Effect of arthroscopic partial meniscectomy on the function of quadriceps femoris.

The purpose of this study was to investigate the functional characteristics of the quadriceps femoris (QF) muscle group after the effect of presurgery disuse, surgery, and postsurgery disuse using surface electromyography and muscle functional magnetic resonance imaging (mfMRI). A total of 20 individuals (11 men and nine women) who underwent arthroscopic knee surgery participated in this study. Maximum voluntary contraction (MVC) of the QF muscle group was measured in the legs that received surgery and those that did not. To acquire the functional properties of the QF muscle group, electromyographic (EMG) activity during repetitive dynamic knee extension exercises (five sets of ten repetitions; load 30% MVC) and mfMRI before and after the exercises were obtained. EMG activity was evaluated in three phases depending on the knee joint angle: concentric and eccentric phases (Con/Ecc), concentric (Con) phase only, and eccentric (Ecc) phase only. The mean MVC of the legs that received surgery was significantly lower (22%) than that of the legs that did not. Regarding the EMG activity during the Con/Ecc and Con phases, there were significant leg and set effects but no significant leg-by-set interactions; however, during the Ecc phase, there was a significant set effect. Regarding changes in the mfMRI signal, leg and exercise had significant effects, but there was no significant leg-by-exercise interaction. These results suggest that presurgery disuse, partial meniscectomy, and postsurgery disuse induce dysfunction of the QF muscle group that is dependent on a decrease in MVC. Thus, these patients need maximal muscle-force improvement for effective rehabilitation after surgery.