Strength and Voluntary Activation of Quadriceps Femoris Muscle in Total Knee Arthroplasty with Midvastus and Subvastus Approaches

To determine and compare the influence of 2 different approaches on quadriceps femoris muscle function in total knee arthroplasty (TKA), 20 patients (14 women, 6 men) with bilateral knee osteoarthritis underwent a 1-stage bilateral TKA. Surgical approaches (subvastus, midvastus) were performed by a random selection. Measurements of quadriceps voluntary activation and maximal voluntary contraction were estimated by a twitch interpolation technique before, 3 and 6 months after TKA. Knee pain was quantified by the Lewis Score. There was no difference between the 2 approaches at 3 and 6 months after TKA with regard to maximal voluntary contraction (P = 0.84, F = 0.041) and voluntary activation (P = .863, F = 0.031). In the subvastus group was a significantly higher knee pain until 6 months after surgery (P = .02). The subvastus approach for TKA does not provide any advantages compared with the midvastus approach with respect to the quadriceps femoris muscle strength in the early postoperative period. Furthermore, the subvastus approach caused significantly more pain postoperatively.