Abstract
Aims: To determine which radiological features were most significant in aseptic loosening (AL) of Charnley total hip replacement (THR) and to compare the prevalence of these features between a specialist hip surgeon and those from the general setting. Method: An analysis was performed of the initial post-operative radiographs of three groups of Charnley femoral stems: I: Failed stems within 5 years due to AL, as registered in the Trent Regional Arthroplasty Study (TRAS). II: 44 consecutive Charnley THRs performed by a single, ‘specialist’ hip surgeon. III Controls: A randomly selected cohort group from the TRAS (proven to be clinically and radiologically intact at 5 years). Results: The most significant radiographic features of failure were: (i) mantle width < 2mm in any zone giving an odds ratio of 21.0 for failure (CI 3.3 to∞; p< 0.05); (ii) “inadequate” cementation grade (Barrack grades C and D) giving an odds ratio of 9.5 for failure (CI 3.2 to 28; p< 0.05). The specialist hip surgeon achieved a significantly higher proportion (79.5%) of complete cement mantles (> 2mm) than the controls (50%) (Chi^2 = 9.455, df = 1, p=0.002). There were also a higher proportion of adequate cementation grades (88.6% vs 82%) although this difference was not significant (Chi^2= 0.947, df = 1, p=0.330). Conclusion: We have demonstrated features identified on radiographs of Charnley femoral stems predictive of failure. In our study a specialist hip surgeon achieved fewer flaws than those detected across a regional ‘average’. This suggests surgical technique can influence radiological results and thus outcome. This needs to be emphasized, particularly during training, in the hope of improving overall results in the future. However, even a specialist’s cementation appeared inadequate in 11.4% of cases, suggesting that factors outside the surgeon’s control, influence cement grading. This is important from a medico-legal standpoint because surgeons are being criticised for not achieving adequate cementation in negligence cases.
These abstracts were prepared by Mr Peter Kay. Correspondence should be addressed to him at The Hip Centre, Wrightington Hospital, Appley Bridge, Wigan, Lancashire WN6 9EP.
