Title of Invention

DISTAL FEMORAL PROSTHESIS WITH PIVOTAL HINGE MECHANISM

Abstract

An surgically implantable knee joint called the Distal Femoral Prosthesis with pivotal hinge mechanism consisting of a femoral shaft which has a tapered inter-medullary stem on one end which is cemented to the leftover segment of the femoral bone while the other end has a hollow threaded shaft which mates with the threaded portion of the condylar component, which resembles the condylar section of the femoral bone. The median component mates with the condylar component with two collared bushes and a pivot pin and a pivot pin lock screw. The plateau formed on the dorsal side of the condylar .component acts as stopper at the zero flexion, the assembly so formed give a flexion required and is known as the pivotal hinge mechanism. A tibial anchoring component having a tapered stem with radial grooves running longitudinally across its length is fastened to knurled face of the median component. The median component along with the femoral component tilts side ways depending on the left or right configuration of the limb.

Full Text

I. Field of invention This invention in general related to the fields of medical technology. Further, this invention relates to a novel custom-built endo-prosthesis namely the Distal Femoral prosthesis. More particularly this invention relates to custom-built endo-prosthesis Distal Femoral Prosthesis with Pivotal Hinge Mechanism. II. 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 primary malignant tumors of musculoskeletal system would 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 Tumors, the treatment curettage with 40-60% recurrence rate, Patients with Painful Metastatic lesions were managed palliatively, until they were mercifully relived by death. III. Prior Art Technique and Practice The following description explains in detail the prior art practice, convention, method and technology known in the art. The following description gives in detail the various shortcomings known in the existing state of art. This invention offers a unique solution to surmount the problem associated with the prior art. a. Era of Amputations Amputations were considered to be absolutely necessary for durable local control of the tumor. It was even believed that this kind of ablation should include the entire totality of the effected bone, i.e., for a lesion of the Proximal Tibia, disarticulation through the knee joint was advocated to include the skip lesions also. These radical mutilating cancer clearance surgeries led to marked disability and disfigurement. Amputations is the most merciful of surgeries when it the only resort but the meanest of surgeries when better alternatives are available. Amputations not only remove a physical part of the human body but also a part of the personality of the patient. In order or overcome functional, physiological and social problems associated with amputations, the concept of Limb Salvage was evolved. b. Limb Salvage The aim of Limb Salvage in bone tumor management is to eradicate the disease, retain the integrity of the skeletal and preserve the limb with useful functions using metallic prosthesis known as Endo-prosthesis. The term Custom Prosthesis was designed by us to meet the anatomical and functional demands after excision of bone tumors. This terminology was later christened as Custom Mega-prosthesis by us and we have been using this term 'Custom Mega Prosthesis' as our Trade Mark. c. Endo-prosthesis & Custom Mega prosthesis ™ Endo-prostheses are defined as special segmental bone and joint prosthesis which bridge large defects of the bone. The term Endo-prosthesis was first used in The International Workshop on Design & Application of Tumor Prosthesis, held in Mayo Clinic in 1981. Now-a-days, endo-prosthesis are available for all major anatomic regions of the body i.e., scapula, shoulder joint, Proximal Humerus, elbow, portions of the pelvis, hip joint and proximal femur and also proximal tibia. In addition, total replacements of the femur as well as of the humerus including that of the adjacent joints are feasible. d. Related patents filed by us Patents Awarded Weight Bearing Polymer Pad Mechanism. (ii) PATENT No. 198872 for Proximal Tibial Prosthesis. (iii) PATENT No. 196333 for Distal Femoral Prosthesis with Rotating Hinge Mechanism. (iv) PATENT No. 202044 for Distal Radial Prosthesis with Wrist Joint. (v) PATENT No. 201520 for the Distal Tibial Prosthesis with Ankle Joint Patents Pending 1. Distal Humeral Prosthesis with Elbow Joint (1240/CHE/2004) and Oscillating Mechanism. 2. Proximal Ulnar Prosthesis with Elbow Joint. (1369/CHE/2004) Endo-prosthesis's are available as custom-made prosthesis and as modular systems. Custom made prosthesis's are individually manufactured for each patient and therefore gives an accurate fit. The Distal Femoral Prosthesis discussed here is basically a Cemented Fixation Device. It permits a maximum flexion of 150 degrees before implantation with a normal valgus position of 4-12 degrees in the femoral component. The prosthesis is so designed so as to have the pivotal axis of the prosthesis in the physiological axis of the bone. This is the basic model of all later versions and verities of Custom Mega Prosthesis, which have more features incorporated into them. Patent No. 196333, which has already been awarded, is a Distal Femoral Prosthesis With Thrust Bearing Pad And Rotating Axis Mechanism has been built on this patent Application i.e., Patent No. 898/MAS/2001, with incorporations like Rotating Hinge Mechanism, Thrust Pad Mechanism, etc. Our Patent No. 198872, which has already been