A prospective randomized study of minimally invasive total knee arthroplasty compared with conventional surgery.

BACKGROUND Despite intense debate regarding whether minimally invasive techniques for total knee arthroplasty improve clinical outcomes over standard techniques, few prospective randomized trials addressing this debate are available in the literature. We therefore designed this multicenter study to assess the overall safety and effectiveness of a minimally invasive approach without the use of computer navigation in comparison with conventional knee arthroplasty. METHODS We prospectively randomized 134 patients (101 women and thirty-three men, with an average age of 70.1 years) to undergo surgery for total knee arthroplasty with use of either minimally invasive knee instruments (sixty-six patients) or a standard approach (sixty-eight patients). The follow-up period was one year. RESULTS On the basis of our sample size, no significant difference was detected between the groups in any of the relevant clinical areas assessed: total range of motion, Knee Society total and function scores, and visual analog scores for pain and activities of daily living. Patients who underwent minimally invasive surgery had a longer mean surgical time (by 5.6 minutes) and had less mean blood loss (by 17 mL). Radiographic measurements demonstrated reliable implant positioning in both groups. Seven patients in each group had an adverse event related to their procedure. CONCLUSIONS On the basis of the numbers, no significant advantage to minimally invasive total knee arthroplasty over a conventional technique was observed. Greater sample sizes and a longer follow-up period are required to fully determine the long-term safety and efficacy of this minimally invasive surgical technique.