Periarticular muscle dysfunction in knee osteoarthritis: clinical relevance, assessment, and management

Periarticular muscle abnormalities are common in knee osteoarthritis (KOA), but atrophy, weakness, adverse muscle composition, and impaired activation are not interchangeable. This mini review distinguishes their clinical relevance from their present capacity to guide treatment. Longitudinal evidence links knee-extensor weakness to incident KOA; evidence for structural worsening is less certain. Muscle imaging and activation measures provide additional information, but neither validated muscle phenotypes nor superior outcomes from phenotype-matched care have been established. A decision-linked assessment should begin with symptoms, patient-priority activities, functional performance, and strength. Imaging, laboratory activation testing, and sarcopenia assessment are added selectively. Exercise and, for people with overweight or obesity, weight management remain core care. Resistance, aerobic, neuromuscular, mind-body, and task-specific strategies can be adapted to measured impairments and patient preferences without requiring a mechanistic label. Pain and effusion deserve attention when activation is limited; electrical stimulation and blood flow restriction require qualified interpretation of their evidence. Nutritional assessment and monitoring of strength are relevant during intentional weight reduction as well as in patients at risk of sarcopenia. Human inflammatory-biomarker findings remain heterogeneous, and ferroptosis is a preclinical hypothesis. The proposed framework organizes assessment and treatment discussions; it is not a validated classification or evidence that muscle-focused care modifies structural progression.