The aim was to perform a cost-utility analysis of total joint replacement in the current environment.

Arthritis is a disabling condition that leads to long-term deterioration in quality of life. Total joint replacement, despite being one of the greatest advances in medicine in the modern era, has come under recent scrutiny. The National Health Service (NHS) has competing demands and resource allocation is challenging in times of economic restraint.

Patients undergoing total hip (n=348) and knee arthroplasty (n=323), from January to July 2010, were entered into a prospective arthroplasty database. A health utility score was derived from the Euroqol (EQ-5D) score preoperatively, and at one year, and was combined with individual life expectancy to derive the Quality-Adujusted-Life-Years (QALYs) gained. Predicted need for revision surgery was Incorporated in the model. The 2011–12 Scottish Tariff was used. Two-way analysis of variance was used to compare QALYs gained between procedures, while controlling for baseline differences.

The number of QALYs gained was higher in THR versus TKR (6.53 vs 4.04 years, p<0.001). The cost per QALY for THR was £1371 (95% CI £1194 to £1614) compared with £2101 (£1762 to £2620) for TKR. Predictors of an increase in QALYs gained were poorer health prior to surgery (p<0.001) and younger age (p<0.001). General health (EQ-5D VAS) showed greater improvement in THR versus TKR (p<0.001).

This study provides up to date cost-effectiveness data for total joint replacement. THR and TKR are both extremely clinically and cost-effective interventions, with costs that compare favourably with other medical interventions (e.g. laparoscopic hernia repair vs open: £55,548 per QALY; CHD primary prevention with statins: £21,000).

SIGN guidelines advise the use of flucloxacillin and gentamicin instead of cefuroxime as antibiotic prophylaxis for elective hip and knee arthroplasty. It is our impression that this change in practice has been associated with an increased risk of acute kidney injury (AKI).

During a twelve month period we examined the incidence of AKI sequentially in four groups of patients: cefuroxime prophylaxis (n = 46); high dose flucloxacillin (5-8g) with single shot gentamicin (n = 50); low dose flucloxacillin (1-4 g) with single shot gentamicin (n = 45); and finally cefuroxime again (n = 52).

There were no statistically significant differences by chi-square tests for age, gender, operation (hip or knee), ASA, anaesthesia, baseline serum creatinine, hypertension, diabetes or pre-operative medication. The proportion of patients in each antibiotic group with any form of AKI by RIFLE criteria was: cefuroxime group 1 (9%), high dose flucloxacillin (52%), low dose flucloxacillin (22%), cefuroxime 2 (14%) (p < 0.0001 by chi-square test). Odds ratios (OR) for AKI derived from a multivariate logistic regression model and assigning an OR of 1 to cefuroxime group 1 was: high dose flucloxacillin 14.5 (95% CI, 4.2, 50.2); low dose flucloxacillin 3.0 (0.8-10.9) and cefuroxime group 2 1.9 (0.5, 7.4). Three patients in the high dose flucloxacillin group required temporary haemodialysis.

We have shown a strong association between high dose prophylactic flucloxacillin and subsequent development of AKI. We have no reason to believe that this was confounded by any of the co-variates we measured.