Musculoskeletal · Shoulder Pathology
The facts most likely to be tested
The supraspinatus is the most commonly injured tendon in the rotator cuff due to its location in the subacromial space and its susceptibility to impingement.
Patients with a rotator cuff tear present with shoulder pain that is exacerbated by overhead activity and night pain when sleeping on the affected side.
The Drop Arm Test is highly specific for a full-thickness rotator cuff tear, characterized by the patient's inability to slowly lower the arm from 90 degrees of abduction.
The Empty Can Test (Jobe test) is the most sensitive physical exam maneuver to assess for supraspinatus pathology.
Magnetic Resonance Imaging (MRI) is the gold standard diagnostic modality to confirm the diagnosis and evaluate the size and retraction of the tear.
Initial management for most rotator cuff tears includes physical therapy, NSAIDs, and activity modification, reserving surgical repair for patients who fail conservative therapy or have acute, traumatic full-thickness tears.
Weakness on external rotation is a classic clinical finding that suggests involvement of the infraspinatus or teres minor muscles.
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A 58-year-old male construction worker presents with a 3-month history of right shoulder pain. He reports difficulty reaching for tools on high shelves and states the pain is worse at night. On physical exam, he has pain with abduction and demonstrates a positive Drop Arm test. There is weakness with resisted external rotation of the shoulder. Passive range of motion is preserved.
What is the most appropriate next step in the management of this patient?
Physical therapy and NSAIDs
The patient's presentation is classic for a rotator cuff tear; initial management for chronic, non-traumatic tears is conservative therapy, as surgery is reserved for those who fail to improve after 3-6 months.
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Etiology / Epidemiology
Common in repetitive overhead activity and age >40. Often involves the supraspinatus tendon.
Clinical Manifestations
Presents with weakness and pain with overhead reaching. Positive Drop Arm test is pathognomonic.
Diagnosis
MRI is the gold standard for definitive diagnosis. Ultrasound is a reliable initial imaging modality.
Treatment
Physical therapy and NSAIDs are first-line. Avoid corticosteroid overuse due to tendon weakening.
Prognosis
Most patients improve with conservative care; surgical repair is indicated for full-thickness tears or failure of 3-6 months of therapy.
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Epidemiology & Etiology
Prevalence increases significantly with age, particularly in patients >60 years old. Primary risk factors include repetitive overhead motion (e.g., swimming, painting) and acute trauma. Degenerative changes are common due to hypovascularity of the critical zone.
Pertinent Anatomy
The rotator cuff consists of the SITS muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. The supraspinatus is the most commonly injured tendon due to its location beneath the acromion.
Pathophysiology
Chronic impingement leads to mechanical wear and eventual tendon failure. The subacromial space narrows, causing friction during abduction. This progresses from tendinopathy to partial-thickness and finally full-thickness tears.
Clinical Manifestations
Patients report anterolateral shoulder pain exacerbated by overhead activity. Physical exam reveals weakness with abduction and external rotation. The Drop Arm test and Empty Can test are highly specific. Red flags include night pain and significant atrophy of the supraspinatus or infraspinatus fossae.
Diagnosis
Clinical diagnosis is supported by physical exam maneuvers. MRI is the gold standard for visualizing tear size and retraction. Ultrasound is a cost-effective alternative for dynamic assessment of the rotator cuff.
Treatment
Initial management involves NSAIDs, activity modification, and physical therapy focusing on rotator cuff strengthening. Corticosteroid injections should be used sparingly to avoid tendon degradation. Surgical intervention is reserved for full-thickness tears or patients who fail 3-6 months of conservative management.
Prognosis
Conservative management is successful in the majority of partial tears. Surgical repair outcomes are best when performed before significant muscle atrophy or fatty infiltration occurs.
Differential Diagnosis
Subacromial Impingement: pain without significant weakness
Adhesive Capsulitis: global loss of active and passive range of motion
Glenohumeral Arthritis: crepitus and joint space narrowing on X-ray
Cervical Radiculopathy: pain radiating below the elbow with neck movement
Biceps Tendonitis: tenderness localized to the bicipital groove