Popliteus and Quadriceps Muscle Thickness and Clinical Parameters in Knee Osteoarthritis

This study aims to examine the relationships between the ultrasonographic muscle thicknesses of the popliteus and quadriceps muscles and functional capacity, balance, and pain levels in elderly patients with knee osteoarthritis (KOA). Knee osteoarthritis is a major degenerative joint disorder causing pain, stiffness, and reduced mobility, where surrounding muscle architecture plays a pivotal role in functional performance and joint stability. The study will recruit approximately 150 participants aged 65 years and older with Grade 3-4 KOA (Kellgren-Lawrence) and intact cognitive status (SMMSE score ≥24) presenting to the Physical Medicine and Rehabilitation Outpatient Clinic of Afyonkarahisar Health Sciences University Health Application and Research Center, while excluding individuals with central nervous system, visual pathologies, or prior lower extremity surgeries. Muscle thicknesses of the popliteus and quadriceps (rectus femoris and vastus intermedius) will be measured via high-frequency B-mode ultrasonography by a specialist physician, using standardized anatomical landmarks and patient positioning. Functional capacity and mobility will be evaluated using the Timed Up and Go (TUG) and 5-Times Sit-to-Stand (5STS) tests, balance and proprioception via the Romberg Test, and knee-specific functional status and pain severity using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Visual Analog Scale (VAS).