Abstract
Abstract
Introduction
Bipolar hemiarthroplasty(BPHA) for displaced intracapsular neck of femur fractures(DICNOF) is a controversial topic as conflicting evidence exists. The most common reason for revision to total hip arthroplasty(THA) from BPHA is acetabular erosion. In our study, we sought to quantify the direction of migration of the bipolar head within the first 3 years post-operatively.
Methods
A proportional index in the horizontal and vertical planes of the pelvis were used to quantify migration. This method removed the need to account for magnification and rotation of the radiographs.
Results
There were a total of 35 patients (8males, 27females) included, with an average followup of 2.3years (816days). 7 did not migrate, these were all female. For the remainder, per year of insertion, the average horizontal migration was 0.005769439 and the average vertical migration was 0.004543352, suggesting superomedial movement.
Discussion
BPHA has been shown to provide results similar to those of THA in patients with DICNOF. The main cause of revision to THA is migration thought to be from loss of cartilage volume from mechanical wear, that causes pain. We have quantified this migration as minimal. None of our patients required revision to THA and none sustained dislocation or loosening in this followup period. This would fit with the meta-analyses looking at BPHA, which shows bipolar articulations reduce the amount of wear. We also identified a trend that in the female population migration is less likely to occur. This would add evidence to the theory that mechanical factors are significant in the volumetric wear caused by hemiarthoplasty.
Conclusion
BPHA was found to be safe and effective in our cohort of patients with minimal migration and no need for revision at an average of 2.3years. Our data is concurrent with the literature in theorising that BPHA reduces wear at the prosthesis-cartilage interface.
