DOI: 10.1080/16501970510035070

Objective: The purpose of this study was to compare extensor mechanism function using a sit-to-stand test in patients undergoing uni- and bilateral total knee replacement, with a 6-month follow-up. Design: Prospective controlled study. Patients: The series included 72 patients with total knee replacement (unilateral 32 patients, bilateral 40 patients). Methods: All patients were evaluated pre-operatively by the physiotherapist and then at 2-weekly intervals during the postoperative 6 months using Hospital for Special Surgery knee score, and range of motion. Extensor mechanism function was evaluated at the same time points using a sit-to-stand test. Results: At the end of study, there was no difference between the groups in their knee range of motion and Hospital for Special Surgery scores (p >0. 05). There was a significant difference between the groups in their chair rising ability (p <0. 05). At 2 weeks, 22% of patients in the group with unilateral total knee replacement and 20% of patients in the group with bilateral total knee replacement could rise independently. However, there was significant difference in favour of unilateral total knee replacement at 4, 6, 8 and 10 weeks. At 10 weeks, all patients in the group with unilateral total knee replacement and at 6 months all patients in the group with bilateral total knee replacement could rise independently. Conclusion: We conclude that patients with unilateral total knee replacement gain independence earlier than patients with bilateral total knee replacement. However, for patients with bilateral total knee replacement eventually to gain independence, they should be prepared for a longer rehabilitation programme.