|Title of Invention||
PROXIMAL TIBIAL PROSTHESIS
|Abstract||ABSTRACT The proximal tibial prosthesis with knee Joint comprises the following parts, a femoral anchoring component which forms the bone anchoring component on one end and has a threaded shank at the other end that mates with the median component. The median component links with the tibial head on the other end by means of a horizontal bore that aligns with the hub of the tibial head and is held in position by a pivot pin. The median component linking the femoral component and the tibial head forms the pivot hinge mechanism, which permit a flexion of 150 degrees. The tibial head component ends in a male threaded stem which mates with the threaded hole in the tibial slim. The tibial head and stem substitute the proximal part of the tibial bone that is removed.|
|Full Text||This invention retakes to proximal tibial prosthesis.
This invention in general relates to the field of medical technology. Further, this invention relates to a novel custom-built endoprosthesis Proximal tibia. More particularly this invention relates to custom-built prosthesis - Proximal Tibia.
Management of patients with musculoskeletal neoplasms has always been one of the most cheapening areas in oncology. Prior to 1970, almost every patient with primary malignant tumours 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 palliative 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 tumours only and saving the limb of the patient was developed. The aim of limb salvage in bone tumours 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 endoprosthesis replacement revolutionized limb salvage by providing a method of reconstruction that provides stability and mobility. The endoprosthesis 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 endoprosthesis needs to be fabricated according to the anatomical dimensions of the patient and is therefore termed as the Custom Prosthesis.
The 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: 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 condoler component the other end, which mates with the median component, forming the pivot joint mechanism. The median component forms the pivotal hinge at its upper end and the lower end, anchors to the tibial bone by means
outlet£ tibial manicuring component. The pivotal hinge mechanism is formed between the condoler 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. It has 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°.
This patent application No: 897/MAS/200l, 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 medial 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 design 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. It differs from the patent application No: 898/MAS/200I because of the anatomical region of the skeleton replaced which is distal femur in application No: 898/MAS/2001 and proximal tibia in application No: 897/MAS/200I. Due to this fact, there are several differentiating features between these two patent applications. The differentiating features between patent application No: 1002/MAS/2002 and application No: 897/MAS/200I, are the provision of the polygonal weight bearing pad which is fixed to the lower aspect of the median component in application No: 1002/M AS/2002. The under surface of this pad has two semi circular contoured cavities to accommodate the tibial head. This polymer pad is absent in application No: 897/MAS/2001. In application No: 897/MAS/2001, the lower end of the condoler component evolves into a threaded stem which mates with a threaded hole in the upper part of the tibial component, whereas in application No: 1002/MAS/2002 the lower part of the condoler component evolves into a distal extension which fits into a hollow cavity the upper end of the tibial intramedullary stem by means of two screws.
Objects of invention:
The Objects of the invention was to invent, create and construct a novel
proximal tibial prosthesis. Which should be unique with knee Joint?
Which would mimic the physiological function of the proximal tibial bone Which retains the functional aspects of the proximal tibial bone along with the
knee joint. Which takes care of the structural loading of proximal tibia after resection? Which would avoid disfigurement of knee and proximal tibial bone Which would preserve the proximal part of tibia Which matches the anatomic region of the proximal tibia Which is economical Which is safe in usage Which should have the femoral stem till sideways by an angle of 6° to the left
when viewed from the frontal side for a RIGHT tibial configuration. Which should have the femoral stem th sideways by an angle of 6° to the
right when viewed from the frontal side for a LEFT tibial configuration.
Further the objects of the invention wilt are clear from the following description of parts.
Proximal Tibial prosthesis comprises of the following components,
1. Femoral Components Fig 2, 7 & 8
2. Medial Component Fig.2, 7 and 8
3. The collared bushes Fig 2 and 7
4. Pivot locking screw Fig 2 and 9
5. Tibial Head (Condoler component) Fig,2, 5,6 and 8
6. Pivot pin Fig 2 and 9
7. Tibial stem Fig 2,8 and 9
8. Locking screw (Tibia)) Fig.2.
Preferred Embodiment of Invention
The following pages will describe in detail with reference drawings accompanying the complete specification. 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 specification ends with a statement of claims, which defines the scope invention. Further details regarding the invention are illustrated by way of accompanying drawings, in which.
Fig. 1 shows isometric view of Proximal Tibial Prosthesis Fig. 2 Shows exploded view of Proximal Tibial Prosthesis Fig. 3 shows elevation and Side View of Proximal Tibial Prosthesis - Right
configuration. Fig. 4 shows elevation and Side View of Proximal Tibial Prosthesis - Left
configuration. Fig. 5 shows detail view of condoler region of Tibial Head Fig. 6 shows sectional view of the Tibial Head Fig. 7 shows is-metric view of the sub-assembly on the femoral side Fig. 8 shows elevation of the prosthesis in fully flexed position Fig. 9 shows sectional Elevation of the Prosthesis Fig. 10 shows sectional Side view of the Prosthesis.
