Electromyographic Evaluation of the Midvastus Approach☆

Abstract 

Compared with the standard median parapatellar approach, the muscle-splitting midvastus approach to the knee has led to claims of an easier and earlier recovery after total knee arthroplasty, but some investigators have questioned whether the midvastus approach damages the vastus medialis obliquus. We used electromyographic and nerve conduction studies to evaluate whether we could document any such damage. Twenty patients undergoing bilateral total knee arthroplasty were randomized prospectively for the treatment of 1 knee with each of the 2 approaches. Radiographs, electromyographies, nerve conduction studies, range-of-motion tests, and Knee Society function and pain tests were conducted preoperatively and at 6 weeks postoperatively. If the electromyography or nerve conduction tests were abnormal at 6 weeks, the tests were repeated at 12 weeks. At the final follow-up, these studies showed no evidence of muscle denervation. The midvastus approach appears to be a safe alternative for knee arthrotomy for total knee arthroplasty without concerns for damage to the vastus medialis obliquus.

Key words: electromyography, midvastus approach, total knee arthroplasty, parapatellar approach, outcome