Ultrasound-Based Anatomical Assessment of the Most Common Shoulder Soft Tissue Injuries in Young Adults

Introduction: Shoulder pain is one of the leading causes of medical consultation, highlighting the need to identify the most frequently affected tissues to improve diagnosis. This study aims to determine the most common shoulder soft tissue injuries in young adults using musculoskeletal ultrasound (US). Methods: An observational cross-sectional study was conducted with 66 individuals aged 18 to 45 years; 35 participants reported shoulder pain and 31 did not. All participants received shoulder US by a specialist. Structures analyzed included the rotator cuff tendons, the long head of the biceps tendon (LHBT), and the subacromial-subdeltoid bursa. Results: The supraspinatus tendon was the most frequently affected structure, accounting for 65.1% of clinical findings, and its involvement was strongly associated with subscapularis tendinitis (OR = 18.45). The subscapularis tendon represented 31.8%, tenosynovitis of the LHBT occurred in 7.6%, and the subacromial-subdeltoid bursa was affected in 1.5%. Cluster analysis revealed three distinct profiles based on age, pain status, and tendon involvement: Cluster 1 (n = 23; mean age 21.6 ± 3.8 years) included younger individuals with minimal pain and tendinopathy (21.7%); Cluster 2 (n = 21; mean age 33.6 ± 2.6) consisted of intermediate-age participants with moderate pain and predominant supraspinatus tendinitis (71.4%); and Cluster 3 (n = 22 mean age 42.1 ± 1.6) comprised older individuals with the highest prevalence of pain and combined tendon lesions (81.8%). Conclusions: This study confirms the clinical value of musculoskeletal US in detecting soft tissue injuries, including subclinical findings. The supraspinatus tendon was the most frequently affected structure, often associated with subscapularis tendinitis and other combined lesions in older individuals. US proved useful in identifying distinct injury profiles based on age and pain status, supporting its role in early diagnosis and tailored management strategies.