Basic components of the device are designated by numeral in the illustrated drawings and are referred in the body of the complete specification.
a). Femoral Component also known as the femoral anchoring component (1) mates with the median component (2) on one end with (d) mating with hole (Q, and forms the bone anchoring component on the other (b). The end that forms the bone anchoring (b) is a tapered stem with longitudinal grooves (a) on its surface numbering 3 to 4, running transversely over its length forming the Femoral Anchoring Component also known as the intramedullary stem. The other end (d) evolves into a threaded shank which mates with the Median Component. The feature
abutting this ivy-o (c) is hexagonal, pentagonal or square in cross section. This is to facilitate the fastening of the femoral component to the median component.
b) Median Component links the femoral component (1) on one end and the
condoler component (5) on the other end forming the Pivotal Hinge Mechanism. The
lower part of this median component has a horizontal bore (h) on to which two
collared bushes (3) of a bio compatible polymer rotate, The hub (y & Z) (Fig .5) of
the tibial component aligns with the horizontal bore (h) and is held in position by a
pivot pin (6) and lock screw (4).
The upper face (e, Fig.7) of the median component has a threaded hole (0 whose axis (A-i), tilts sideways depending on whether the configuration is left or right tibial prosthesis, when viewed from the lateral side.
For the Right tibial configuration the femoral component tilts to the left side as in Fig.3, and for the left tibial configuration it tilts to its right when viewed from the anterior position, as in Fig.4.
c) Tibial Head and Stem sub assembly comprises of the Tibial Head (Condoler
Component) (5), Tibial Stem (7) and the lock screw (8). It Is the sub assembly that
substitutes the proximal part of the Tibial bone that is to be salvaged; Its condoler
region (j) resembles that of the proximal part of the tibia itself The condoler region
of the tibial Head in Fig.5, has two hub (y & z) like features on the dorsal side which
mates with the median component as in Fig-5. One hub (z) has a threaded hole and
the other a plain hole (y), both on the same axis A-3, that is perpendicular to the axis
(A-]) of the prosthesis.
This condoler region (5, Fig,2) then smoothly evolves into a male threaded stem (i|/) which mates with the threaded hole (B) in the Tibial stem (7) This tibial stem (p) which is cylindrical in shape on one end, and on the other end of this stem is the tibial anchoring component which is an intermediary fixation device (q) which is cylindrically tapered with longitudinal grooves on its surface ranging from three to four, running transversely over its length to enhance the fixation.
d). Pivotal Hinge Mechanism the basic function of which, is to impart a flexion of about! 45 as in Fig.8, between the femoral component and the tibial component on the dorsal side. The components which form part of the pivotal hinge mechanism are femoral component (1), Median Component (2), Tibial Component (5), Pivot Pin (6), and Collared Bushes (3) and lock screw (4).
The pivotal hinge mechanism is as shown in Fig.2,9 & 10 Two collared bushes (3), made of a bio compatible polymer slide into the horizontal bore (h) of the median component, with the inner side of the collars (g), butting the two faces of the median component (r). Fig, 2 & 7.
The two flanges (q & v Fig.5) rising on either side on the dorsal side of the tibial component in the condoler have a reamed hole on each flange, one threaded (z) and the other a plain-reamed hole (y) as in Fig.5.
The pivot pin (6 Fig. 2 »& 9) is threaded on one end (m) and has a collar (k) and a cylindrical head (1) with a radial slot on the other end. The middle part of the pivot pin (n), is designed to give a rotating fit in association with these bushes and the
median component. The collar (k) in conjunction with the lock screw (4) prevents the axial motion of the pivot pin thereby locking the whole pivot mechanism (Fig. 9 & Fig. 10) in the assembly unit.
The median component along with the bushes are fixed in between the two flanges (q & v, Fig 5 ) on the dorsal side of the tibial component and arc aligned with the axis of the holes on the tibial component. The pivot pin (6) mates into this system with the threaded end (m) with the threaded whole (z) and the head side (1) with the plain whole (y) forming the pivotal hinge mechanism.
The lock screw enters the tibial component through a tapped whole (I, Fig.5) on one of the flanges (y) of the tibial component. The lock screw has a cylindrical tip on one end and a radial slot on the other end, threaded through its body. The cylindrical tip of the lock screw seats into collar (k. Fig.2) of the pivot pin thereby locking the axial movements of the pivot pin and consequently the whole pivot mechanism. Fig.8.
