Unicondylar arthroplasty of the knee—cheap at half the price?

Between June 1999 and October 2002 we performed 355 total knee replacements (75 bilateral cases) and 135 medial unicondylar arthroplasties (27 bilateral cases). The cases were not randomised with the result that those undergoing total knee replacement had more severe disease though not enough to account for the differences observed. The total knees were in hospital 4 days longer than the unicondylar knees (8.2 days compared with 4.1 days). Bilateral cases stayed on average 1 day longer than unilateral cases. Unicondylar knees did not require blood transfusion and none were given outpatient physiotherapy. The average saving for a unilateral unicondylar knee compared with a total knee was £1435 in the NHS sector and £2386 (30%) in the private sector. For bilateral cases the savings were £2287 and £3615 (29%), respectively. The biggest saving was between bilateral unicondylar knees and two unilateral total knees being £3480 in the NHS and £6578 (42%) in the private sector. Such differences almost certainly apply to different systems of delivering healthcare in other countries.