O2362 THE PREVALENCE OF RE-PRODUCING THE ANATOMIC POSITION IN UNCEMENTED TOTAL HIP REPLACEMENT: DOES IT MATTER?

Abstract

Aims: To establish the frequency of achieving the desired prosthesis position in an uncemented total hip replacement and the effect of the position on outcome. Methods: We reviewed the earliest and most recent available post-operative pelvic x-rays of 96 patients who had undergone a total hip replacement between March 1992 and December 1995. A press þt hydroxyapatite coated cup and stem were used in all cases (CSF & JRI respectively). We assessed the following parameters: Centre of rotation, off set, cup angle, leg length and insert wear. We then established the clinical outcome at 5–9 years of 88 patients using the MDP scoring systems and correlated this with the radiological study to establish the effect of prosthesis placement on the clinical outcome. Results: There was an acceptable centre of rotation in 53.6% of the patients, 44% of the patients had a cup angle of 40–49 degrees, 73% had an adequate off set and 71.7% had equal leg lengths. There was no correlation between the MDP and the centre of rotation, cup angle, off set or leg length. There was also no correlation between these parameters and wear of the liner. Conclusion: It is evident that the desired position of the prosthesis is not achieved in a signiþcant number of patients. This does not seem to correlate with the clinical outcome and wear. Extreme deviation from the anatomical position is likely to be detrimental.