Unicompartment total knee replacement: a 2--4 year review.

Unicompartment total knee replacement is a controversial operation. Conflicting reports indicate that there is unacceptable wear associated with loosening. To investigate the problem, 21 patients were examined 2--4 years after the operation. Eighty-one per cent of the patients were free of pain. None of the remaining patients had disabling pain. All patients demonstrated 90 degrees or greater range of motion with 91% of the patients' preoperative deformity completely corrected. There was a 19% evidence of X-ray loosening of the component which was consistently associated with the clinical symptoms of mild pain. Unicompartment total knee replacement is an acceptable alternative to high tibial osteotomy and relieves pain as well as corrects deformity.