The treatment algorithms for femoral neck fractures in elderly keep changing constantly and are still controversial because of increasing stress on improving the quality of life in elderly population and associated osteoporosis. Orthopedic surgeons have almost agreed to the advantages of arthroplasty over fixation in improving the outcome in elderly population, but differences still persist as to type of arthroplasty. Options include unipolar, bipolar or total hip arthroplasty. The objective of present study is to compare the outcome of bipolar and total hip arthroplasty in fracture neck femur in Indian elderly population.

A retrospective analysis was performed for comparing the quality of life index in 60 patients over the age of 55 years who underwent bipolar hemiarthroplasty (30 patients) or total hip arthroplasty (30 patients). The follow up period ranged from 3 months to 3 years. Patients were interviewed by an independent observer by questionnaires based on Harris Hip score and Hospital for special surgery score and were examined clinically. The results were analyzed using unpaired t-test.

Though the average period of stay for total hip arthroplasty group was significantly longer but it did not affect the quality of life after 3 months. Patients undergoing total hip replacement were found to be doing significantly better with regards to muscle power, range of motion and function as assessed by unpaired t-test (p < 0.05), but no statistical significant differences were found as far as pain and walking scores were concerned.

Total hip replacement provides a better quality of life to elderly patient with femoral neck fractures compared with bipolar hemiarthroplasty in Indian population.

Bipolar hip arthroplasty was introduced to alleviate the problems of hip pain, acetabular protrusion and femoral stem loosening associated with unipolar prosthesis. Earlier generation bipolar endoprosthesis used to cause varus fixation of outer head which led to the unacceptably high incidence of dislocation, component disassembly and fractures of the polyethylene bearing insert. Second generation endoprosthesis with a self centering mechanism were introduced to overcome these problems. This new design incorporates a polar offset by setting the center of rotation of the inner head proximal to the center of rotation of the outer head, which generates a valgus producing moment at the outer cup. There is a controversy whether this mechanism works in vivo, more so in indigenous prosthesis.

A retrospective observational study was done on 37 subjects, which included 21 males and 16 females. The first radiograph was taken with the patient standing and bearing full weight over the endoprosthetic leg and abducting the contra lateral limb as much as possible. The second radiograph was taken with the patient standing neutral and bearing weight on both the legs. Abduction and adduction views were then taken in supine position. The radiographs were analyzed using the method similar to that of Drinker and Murray. The adductive motion from abduction to neutral position is within the range of inner bearing oscillation. Modified Harris Hip Score was used to evaluate the patients clinically. Results were analyzed using Wilcoxon Matched-Pairs Signed-Ranks Test, Students t-test and Karl Pearson correlation statistics.

The mean outer head alignment changed from 42.46 degrees ±13.62 (range 10 to 72 degrees) to 31.93 degrees ± 10.59 (range 8 to 50 degrees) in moving from abduction to neutral position in weight bearing position. The analysis showed that 68.66% of the total motion occurred at the outer bearing in weight bearing position whereas 73.86% of the total motion occurred at the outer bearing in supine position. The difference between distribution of motion between supine and weight bearing position was not found to be statistically different using Wilcoxon Matched-Pairs Signed-Ranks Test (p = 0.3164) and unpaired students t test (p = 0.35). No correlation was found between weight of the patient and time of follow up with outer head alignment and differential distribution of motion.

Self centering mechanism of bipolar endoprosthesis works in vivo under physiological loads and aligns the cup in neutral or valgus position till an average follow up of 10 months. Though the motion occurs at both the bearing surfaces outer bearing motion clearly predominated in both weight bearing as well as supine position.