Muscle damage during minimally invasive surgical total knee arthroplasty traditional versus optimized subvastus approach

Decreased muscle damage is reported as an advantage of minimally invasive surgical (MIS) approaches in total knee arthroplasty (TKA). The purpose of this study was to evaluate the anatomy of vastus medialis obliquus (VMO) tendon at its patellar insertion as well as to determine the amount and location of muscle damage comparing traditional subvastus approach and optimized subvastus approach. TKAs were performed in ten human cadavers (20 knees). In each specimen, one knee underwent the traditional subvastus approach and the contralateral knee the optimized subvastus approach. The risk of tearing and damaging the VMO muscle during the traditional subvastus approach is significantly higher (70% of the cases) compared to the optimized technique (30%). The amount of damage to the VMO muscle using the traditional subvastus approach was: 80% of the muscle's width in two cases, 60% in three cases, and 30% in two. The damage created by the optimized subvastus approach occurred along the edge of the tendon and the first fibers of the VMO muscle close to the muscle-tendon junction (less than 20% of muscle's width). Clinical studies are needed to determine the functional implications of these findings.