Critical radiological analysis after Austin Moore hemiarthroplasty

The aim of this study is to investigate the causes of prosthesis loosening in patients treated with Austin Moore hemiarthroplasty (AMA). The clinical and radiological outcomes were documented in a quantitative manner after 7 years follow-up of 144 patients. At the time of final follow-up, 52 patients had died and 48 patients were lost to follow-up, leaving a total of 44 patients for analysis. Immediate post-operative X-rays were studied for the initial alignment of prosthesis, the fit of the prosthesis and the degree of osteoporosis. X-rays on latest follow-up were studied for evidence of loosening. All patients were assessed clinically with the hip score of hospital for special surgery. It was found that hip pain was significantly related to subsidence and pivoting of the prosthesis (P = 0.014 and 0.035, respectively). Significant increase in subsidence was noted if the stem of prosthesis was not fitting well within the shaft of femur (P = 0.006). When the patient was younger than 73 years old at the time of operation, there was more subsidence of the prosthesis at the final follow-up (P = 0.001). It was concluded that the fill of AMA within the shaft of femur should be greater than 70% to avoid early loosening. Relatively younger patients with acute fracture of the neck of femur should be treated by methods other than cementless AMA.