Shoulder Impingement Syndrome: AI-Powered MRI Analysis

Shoulder impingement results from mechanical compression of the supraspinatus tendon and subacromial bursa between the humeral head and the coracoacromial arch during arm elevation. Primary impingement is caused by structural narrowing — a hooked (type III) acromion, os acromiale, or hypertrophic acromioclavicular joint — that reduces the subacromial space below its normal 7–10 mm. Secondary impingement occurs when rotator cuff weakness, glenohumeral instability, or scapular dyskinesia causes dynamic superior migration of the humeral head. Repetitive overhead activities in athletes and manual laborers accelerate subacromial bursal thickening and tendinopathic change in the supraspinatus critical zone.

On MRI, subacromial impingement without a tear demonstrates subacromial-subdeltoid bursal thickening and fluid, peritendinous edema, and increased signal within the supraspinatus on T2-weighted fat-suppressed images without a discrete through-and-through defect. Coronal-oblique T2-FS sequences are the primary plane for evaluating the supraspinatus tendon. A hooked acromion or inferior acromioclavicular osteophytes narrowing the subacromial space are visible on sagittal images. Full-thickness rotator cuff tears are distinguished by fluid signal traversing the entire tendon thickness. Axial T2-FS images complement coronal sequences by evaluating the subscapularis and long head of the biceps tendon.

Conservative management successfully resolves symptoms in the majority of patients with impingement syndrome. Physical therapy targeting posterior capsule stretching, rotator cuff strengthening, and scapular stabilization is the cornerstone of treatment. NSAIDs and a subacromial corticosteroid injection provide short-term pain relief to facilitate rehabilitation. Activity modification to avoid provocative overhead postures is essential. Surgical intervention — arthroscopic subacromial decompression with acromioplasty — is reserved for patients with persistent symptoms after at least 3–6 months of dedicated conservative therapy. Concomitant rotator cuff pathology identified on MRI or at arthroscopy is addressed at the same operative setting.