awarded, is a Proximal Tibial Prosthesis with a Pivotal Hinge Mechanism. Our Patent No, 198869, which has already been awarded, is a Proximal Tibial Prosthesis with Trust Bearing Pad Mechanism. Our application No: 898/MAS/2001, is a Distal Femoral Prosthesis with Pivotal Hinge Mechanism and our Patent No. 196333, which has already been awarded, is a Distal Femoral Prosthesis With Thrust Bearing Pad And Rotating Axis Mechanism. Even though all these patent applications are for prostheses around the knee joint, the anatomical part replaced by Patent Nos, : Patent No. 198872 and Patent No. 198869 are the Knee and below knee joint of the leg bone (Proximal Tibia ), whereas the patent Application No: 898/MAS/2001, and Patent No: 196333 replace the thigh bone and the knee (Distal Femur). Our other similar Patents that has been awarded are the Distal Radial Prosthesis with Wrist - Patent No. 202044 and the Distal Tibial Prosthesis with Ankle Joint - Patent No. 201520, while our co-pending applications that have been filed is Patent No. 1023/CHE/2003 for the Distal Humerus and Elbow Joint Prosthesis with Oscillating Mechanism and Patent Application No. 1369/CHE/2004 for Proximal Ulnar Prosthesis with Elbow Joint are designed to replace the elbow joint with a portion of Humerus and Ulna respectively. IV. Objects of Invention It is primary object of the invention to invent design and construct a novel -Distal Femoral Prosthesis with Knee Joint. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis - Distal Femur, which is unique. It is yet another object of the invention to invent, design and construct a novel prosthesis, which mimics the physiological action of the distal part of the femoral bone. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis - 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, design and construct a novel-distal femoral prosthesis which would take care of the structural loading which has to be encountered by the distal part of the femoral bone before the lesions. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis -distal femur, which would avoid disfigurement of knee and the femoral bone. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis-distal femur, which would avoid disfigurement of knee and the distal part of the femoral bone. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis-distal femur, which would preserve the distal part of the femoral bone. It is yet another of the invention to invent, design and construct a novel endo-prosthesis-distal femur, which matches in profile the anatomic region of the distal femur. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis- distal femur, which is economical. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis-distal femur, which is safe in usage. It is yet another object of the invention to invent, design and construct a novel endo-prosthesis - 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 design and construct a novel, wherein the femoral stem tilts sideways by an angle ranging between 6-12 degrees to the left when viewed from the lateral side for a RIGHT configured distal femur prosthesis. It is yet another object of the invention to invent design and construct a novel, wherein the femoral shaft tilts sideways by an angle ranging between 6-12 degrees to the right when viewed from the lateral side for LEFT configured distal femur. Further the objects of the invention will be clear from the following description. Preferred Embodiment of Invention The following pages will describes in detail with reference drawings accompanying the specifications. The nature of the invention and the manner in which it is to be performed is clearly and sufficiently described in the complete specifications. The final portion of the complete specifications ends with a statement of claims, which defines the invention. Fig -1 shows iso-metric view of Distal Femoral Prosthesis in Un-Flexed Position Fig-2 shows elevation and side view of a Right Configured Prosthesis. Fig-3 shows exploded view of the distal femoral prosthesis, Fig-4 shows elevation and side view of a Left Configured Prosthesis Fig-5 shows iso-metric view of the Femoral head. Fig- 6 shows sectional view of the Femoral Head. Fig-7 shows an iso-metric view of the Tibial Sub assembly Fig-8 show sectional Elevation of the prosthesis. Fig- 9 shows sectional Side view of the prosthesis. Fig -10 shows the elevation of the prosthesis in Flexed Position, Description Distal Femoral Prosthesis comprises of four major components. Basic components of the device are designated by numeral in the illustrated drawings and are referred in the description of the complete specification. The designations of various parts of the device (Figure 3 in the Drawing Sheet) are as follows: a. Femoral Shaft (1) b. Condylar component (3) c. Median Component (6) d. Tibial Intermedullary Stem (7) e. Pivot Pin (4) f. Collared Bushes (5) g. Lock Screw (2) and h. Pivot Lock Screw (8) The detailed description of important parts referred herein is as follows, a. Femoral shaft (1) also known as the femoral stem mates with the condylar component on one end (3); and forms the bone anchoring component on the other (b). The femoral shaft end that forms the bone anchoring (b), is a tapered stem with longitudinal grooves (a) on its surface numbering 3 to 6, running transversely over its length forming the Femoral Anchoring Component also known as the intramedullary stem. The other end (c) evolves into a cylindrical shaft known as femoral component. The shaft has a threaded bore (d) on its base which mates with the male threaded stud (f) on the Condylar Component (3). b. Condylar