Estimation of muscle atrophy based on muscle thickness in knee surgery patients.

The purpose of this study was to establish an accurate estimation of muscle atrophy in the quadriceps femoris (QF) muscle group. Eighteen individuals who underwent meniscectomy participated in the study (nine men and nine women, mean age 44·4 years). Both operated and non-operated thighs were scanned by magnetic resonance imaging to determine the volume and thickness of the QF muscle group. Muscle volume was estimated using eleven axial images, and muscle thickness was measured at the anterior, lateral and medial regions of the proximal, mid- and distal thigh, respectively. A stepwise linear regression analysis was performed to obtain the relationship between the difference in muscle volume and the difference in muscle thickness between operated and non-operated limbs. There was no significant difference in muscle volume of the QF between operated (806·6 ± 220·0 cm(3) ) and non-operated (913·7 ± 241·5 cm(3) ) limbs. Based on the stepwise linear regression analysis, the difference in muscle volume was significantly correlated with the difference in muscle thickness at the anterior proximal thigh and lateral mid-thigh and anterior mid-thigh (R = 0·93, P<0·01). In conclusion, the difference in muscle volume between operated and non-operated limbs can be estimated accurately by measuring muscle thickness of the QF at three sites: the anterior proximal thigh, the lateral mid-thigh and anterior mid-thigh. Muscle thickness can be measured easily using imaging techniques such as ultrasonography. We propose that this method provides an easy and accurate estimate of knee surgery-induced muscle atrophy in clinical medicine.

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.

Atrophy of thigh muscles after meniscal lesions and arthroscopic partial menisectomy.

The purpose of this study was to investigate the atrophic pattern of the muscle groups and their individual muscles in the thigh after meniscal lesions and arthroscopic partial menisectomy. A total of 32 individuals (17 men and 15 women) who underwent arthroscopic knee surgery participated in this study. Their operated and non-operated thighs were scanned by magnetic resonance imaging to determine the volume of the quadriceps (QF), hamstring (HM), and adductors (AD). Compared with the non-operated limb, the volume of the QF was significantly lower in the operated limb; however, no significant difference was observed in the HM and AD. The volume of individual muscles of the QF, i.e. the rectus femoris (RF), vastus lateralis (VL), vastus intermedius (VI), and vastus medialis (VM), in the operated limb was significantly lower than the volume of those in the non-operated limb (P<0.01, all). Although the relative change in the VM was significantly higher than that of the RF (P<0.05), specific atrophy was not found among four individual muscles in the QF. We concluded that meniscal lesions and partial menisectomy induce atrophy in the QF only in the thigh, and that no specific atrophy, e.g. VM, seemed to occur within the individual muscles in the QF.