Evaluation of skeletal muscle metabolism during walking in symptomatic and asymptomatic patients with osteoarthritis of the knee joint using positron emission tomography.

Abstract

This study aimed to evaluate skeletal muscle metabolism during walking in symptomatic and asymptomatic patients with knee osteoarthritis using positron emission tomography-computed tomography with 18F-fluorodeoxyglucose. We hypothesized that quadriceps muscle metabolism during walking would vary between the groups. Twenty-two participants (11 males and 11 females) with knee osteoarthritis (Kellgren-Lawrence grade 2) were divided into symptomatic and asymptomatic groups. The participants performed two 10-min walks on a treadmill, received an intravenous injection of 18F-fluorodeoxyglucose between sets, and underwent positron emission tomography-computed tomography. Regions of interest were manually segmented into 35 skeletal muscles from the pelvis to the foot. The standardized uptake value was calculated to quantitatively examine 18F-fluorodeoxyglucose uptake by muscle tissue. The mean standardized uptake values of the hip abductor and external rotator muscles were lower in the symptomatic group than in the asymptomatic group and displayed a medium effect size (gluteus medius, P = 0.281; d = 0.482; gluteus minimus, P = 0.079; d = 0.793; piriformis, P = 0.184; d = 0.622). Although the vastus medialis demonstrated a medium effect size (P = 0.191; d = 0.597), the rectus femoris (P = 0.454; d = 0.299), vastus lateralis (P = 0.303; d = 0.392), and vastus intermedius (P = 0.300; d = 0.434) demonstrated no significant differences and only small effect sizes. Therefore, no overall difference in quadriceps muscle metabolism was observed between the groups. A trend towards lower hip abductor and external rotator muscle metabolism was observed in patients with symptomatic knee osteoarthritis, suggesting that muscle metabolism may be associated with knee symptoms.