Forearm Muscle and Tendon Thickness in Rotator Cuff-Related Shoulder Pain

Rotator cuff-related shoulder pain (RCRSP) is one of the most common musculoskeletal disorders affecting the shoulder and is frequently associated with pain, reduced muscle strength, and impaired upper extremity function. Although previous studies have primarily focused on structural and functional changes around the shoulder, little is known about the potential adaptations occurring in the distal upper extremity, particularly the forearm muscles and tendons. Altered upper extremity use, pain-related muscle inhibition, and compensatory movement patterns associated with prolonged shoulder pain may lead to morphological changes in the forearm musculature and tendons. However, the relationship between symptom duration and these structural adaptations has not yet been investigated. The aim of this cross-sectional study is to evaluate forearm muscle and tendon thickness using portable ultrasonography in individuals with RCRSP and to investigate whether these parameters differ according to symptom duration. In addition, hand grip strength, pain intensity, and upper extremity function will be assessed to explore their associations with ultrasonographic findings. The findings of this study are expected to provide new insights into distal upper extremity adaptations associated with RCRSP and may contribute to the development of more comprehensive rehabilitation strategies that address not only the shoulder but also the forearm musculature.