Aim: To compare the difference in periprosthetic bone density between cemented and uncemented total hip replacement at a minimum follow up of 10 years.

Patients and methods: We looked at a cohort of 17 patients who have had bilateral total hip replacement with cemented Charnley total hip on one side and uncemented Furlong total hip on the other side between 1984 and 1994 (minimum follow up 10 years). Harris and Oxford hip scores were used to determine the function, SF 36 was used to measure quality of life and Dual energy X-Ray absorptiometry (DEXA) scan was used to quantify bone mineral density adjacent to the prosthesis. The results from the DEXA scan for cemented and the uncemented hips were analysed using Paired samples two tailed t-tests. To compare the Harris hip scores, a non-parametric Wilcoxon test was used. Pearson correlations were carried out to examine the relationship between the bone density measures (averaged for each zone) and the quality of life measures.

Results: Bone mineral density was higher on the Furlong side in Gruen Zones 2, 3, 5 and 6 of the proximal femur and DeLee Charnley Zone 1 of the acetabulum. In all other zones there was no statistical difference. Comparison of Harris hip scores and Oxford hip scores showed no statistically significant difference between the two hips (p = 0.108). Age is negatively correlated with bone density in Gruen zones 6 and 7 and acetabular zones 2 and 3.

Conclusion: Bone density is better preserved around the uncemented HAC coated stem compared to the Charnley cemented stem.

A prospective, comparative study of two Total Knee Replacement systems was undertaken to compare the traditional end point of revision of the prosthesis with three other end points based on the British Orthopaedic Association Knee Assessment Protocol. These were an unacceptable pain score plus revision, Knee Score of 60% or less plus revision, and a fall to below the preoperative Knee Score plus revision. 182 Knees entered the trial (74 St Leger and 108 Miller-Galante 11 prostheses), and all were assessed for Knee Score pre-operatively. Patients were subsequently assessed for Knee Score at 6 months, 1 year and annually thereafter. 63 implants had reached the five year stage at the time of this study.

The results indicate that different patients are designated as ‘failures’ depending on the end point selected, and that different survivorship figures can therefore be calculated with up to 6% variation depending on the end point used. In addition, the most successful prosthesis varies with the end point selected. Although the 95% confidence intervals in this study did not permit us to draw any firm conclusions, we suggest that further investigation into the definition of failure in survivorship analysis is necessary in order to reflect the performance as well as the longevity of Total Knee Replacements.