Using the General Practice Research Database, we examined the temporal changes in the rates of primary total hip (THR) and total knee (TKR) replacement, the age at operation and the female-to-male ratio between 1991 and 2006 in the United Kingdom.

We identified 27 113 patients with THR and 23 843 with TKR. The rate of performance of THR and TKR had increased significantly (p < 0.0001 for both) during the 16-year period and was greater for TKR, especially in the last five years. The mean age at operation was greater for women than for men and had remained stable throughout the period of study. The female-to-male ratio was higher for THR and TKR and had remained stable.

The data support the notion that the rate of joint replacement is increasing in the United Kingdom with the rate of TKR rising at the highest rate. The perception that the mean age for TKR has decreased over time is not supported.

Balancing service provision and surgical training is a challenging issue that affects all healthcare systems. A multicentre prospective study of 1501 total hip replacements was undertaken to investigate whether there is an association between surgical outcome and the grade of the operating surgeon, and whether there is any difference in outcome if surgeons’ assistants assist with the operation, rather than orthopaedic trainees. The primary outcome measure was the change in the Oxford hip score (OHS) at five years. Secondary outcomes included the rate of revision and dislocation, operating time, and length of hospital stay.

There was no significant difference in ΔOHS or complication rates between operations undertaken by trainers and trainees, or those at which surgeons’ assistants and trainees were the assistant. However, there was a significant difference in the duration of surgery, with a mean reduction of 28 minutes in those in which a surgeons’ assistant was the assistant.

This study provides evidence that total hip replacements can be performed safely and effectively by appropriately trained surgeons in training, and that there are potential benefits of using surgeons’ assistants in orthopaedic surgery.

Survival analysis of joint replacement relies on the assumption that surgical procedures in patients lost to follow-up have the same chance of failing as those in patients who continue to be assessed. Our study questions that assumption.

During the 16-year follow-up of 2268 patients who had received total hip replacements 142 (6%) were lost to follow-up. The cumulative loss at 15 years was 20%. At their last assessment, patients who subsequently failed to attend for follow-up had significantly worse pain, range of movement and opinion of their progress (p < 0.001) and significantly worse radiological features than a matched control group (p < 0.01).

Patients lost to follow-up have a worse outcome than those who continue to be assessed. Consequently, a survival analysis that does not take into account such patients is likely to give falsely optimistic results. It is therefore essential that vigorous attempts are made to minimise loss to follow-up, and that the rate of such loss is quoted. The overall loss to follow-up disguises the magnitude of the problem, which is best quantified by a cumulative rate of follow-up.

The reliability of a study can be assessed by a loss-to-follow-up quotient, calculated by the number of failures: the lower the quotient the more reliable the data. Ideally, the quotient should be less than 1.