Anatomical assessment of the vastus medialis oblique muscle in patients with osteoarthritis of the knee.

Minimally invasive total knee arthroplasty requires subluxation of patella laterally without eversion. The anatomy of the vastus medialis oblique muscle (VMO), which affects the surgical exposure of minimally invasive total knee arthroplasty, was investigated. There was no significant difference between men and women with respect to any parameter. The average fiber angle relative to the rectus femoris muscle was 52.9 degrees on anteroposterior view and 49.7 degrees on lateral view. The average insertion height and the distal portion of VMO belly were 17.3% and 38.4% of the patella length from the upper pole of patella, respectively. Female patients had lower VMO attachment and VMO belly, and a significant sex difference was demonstrated. All patients had attachments beneath the upper pole of the patella.