IHCl axis of the tibial component and the femoral component in its inflexed position (unfolded) is at 180 to each other as in Fig-3&4. This position is taken as the zero flexion position.
At this zero flexion position the face (i) of the median component as in fig.5 & 8, butts with the face (s) of the condoler component. This face (s) which is adjoining the radial groove ( r) on the dorsal side of the tibial component acts as a stopper at this point, i.e., there wilt 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 145** on the dorsal side limited till the face (i) (f1g-2) of the median component butts the face (x) (fig.5) of the tibial component about the axis of the pivot pin and hence named as the pivot pin mechanism.(fig.8)
The femoral component attached to the median component is tilted sideways depending on the orientation of the prosthesis, i.e. left or right tibia. For the RIGHT Tibial configuration (Fig, 3) the femoral component tilts towards the left by 6". This is achieved by means of the inclined lapped whole (f) on face (2e) in the median component as in Fig. 2, 7&9. The ma\e threaded shank (d), on the lower pan of the femoral component mates with the tapped whole (f). of the median component, thus producing the desired inclination.
It is to be noted that the complete specification discloses salient features of the invention. Within the scope of the invention various modifications are possible. The scope and ambit of the invention is defined-in the following statement of claims.
1. Proximal Tibial prosthesis having pivotal hinge mechanism comprising of a femoral component, a median component, a tibial head and stem sub assembly, a pivot pin with lock screw and two collared bushes, the said components being integrated to form a device, consisting of a pivotal hinge mechanism wherein femoral anchoring component mates wily the median component on one end with mating wily hole and forms the bone anchoring component on the other, the median component links the femoral component on one end and the Tibial Head on the other end forming the Pivotal Hinge Mechanism , the Tibial Head and Stem sub assembly comprising the Tibial Head, Tibial Stem and the lock screw, the said sub assembly replaces the proximal part of the Tibial bone that is to be salvaged, the basic function of the Pivotal Hinge Mechanism being to impart a flexion of about 145 between the femoral component and the Tibial component on the dorsal side.
2. Proximal Tibial prosthesis with pivotal hinge mechanism as in claim 1, wherein the Tibial component has a solid stem, with the condoler region's profile resembling the of the proximal region of the tibial bone itself.
3. Proximal Tibial prosthesis with pivotal hinge mechanism as in claim 1, wherein the pivotal joint mechanism of the median component being fitted to the proximal part of the tibial component with collared bushes, pivot pin and lock screw.
4. Proximal tibial prosthesis with pivotal hinge 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. Proximal Tibial prosthesis with pivotal hinge mechanism as in claim 3, wherein the orientation of the collared bushes with respect to the median and that tibial components.
6. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 3, wherein the bottom tip of the lock screw butting the collar in the pivot pin thus ensuring a positive locking.
7. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 3, wherein the upper tangential face of the radial groove on the dorsal side of the tibial component acts as a stopper in the zero flexion position by butting with the median component.
8. Proximal Tibial prosthesis with pivotal joint mechanism as, in claim 3, wherein the lower tangential face of the radial groove on the dorsal side of the tibial component acting as a stopper in full flexion position by butting with the median component.
9. Proximal Tibial prosthesis with pivotal joint mechanism as in claim I, wherein the femoral anchoring component is mounted on the upper face of the median component by a threaded joint.
!0. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 9, wherein the
femoral anchoring component tilts sideways by about 3 to 14 degrees. H. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 10, wherein
the femoral anchoring component tilts to the left, if viewed from the lateral
position for the right limb configuration. 12. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 10, wherein
the femoral anchoring component tilts to the right, if viewed from the lateral
position for the level limb configuration.
13. Proximal Tibial prosthesis wily pivotal joint mechanism as in claim 1, where in the radial groove on the ventral side of the dorsal region of the tibia! component is concentric to the pivotal holes,
14. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 13, wherein the radius of the radial groove on the ventral side of the tibial component ranges from 10lo25 Millimeters.
15. Proximal Tibial prosthesis with pivotal joint mechanism as in claim 1, wherein the femoral anchoring component has a hexagonal or a square cross-section butting the threaded region followed by a tapered section with longitudinal groves ranging from 3 to 6 in numbers.
16. Proximal Tibial prosthesis with pivotal joint mechanism as in claim I, wherein the
extreme tips of the femoral component and the tibial components are tangentially
round in section.
|Indian Patent Application Number||897/MAS/2001|
|PG Journal Number||08/2007|
|Date of Filing||02-Nov-2001|
|Name of Patentee||PROF. MAYIL VAHANAN NATARAJAN|
|Applicant Address||NO.4, LAKSHMI STREET, KILPAUK, CHENNAI 600 010|
|PCT International Classification Number||A61F2/02|
|PCT International Application Number||N/A|
|PCT International Filing date|