We have performed a study comparing the radiological results of Total hip replacements performed by a single, experienced specialist hip surgeon with those reported from the Trent Regional Arthroplasty Study (TRAS) [presented at BOA congress 2000]. Results from TRAS have revealed that inadequate cementation grades and a cement mantle width of < 2mm were the most significant associations predicting early aseptic loosening. Interestingly, their respective incidences were as large as 20% and 50% in a random sample of THRs from the TRAS register.

Data is lacking as to whether poorer radiographic cementation grades have a trend towards individual surgeons or whether they are more evenly distributed amongst the surgical population including those adhering to modem techniques.

Therefore, we have undertaken an independent review of A-P and lateral radiographs of 33 consecutive Charnley THRs performed by a specialist hip surgeon using carefully controlled modem cementing techniques and compared the results with the same random cohort of THRs from the TRAS.

Our results show that the specialist surgeon achieved a significantly higher proportion (82%) of complete cement mantles (> 2mm in all zones) than those achieved by TRAS (50%) [Chi²=7. 79, p=0. 0052]. This suggests that improved cement mantles can be achieved by the adoption of carefully controlled modem cementing techniques. However, use of the Barrack system of grading was unable to detect differences in cementation quality between specialist (88%) and TRAS group (81%) [Chi²=0. 235; p=0. 631 suggesting less sensitivity in this technique for assessing cementation quality. These results are important for the following reasons. Achievement of adequate mantle (> 2mm) can be improved upon by adoption of carefully controlled modem cementing technique. However, regardless of the method of assessment of cementation quality, approximately 18% will appear ‘inadequate’ despite modern techniques suggesting that factors outside the surgeon’s control are involved in determining cementation grade. This has important medico-legal implication in the current climate in which surgeons are being criticised, in negligence cases arising out of the 3M Capital Hip experience, for achieving ‘inadequate’ cementation.

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.

The radiological features of the cement mantle around total hip replacements (THRs) have been used to assess aseptic loosening. In this case-control study we investigated the risk of failure of THR as predictable by a range of such features using data from patients recruited to the Trent Regional Arthroplasty Study (TRAS).

An independent radiological assessment was undertaken on Charnley THRs with aseptic loosening within five years of surgery and on a control group from the TRAS database. Chi-squared tests were used to test the probability of obtaining the observed data by chance, and odds ratios were calculated to estimate the strength of association for different features.

Several features were associated with a clinically important increase (> twofold) in the risk of loosening, which was statistically significant for four features (p < 0.01). Inadequate cementation (Barrack C and D grades) was the most significant feature, with an estimated odds ratio of 9.5 (95% confidence interval 3.2 to 28.4, p < 0.0001) for failure.