Minimally invasive total knee arthroplasty: the mini midvastus approach.

Minimally invasive knee surgery offers the potential for earlier return of motion. To ascertain whether this potential is realized we retrospectively reviewed 335 consecutive patients (391 knees) who underwent minimally invasive total knee arthroplasties from September 2001 to September 2004 using the mini midvastus approach. There were 248 women and 87 men, with an average preoperative range of motion (ROM) of 109 degrees. Sixty-three percent of patients had a body mass index of less than 30% and 33% had a body mass index from 30 to 39. Patients received epidural anesthesia and a posterior-stabilized knee. We obtained Knee Society scores and determined ROM. The mean ROM at 6 weeks postoperatively was 111 degrees, 121 degrees at 3 months, and 125 degrees at 1 year and 2 years postoperatively. Knee Society scores were 95 or over at all followup periods. Postoperative ROM was related to preoperative ROM, although patients with less preoperative motion had the greatest improvements at 6 weeks and 3 months postoperatively. We observed no increased complication rate with this approach. Minimally invasive total knee arthroplasty with a mini midvastus approach was associated with rapid functional recovery and substantial improvements in ROM. This procedure can be performed safely and provides high Knee Society scores short term.