Isotope bone scans in patients with painful knee replacements: do they alter management?

A retrospective review of the scintigraphic appearances, clinical findings and outcome in 12 patients presenting with painful knee replacements was made. Three patients required revision surgery; symptoms in the remaining nine patients settled without operative management. Three examinations failed to identify prostheses proven to be infected by aspiration and four were falsely positive for infection without supportive clinical evidence. Four examinations demonstrated loosening and in one patient the bone scan was normal but the prostheses was loose at revision surgery. There were no specific features to predict which prostheses required surgical revision and the ability to diagnose or exclude infection was limited. It is concluded that the results of three phase 99Tcm bone scans in symptomatic knee prostheses are of little assistance in guiding clinical management and that a period of conservative management should be considered prior to operative intervention.