ObjectivesIt has been reported that low skeletal muscle mass correlates with knee osteoarthritis in obese individuals. This study aimed to investigate whether lower limb skeletal muscle mass is independently associated with knee osteoarthritis in the general population.Materials and MethodsThis cross-sectional study used public data from the Fourth and Fifth Korean National Health and Nutrition Examination Survey. Subjects included 4924 community-dwelling adults aged ≥50 years (821 subjects with knee osteoarthritis and 4,103 controls). Skeletal muscle mass index (SMI) was calculated from the appendicular skeletal muscle mass measured by dual energy X-ray absorptiometry. Independent effects of total and lower limb SMI values on knee osteoarthritis were determined using odds ratios (OR) adjusted for age, sex, obesity, total femur bone mineral density, serum vitamin D level, diabetes mellitus status, and physical activity on multivariate logistic regression analysis.ResultsThe adjusted logistic regression model revealed that older age, female sex, and obesity were significantly associated with knee osteoarthritis. A higher serum vitamin D level was also positively correlated with knee osteoarthritis (OR, 1.015; 95% CI, 1.003–1.027; P = 0.010). Although total SMI was not significantly associated with knee osteoarthritis (OR, 0.976; 95% CI, 0.946–1.007; P = 0.127), a low lower limb SMI had an independent effect on knee osteoarthritis (OR, 0.941; 95% CI, 0.900–0.983; P = 0.006).ConclusionsLow skeletal muscle mass in the lower limbs but not in the whole body was independently associated with knee osteoarthritis.

ObjectiveTo investigate the relationships between respiratory muscle strength and conventional sarcopenic indices such as skeletal muscle mass and limb muscle strength.MethodsEighty-nine young adult volunteers who had no history of medical or musculoskeletal disease were enrolled. Skeletal muscle mass was measured by bioelectrical impedance analysis and expressed as a skeletal muscle mass index (SMI). Upper and lower limb muscle strength were evaluated by hand grip strength (HGS) and isometric knee extensor muscle strength, respectively. Peak expiratory flow (PEF), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) were evaluated using a spirometer to demonstrate respiratory muscle strength. The relationships between respiratory muscle strength and sarcopenic indices were investigated using Pearson correlation coefficients and multiple linear regression analysis adjusted by age, height, and body mass index.ResultsMIP showed positive correlations with SMI (r=0.457 in men, r=0.646 in women; both p<0.01). MIP also correlated with knee extensor strength (p<0.01 in both sexes) and HGS (p<0.05 in men, p<0.01 in women). However, PEF and MEP had no significant correlations with these sarcopenic variables. In multivariate regression analysis, MIP was the only independent factor related to SMI (p<0.01).ConclusionAmong the respiratory muscle strength variables, MIP was the only value associated with skeletal muscle mass.

Introduction:We report a case of an infant with severe white matter injury (WMI), which was serially evaluated using diffusion tensor imaging (DTI).Case presentation:A male infant showed decreased muscle tone and weak breathing. A brain magnetic resonance imaging (MRI) 10 days after birth (first study) revealed diffuse microhemorrhages and encephalomalacia. DTI revealed lack of reconstruction of corticospinal tract (CSTs), minimal reconstruction of medial lemniscus, and related thalamocortical pathways (MLs) from the brain stem to the internal capsule level on the left side. The spinothalamic tract and related thalamocortical pathways (STTs) were reconstructed from the brain stem to the internal capsule level bilaterally. The second study one year later showed the absence of reconstruction of CSTs, but reconstruction of MLs and STTS from the brain stem to above the internal capsule showed increased visualization. The third study 3 years later still showed the absence of CSTs reconstruction and MLs and STTs showed no changes from the second study. During this 3-year observation period, the patient showed minimal motor development, and was unable to walk independently, although Gross Motor Function Measure (GMFM) scores were slightly increased.Lessons:Sustained disconnection of major sensorimotor pathways after WMI confirmed by DTI was used to predict motor function outcome.

We found that side-to-side corticospinal tract differences were equalized after using bilateral prostheses. Clinical relevance This case report suggests that diffusion tensor imaging tractography could be a useful method to understand corticomotor reorganization after using prosthesis in transtibial amputation.