivot i.e. the longitudinal plane of the femoral component and that of the tibial component at the pivotal point is at an angle of 180°. This position is taken as zero flexion position. At zero flexion position (unfolded position) the face (2h), of the median component (Fig.5) abuts the radial groove (s-Fig.4) of the femoral condylar component, knocking against the median inferior margin (r) of the anterior surface of the condylar component acting as a stopper at this point i.e.; there will be no movement beyond this angle in the ventral side. Taking this as zero flexion point, the prosthesis will give a bending action of 145° on the dorsal side, with the pivot as the pivotal point. As the folding action of the prosthesis takes effect, i.e., on flexion at the pivot, the postero-superior surface (2p-Fig.5) of the median component starts to lie in opposition to the fanned out posterior surface (w-Fig.4) of the condylar component. III. THRUST BEARING PAD MECHANISM Objective: To increase the durability of the implant by 1. Reducing the frictional wear between metallic surfaces 2. Relocating the load transmitted to the pivot pin and the tibial component on weight bearing. The UHMWPE thrust-bearing pad (6) is provided between the under-surfaces of the condylar component (le-Fig.4) and the superior surface (2d-Fig.5) of the discoid platform (2j) of the median component (2), approximating in total contact with the outer planar surfaces (2c) of the base of the upper radial portion of the median component (Fig.5). The thrust-bearing pad has planar inferior and outer surfaces (6c), a superior plano-concave surface an anterior plano-convex surface (6d-Fig.5). The posterior portion of the pad is shaped into two limbs, which provide the concave superior surfaces (6b-Fig.5) to accommodate the convex metallic surfaces (le-Fig.4) of the two flanges of the condylar component and that of the collars (8a-Fig.5) of the two collared UHMWPE bushes (8) of the pivotal mechanism. The entire inferior planar aspect of the thrust-bearing pad rests on a slightly depressed planar portion (2d) of the platform of the median component (Fig.5). The anterior surface of the thrust bearing pad has a non-threaded hole (6e-Fig.5) running through the anterior portion, lodging the thrust bearing pad fixing screw (12-Fig.5), whose threaded tip (12a) gets fixed on a threaded hole (2i) on the anterior surface of the base of the upper radial portion of the median component (Fig.5). The locking screw has a tapered head and threaded stem, which when driven into the thrust bearing pad and the median component, helps in the readjustments to give a taut range of movement between the distal femoral component and the thrust bearing pad. When the prosthesis is folded, the raised and tapered postero-superior portions (6f-Fig.5) of the two limbs of the pad approach the posterior surface of the condylar component and the process of folding is completed when these edges close against the posterior surface forming an angle of 145° (Fig.2). IV. ROTATING AXIS MECHANISM Objective: The rotating axis provides a small degree (3°to 4°) of radial rotations, externally and internally between the femoral component and the tibial component. It is a device assembled around the median component and housed by the tibial component. Description of parts: The gadgets that form the rotating axis mechanism are the following: Median component (2), Thrust bearing (7), Thrust bearing centring screw (11), Thrust bearing fixing screws (10), Sleeve bearing (9) and the Tibial component (4-FigJ) The median component has a circumferential horizontal groove (2g-Fig.5) beneath the plane (2j) for the thrust-bearing pad. This groove, formed by the lapping of the two collars (2e & 2f) houses a thrust bearing centring screw (11) resembling a half threaded stud, in the midline of its anterior aspect. The inferior collar (2r) of the slot extends inferiorly in its centre as the lower stem (2s) of the median component with a taper (2q-Fig.5). The groove (2g) serves to accommodate the polymer thrust bearing (7), which has a vertical slit (7b) in its posterior arc and has a horizontally oriented oval slot (7e) in its anterior (Fig.5). The slit is provided to enable the thrust bearing encircle the groove that is collared on its both ends (2e & 2f). The thrust bearing neatly fits into the groove, as its inner diameter is just greater than that of the groove. The slot (7e) of the thrust bearing is placed anteriorly so as to find the thrust-bearing centring screw (11) at the midline. The arcade thus formed on either sides of the centring screw provides the required space for the median component to traverse, which in femoral and tibial stems fixed with PMMA cement to their respective bones. The inner surface (7f-Fig.6) of the thrust bearing is so designed to occupy the entire depth of the groove (2g-Fig-5) of the median component. The superior and inferior collars (2e & 2f) also rest on the superior and inferior circumferential space of the inner edge (7a & 7d) of the thrust bearing. As a result, when the thrust bearing is positioned on the median component, it firmly encloses (with its posterior slit (7b) closed) the outer and inner surfaces of the superior and inferior collars and the groove (2g) to expose only the thrust bearing centring screw (11) and the arcade on its either side (Fig.3). There are two counter dents (7c-Fig.6) placed diametrically opposite to each other on the outer surface of the thrust bearing, so as to receive the thrust bearing fixing screws (10) from the exterior of the housing wall (4b) of the tibial anchoring component (Fig.6), The median component with its thrust bearing (Comp.No:7) and the thrust bearing centring screw (Part No: 11) is seated into the tibial component with a polymer sleeve bearing (9-Fig.6), inserted into the lower stem (2q) of the median component. The outer surface of the thrust bearing (with its posterior slit closed) and the outer surface of the head of the centring screw, fit closely together into the inner diameter and through the depth of the housing wall of the tibial component (Fig.6). The thrust bearing fixing screws (10), driven radially from the outer surface of the tibial housing wall seating on the counter-dents, hold the thrust bearing from going through any rotational movement (Fig.3). This assembly leaves a small circumferential gap between the inferior surface of the discoid platform (2j-Fig.5) of the median component and the superior surface of the housing wall (4a-Fig-6) of the tibial anchoring component. Hence the load transmitted down the femoral component through the median component is transferred to the lower stem (2s) of the median component and on to the polymer sleeve bearing (9), thence to the stem (4d-Fig.lB) of the tibial anchoring component, which takes up the load from being given off to the tibial housing wall. As the housing wall rests on the cortex of the tibial bone, the mechanism described above renders the prosthesis as a load-sharing device, better suited to the lower limb than a load-bearing one (Fig.2). The sleeve bearing (9) made of UHMWPE consists of a superior disc (9c-Fig.6) with an aperture (9a-Fig.6), that extends centrally as an inferior extension (9d) that serves to absorb the load transmitted on to the inner surface of the stem (4c) of the tibial anchoring component. The outer diameter of the base of the tibial stem (4c) has to be just less than the inner (intramedullary) diameter of the proximal tibial cortex. This leaves a longitudinal hollow in its inside to house the stem (9b) of the sleeve bearing. The stem (9d) tapers on to a narrower tip (9e), which lodges tightly in the space that is available inside the tibial stem limited by the indenting troughs (4e) of the tibial stem. The surface of the tibial stem component (4d, Fig 6) has a matted finish to increase the surface area of contact ensuring a firm adherence to the cement. This stem has longitudinally oval troughs (4e, Fig 6) on its outer matted surface to provide adequate grip to the intramedullary bone cement. These equally wide and equally spaced troughs of the femoral stem, four in number, differ in their lengths towards the base (4c) of the stem. The anterior midline of the tibial housing wall has two small marking dents (4f) on its superior and inferior margins, which when assembled with the median component, falls in line with a similar small dent over the anterior aspect of the discoid platform (2j). It is to be noted that the complete specification discloses salient features of the invention. The scope and ambit of the invention is defined in the following statement claims. We Claim 1. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism comprising of a femoral shaft, a condylar component, a median component, a pivot pin, locking screw, two collared bushes, a thrust bearing, a tibial anchoring component, the said components being integrated to form a device, the device having a thrust bearing mechanism, femoral shaft being adapted to mate with the condylar component on one end, forms the bone anchoring component on the other, condylar component being adapted to mate with femoral shaft on its upper end and on its lower end, with the median component, forming the Thrust bearing mechanism, the median component housing the thrust bearing is adapted to mate with the tibial component to form the rotating axis mechanism, to impart a total rotation of 6° between the femoral shaft and the tibial component, the mechanism being to impart a flexion of 145° between the femoral shaft and the tibial component on the dorsal side and two bone-anchoring components, containing longitudinal grooves on their surfaces. 2. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the condylar component has a feature resembling the profile of the condylar region of the femoral bone itself. 3. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the Thrust bearing mechanism of the median component being fitted to the condylar groove of the condylar component with collared bushes, pivot pin and lock screw. 4. Distal Femoral Prosthesis with thrust bearing pad and rotating axis mechanism as in claim 3, wherein the said bushes act as bearings to minimize the impact of wear and give the joint a frictionless flexion. 5. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 3, where in the orientation of the collared bushes with respect to the median and the tibial components. 6. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 3, wherein the bottom tip of the lock screw nearly plugs the hole in the pivot pin, thus ensuring a positive locking and allowing for a minimal play, so as to avoid metal-to-metal contact. 7. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 3, wherein the upper tangential face of the radial groove on the dorsal side of the condylar components acts as a stopper in the zero flexion position by butting against the median component. 8. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 3, wherein the lower tangential face of the radial groove on the dorsal side of the condylar component acting as a stopper in full-flexion position by butting with the median component. 9. Distal Femoral Prosthesis with thrust bearing pad and rotating axis mechanism as in claim 1, wherein the concavity of the thrust bearing pad mates in close approximation to the convexity of the condylar flange, to minimize the impact of wear and give the joint a frictionless flexion. 10. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the tibial anchoring component is mounted on the lower face of the median component by a rotating axis mechanism. 11. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the femoral shaft tilts sideways by about 6°. 12. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 11, wherein the femoral shaft tilts to the left, when viewed from the front position for the RIGHT limb configuration. 13. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 11, wherein the femoral shaft tilts to the right, if viewed from the front position for the LEFT limb configuration. 14. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the radial groove on the ventral side of the condylar component is concentric to the pivotal holes. 15. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the rotating axis mechanism seats tightly, fixed on to the tibial component rotates the median component to 3° on either sides. 16. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the extreme tips of the femoral component and the tibial components are tangentially round in section. 17. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the three troughs of the femoral stem differ in their lengths providing adequate thickness and thereby not interfering with the strength of the base of the bone anchoring component. 18. Distal Femoral Prosthesis with Thrust bearing pad and rotating axis mechanism as in claim 1, wherein the four grooves of the tibial stem differ in their lengths providing adequate thickness and thereby not interfering with the strength of the base of the bone anchoring component.

Documents:

707-che-2003-abstract.pdf

707-che-2003-claims duplicate.pdf

707-che-2003-claims original.pdf

707-che-2003-correspondnece-others.pdf

707-che-2003-correspondnece-po.pdf

707-che-2003-description(complete) duplicate.pdf

707-che-2003-description(complete) original.pdf

707-che-2003-drawings.pdf

707-che-2003-form 1.pdf

707-che-2003-form 3.pdf

707-che-2003-other documents.pdf