Component (3) (Ref. Drawing 3, 5 & 7) is fastened to the femoral shaft (2) on end (i.e., f mates d) and on its other end with the median component (6), Pivot Pin (4) and Bushes (5) to form the pivotal hinge mechanism. The feature that mates with the femoral shaft is a threaded stem (f), as in Fig-(3 & 7). This threaded stem tilts sideways depending on its configuration, i.e., the femoral stem tilts sideways by an angle ranging between 6-12 degrees to the left when viewed from the dorsal side for a RIGHT configured distal femoral prosthesis Fig-2. For a LEFT configured distal femur, the femoral shaft tilts sideways by an angle ranging up to 15 degrees to the right when viewed from the lateral side Fig-4. The condylar component has two hub like features ( The rib (oo) on the Condylar component has a threaded hole (a), that serves to lock the pivot pin (4) in position. The Pivot Pin (4) is locked in threaded hole P (on one of the hubs (8) with its axis parallel to that of the axis A-3, and Perpendicular to that of the axis of the prosthesis A-2, serves to house the lock screw (2). b. Median Component links the condylar component (3) on one end and the tibial Stem (7) is fastened the other. The upper part of this median component has a horizontal bore (m) on to which two collared bushes (5) of a bio-compatible polymer rotate. The ribs (© & 8) of the condylar component aligns with the horizontal bore and held in position by a pivot pin (4) and lock screw (8). The lower face (p) (as in Fig. 3) of the median component has a threaded blind hole (q), The axis of which A-l, aligns with the axis of the prosthesis. This face also has serration's on its lower side (p), which are either diamond or rectangular in profile. c. Tibial Component also known as the tibial anchoring component is fastened to the median component, vide threaded hole (q) on the median component. It is a tapered stem with longitudinal grooves (t) on its surface numbering 3 to 6, running transversely over its length forming the tibial anchoring component also known as the intramedullary stem. The other end (r) evolves into a threaded shank which mates with the Median Component. The feature abutting these two (s), is either hexagonal, pentagonal or square in cross-section. This is to facilitate the fastening of the tibial component to the median component. Pivotal Hinge Mechanism The basic function of the Pivotal Hinge Mechanism is to impart flexion of 150 degrees between the femoral component and the Tibial component on the dorsal side with the pivotal pin as the fulcrum. The components which form part of the Pivotal Hinge Mechanism are (3) Median Component, (4) Pivot Pin, (5) Collared Bushes and (8) Lock Screw. The Pivotal Hinge Mechanism is as shown in Fig- 3, 5, & 7. Two collared sleeves (5), made of a bio-compatible polymer slide into the horizontal bore (h), of the median component, with the inner side of the collars (o), butting the two faces of the median component. The two flanges (oo & 8 ) rising on either side on the dorsal side of the condylar component and has a drilled hole on each flange which are concentric to each other and is aligned to Axis A-3 as in Figure 1 2. One of the flanges (a) has a threaded bore ((p), and the other a plain drilled hole (P). The pivot pin (4) is threaded on one end (k) and has a collar (j) and a cylindrical head with a radial slot on the other end. The middle part of the pivot pin is designed to give a rotating fit with the bushes and the median component. The pivot pin is fastened into the bore (p), the bushes (5), and then into the threaded bore (cp). The lock screw (8) is positioned into the threaded hole (a), prevents the axial motion of the pin thereby locking the whole pivot mechanism. The median component (6) along with the bushes (5), are fixed in between the two flanges (8 & Ti) as in Fig. 5, on the dorsal side of the condylar component and are aligned with the axis of the holes A-3, on the median component. The pivot pin (4) mates into this system with the threaded end with the threaded hole and the head side with the plain hole forming the pivotal hinge mechanism. The lock screw enters the condylar component through a tapped hole (o) on one of its flanges. The lock screw has a cylindrical tip on one end and a radial slot on the other end and threaded all through its body. The cylindrical tip of the lock screw seats into collar of the pivot pin thereby locking the axial movement of the pivot pin and consequently the whole pivot mechanism. Fig-8. The axis of the condylar component and the tibial component, in its un-flexed position (Unfolded) is at 180 Degrees to each other as in Fig-4. This position is taken as the zero flexion position. At this zero flexion position the face (n) of the median component as in fig-3 butts with the face (a) of the condylar component (Fig. 6). This face (a) as in Fig. 5, which is adjoining the radial groove (a) on the dorsal side of the condylar component acts as a stopper at this point, i.e., there will be no further flexion beyond this point on the ventral side. Taking the above position as the zero flexion point the prosthesis will take a flexion of up to 150 Degrees on the dorsal side limited till the face (n) of the median component butts the face (u) of the condylar component about the axis of the pivot pin and hence named as the pivot pin mechanism- The femoral shaft attached to the condylar component is tilted sideways depending on the orientation of the prosthesis, i.e., left or right configuration. This is achieved by tilting the threaded stem (f), on the condylar component to the desired angle during manufacture. For