Minimally Invasive Total Knee Arthroplasty Does Not Improve Outcomes 1 Year after Surgery: A Randomized Controlled Trial

Abstract

Background: Within the past few years, minimally invasive surgical (MIS) techniques for total knee arthroplasy (TKA) have emerged as promising alternatives to conventional TKA, possibly because of less surgical trauma to the quadriceps. The purpose of this investigation was to evaluate the efficacy of MIS TKA outcomes compared to conventional TKA. Methods: Forty-four patients, aged 50-85 years (64.3 ± 8.4 mean ± SD; 22 females, 22 males) who were scheduled for a unilateral TKA secondary to osteoarthritis were enrolled in a prospective randomized controlled trial. Patients were excluded if they had cardiopulmonary, neurological, or other unstable orthopedic conditions that limited function; uncontrolled diabetes; or a BMI ≥ 40 kg/m2 . Patients were blinded and randomly assigned to one of two surgical groups: MIS or conventional. All patients completed a standardized course of rehabilitation following surgery. Patients were assessed preoperatively and 4, 12, 26, and 52 weeks postoperatively by a blinded evaluator; the 26- and 52-week outcomes are the focus of the present manuscript. Outcomes included isometric quadriceps strength (primary outcome), isometric hamstrings strength, quadriceps activation, active knee range of motion (AROM), the six-minute walk (6MW) test, pain at rest and with 6MW, timed-up-and-go test (TUG), the stair climbing test, the Short Form 36 Health Status questionnaire (SF-36) the Western Ontario and McMaster Osteoarthritis Index (WOMAC), and leg muscle mass. Results: There were no differences between groups at baseline. At 26 and 52 weeks postoperatively, there were no difference between MIS and control groups for any outcome measure. Conclusions: Although the MIS surgical technique for TKA may lead to faster recovery of strength in patients undergoing TKA (previously reported at 4 weeks postoperatively), there is no apparent benefit of MIS on the longerterm recovery of strength or functional performance. Therefore, the benefits of MIS TKA may not outweigh the risks associated with limited surgical visualization