Background

Infiltration of muscle with non-lean tissue, such as fat, reduces muscle quality. Ultrasound captures muscle quality through measurement of echogenicity. Given the potential implications of quadriceps muscle quality on physical function, particularly in knee osteoarthritis, the purpose of this study was to investigate the relationship between echogenicity, muscle thickness and subcutaneous fat thickness with the clinical severity of osteoarthritis.

Methods

Thirty-one women with clinical knee osteoarthritis participated. Rectus femoris and vastus lateralis echogenicity, muscle thickness and subcutaneous fat thickness were measured from ultrasound images of the most symptomatic knee. Clinical severity of osteoarthritis was characterized with pain, self-reported function, six-minute walk test, and knee extensor strength. Correlation coefficients were calculated between muscle and fat architecture outcomes (muscle quality, muscle and fat thicknesses) and osteoarthritis clinical severity outcomes.

Findings

Data from 25 women were of sufficient quality for analysis. Echogenicity (muscle quality) related to the six-minute walk test for both rectus femoris (r = −0.52, p = 0.02) and vastus lateralis (r = −0.74, p = 0.004), with poorer muscle quality related to lower mobility. Subcutaneous fat thickness was related to the six-minute walk test (rectus femoris, r = −0.61, p = 0.0012; vastus lateralis, r = −0.73, p = 0.003) and strength (rectus femoris, r = −0.46, p = 0.02; vastus lateralis, r = −0.59, p = 0.03). Muscle thickness was not related to any severity outcomes.

Interpretation

Muscle quality, rather than thickness, is associated with mobility performance in women with knee osteoarthritis. Thus, interventions for osteoarthritis that specifically target muscle quality, rather than size, should be explored.

中文翻译：

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评估膝关节骨关节炎妇女使用超声捕获的股四头肌质量与临床严重程度之间的关系。

背景

肌肉被非瘦组织（例如脂肪）浸润会降低肌肉质量。超声波通过测量回声来捕获肌肉质量。考虑到股四头肌肌肉质量对身体功能的潜在影响，特别是在膝部骨关节炎中，本研究的目的是研究回声性，肌肉厚度和皮下脂肪厚度与骨关节炎的临床严重性之间的关系。

方法

参加临床膝骨关节炎的31名妇女。从症状最严重的膝盖的超声图像中测量股直肌和股外侧肌的回声，肌肉厚度和皮下脂肪厚度。骨关节炎的临床严重程度以疼痛，自我报告的功能，六分钟步行测试和膝盖伸肌力量为特征。计算肌肉和脂肪结构结局（肌肉质量，肌肉和脂肪厚度）与骨关节炎临床严重程度结局之间的相关系数。

发现

来自25名妇女的数据足以进行分析。股直肌（r  = -0.52，p  = 0.02）和股外侧肌（r  = -0.74，p  = 0.004）的六分钟步行测试的回声性（肌肉质量），较差的运动质量与较差的肌肉质量有关。皮下脂肪厚度与六分钟步行测试（股直肌，r  = -0.61，p  = 0.0012；侧股阔肌，r  = -0.73，p  = 0.003）和强度（股直肌，r  = -0.46，p  = 0.02;股外侧肌，r  = −0.59，p = 0.03）。肌肉厚度与严重程度无关。

解释

肌肉质量而不是厚度与膝骨关节炎妇女的活动能力有关。因此，应该研究专门针对肌肉质量而非大小的骨关节炎干预措施。