the RIGHT femoral configuration (Fig-2) the femoral shaft tilts towards the left by a degree ranging between 6-12 degree when viewed from the lateral side. This is achieved by means of a inclined threaded stem (f) on the condylar component as in Fig-5. The threaded hole (d), on the lower part of the femoral shaft mates with the tapped stem of the condylar component thus producing the desired inclination. For a Left configured prosthesis this threaded stem (ii), tilts to the right when viewed from the lateral side as in Fig-4. It is to be noted that the complete specification discloses salient features of the invention. Within the scope of the invention, various modifications and combinations are possible. The scope and ambit of the invention is defined in the following statement of claims. We Claim 1. An surgically implantable knee joint christened as the Distal Femoral Prosthesis with pivotal hinge mechanism, the invention characterized herein consists of a femoral shaft which has a tapered inter-medullary stem on one end which is cemented to the leftover segment of the femoral bone while the other end has a hollow threaded shaft which mates with the threaded portion of the condylar component and which resembles the condylar section of the femoral bone, while the axial bore of the median component mates with two holes on the hub which is formed by two raised walls on the dorsal side of the condylar component along with two collared bushes and a pivot pin and is locked with a pivot pin lock screw whose nose tip buts with the cavity formed by the collar on the pivot pin, the plateau formed on the dorsal side of the condylar component acts as stopper at the zero flexion, the assembly so formed give a flexion of a semi constrained uniaxial rotating mechanism known as the pivotal hinge mechanism, which mimics the functions and physical profile of the human knee joint, a tibial anchoring component which has a tapered stem with radial grooves running longitudinally across its length while the other end with a threaded shaft is fastened into the threaded hole on the knurled face of the median component, the median component along with the femoral component tilts side ways depending on the left or right configuration of the limb. 2. Distal Femoral Prosthesis with pivotal hinge mechanism as in claim 1, wherein the condylar component has physical and functional features resembling the profile of the condylar region of the femoral bone. 3. Distal Femoral Prosthesis with pivotal hinge mechanism as in claim 1, wherein the median component mates with the holes on the raised walls on the dorsal side of the condylar cavity on the condylar component with collared bushes, pivot pin and lock screw to form a Pivotal Hinge Mechanism. 4. Distal Femoral Prosthesis with pivotal hinge mechanism as in claim3, wherein the said bushes act as journal bearing to minimize the impact of wear and to give the joint a frictionless flexion. 5. Distal Femoral Prosthesis with pivotal hinge mechanism as in claim 3, erein the two collared bushes makes a rotating fit with the bore on the median with their collar face butting the outer face of the median component. 6. Distal Femoral Prosthesis with pivotal hinge mechanism as in claim 1, wherein the nose of the lock screw butts the cavity formed by the collar in the pivot pin thus ensuring a positive locking. 7. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 1, wherein the plateau formed on the upper tangential face of the radial groove on the dorsal side of the condylar component acts as a stopper in the zero flexion position by butting with the median component. 8. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 1, wherein the plateau formed on 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 inner face of the median component. 9. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 1, wherein the tibial anchoring component is mounted on the lower knurled face of the median component by a threaded joint. 10. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 1, wherein the femoral shaft along with the median component tilts sideways by a small degree. 11. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 10, wherein the femoral shaft tilts to the left, when viewed on the front elevation, for the right limb configuration. 12. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 10, wherein the femoral shaft tilts to the right, when viewed on the front elevation for the left limb configuration. 13. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 1, wherein the radial groove on the ventral side of the condylar component is concentric to the axis of the pivotal holes. 14. Distal Femoral Prosthesis with pivotal joint mechanism as in claim 1, wherein the tibial anchoring component has a hexagonal or a square cross-section butting the threaded region followed by a tapered section with a few longitudinal groove running longitudinally across its length. 15. Distal Femoral Prosthesis with pivotal joint mechanism as in claimed in Claim 1 and in the complete specification and as illustrated by way of drawings accompanying the complete specification as a whole assembly to be used to supplement of the knee joint including the distal portion of the femoral bone.

Documents:

898-mas-2001-abstract.pdf

898-mas-2001-claims duplicate.pdf

898-mas-2001-claims original.pdf

898-mas-2001-correspondence others.pdf

898-mas-2001-correspondence po.pdf

898-mas-2001-description complete duplicate.pdf

898-mas-2001-description complete original.pdf

898-mas-2001-drawings.pdf

898-mas-2001-form 1.pdf

898-mas-2001-form 19.pdf

898-mas-2001-form 3.pdf