Minimally invasive total knee replacement through a mini midvastus approach: a comparative study.

Between September 2001 and September 2002, forty consecutive minimally invasive total knee replacements were done. A modified midvastus approach was used and the patella was subluxed, but not everted. We compared the results of this group with an age-matched and sex-matched cohort of total knee replacements done between June 2000 and September 2001 with a standard technique. A posterior-stabilized knee (Genesis II) was used in both groups. Patients achieved motion considerably faster in the minimally invasive total knee replacement group. Mean flexion for minimally invasive total knee replacement at 6 and 12 weeks was 114 degrees (range, 90-132 degrees ) and 122 degrees (range, 103-135 degrees ) respectively, compared with 95 degrees (range, 65-125 degrees ) and 110 degrees (range, 80-125 degrees ) for the control group. Improved range of motion was also seen at one year postoperatively. The average range of motion at one year postoperatively in the minimally invasive total knee replacement was 125 degrees (range, 110-135 degrees ) compared with 116 degrees (range, 95-130 degrees ) in the Control Group. Postoperative Knee Society scores were also higher in the minimally invasive total knee replacement group. There was no difference in xray alignment. There were no infections, extensor mechanism or neurovascular complications. The mini midvastus approach without patella eversion combined with a small incision was associated with a more rapid functional recovery and improved range of motion in total knee replacement without compromising implant positioning.