Bi-Polar Prothesis-Talwakar Type-Hard Top Non Fenestrated after some time functions as a unipolar device. There is a need to change the design of bipolar hip prostheses to make it function as a bipolar device over a prolonged period of time. A bicentric bipolar hip prosthesis was used as an implant for various conditions of the hip. We evaluated the movement of this newly developed prosthesis at the interprosthetic joint radiologically at periodic intervals.
Materials and Methods:
Fifty two cases were operarted with the Bi-Polar Prothesis-Talwakar Type-Hard Top Non Fenestrated for indications like fracture neck of femur and various other diseases of the hip and were followed up with serial radiographs at periodic intervals to evaluate, what fraction of the total abduction at the hip was occurring at the interprosthetic joint.
In cases of intracapsular fracture neck of femur, the percentage of total abduction occurring at the interprosthetic joint at 3 months follow-up was 33.74% (mean value of all the patients), which fell to 25.66% at 1.5 years. In indications for bipolar hemireplacement other than fracture neck of femur, the percentage of total abduction occurring at the interprosthetic joint at 3 months follow-up was 71.71% (mean value) and at 1.5 years it was 67.52%.
This study shows the relative preservation of inner bearing movement in the bipolar hip prosthesis with time probably due its refined design. Further refinements are needed to make the prosthesis work better in patients of intracapsular fracture neck femur.
All patients in whom this prosthesis was used were divided into the following two groups: Group 1: Fracture neck of femur; Group 2: Non-traumatic hip pathologies that severely hampered the quality of life of the patients due to pain at hip and restriction of mobility. These included healed tuberculosis hip, monoarticular rheumatoid involving the hip joint, ankylosing spondylitis and non-traumatic avasular necrosis (osteonecrosis) of the femoral head with secondary osteoarthrosis involving the hip. Patients who had undergone any surgical intervention (like screw fixation for neck femur fractures, core decompression for osteonecrosis femoral head, etc.) were excluded from the study.
In all cases uncemented type of hip hemireplacement arthroplasty was performed. The post-operative protocol was to encourage the patients to perform quadriceps strengthening exercises from post-operative day 1, and partial weight bearing walking was allowed from 3 days after the operation and full weight bearing was allowed at 6 weeks from the date of operation.
Anteroposterior plain radiographs of both hips were taken with the patient supine in the neutral position, (both in terms of abduction/adduction and rotation,) and then in maximum abduction of the operated limb, maintaining neutral rotation with the non-involved limb still in a neutral position (adduction/abduction and rotation). On the X-ray in the neutral position, a line drawn tangential to the most inferior aspects of the ischia was used as a reference line and angle A was defined by the intersection with this line of a line drawn along the inferior margin of the acetabular component. Angle B was formed by the intersection of the ischial reference line with a line drawn along the center of the long axis of the femoral stem. The exercise was repeated on the anteroposterior radiograph taken with the operated limb in maximum abduction position and angles A1 and B1 were plotted