Residency · Residency · Family Medicine

Shoulder Pain: Rotator Cuff Pathology and Beyond

Overview

Shoulder pain is the third most common musculoskeletal complaint in primary care. The majority of cases involve rotator cuff pathology, but a systematic approach is essential to identify other causes including adhesive capsulitis, instability, acromioclavicular joint disease, and referred pain from cervical or visceral sources.

Anatomy

The glenohumeral joint is a ball-and-socket joint that offers exceptional mobility at the cost of inherent instability. The rotator cuff is composed of four muscles remembered by the mnemonic SITS: the supraspinatus (the most commonly injured, responsible for abduction), the infraspinatus (external rotation), the teres minor (external rotation), and the subscapularis (internal rotation). The glenoid labrum is a fibrocartilaginous rim that deepens the socket and provides stability. The acromioclavicular joint is the articulation between the distal clavicle and the acromion. The subacromial space contains a bursa between the acromion and rotator cuff and is narrowed in the setting of impingement. The long head of the biceps tendon runs through the bicipital groove and is a common source of anterior shoulder pain.

History

Age is a useful starting point: rotator cuff disease increases with age and is more common after 40, while instability is more typical in younger patients. The mechanism of injury should be explored, including overhead activity, a fall on an outstretched hand, a direct blow, or insidious onset without trauma. Pain location helps narrow the differential. Lateral deltoid pain suggests rotator cuff pathology, anterior pain points toward biceps or AC joint disease, pain at the top of the shoulder implicates the AC joint, and pain radiating to the neck and trapezius region raises concern for cervical referred pain. Night pain, particularly an inability to sleep on the affected side, is suggestive of rotator cuff pathology. It is important to distinguish true weakness from pain-limited weakness. Instability symptoms such as the sensation of the shoulder slipping out of place should be assessed, along with the patient's occupational and sport demands. Red flags include a history of cancer, constitutional symptoms, and trauma with deformity.

Physical Examination

Inspection and Range of Motion

Inspection should evaluate for atrophy of the supraspinatus or infraspinatus fossae, which suggests a chronic rotator cuff tear. Active range of motion includes forward flexion, abduction, external rotation, and internal rotation (hand behind the back). If passive range of motion exceeds active range, the finding suggests rotator cuff weakness, whereas limitation of passive range of motion as well points toward adhesive capsulitis or arthritis. A painful arc between 60 and 120 degrees of abduction is characteristic of impingement.

Rotator Cuff Tests

The Neer impingement sign is performed by stabilizing the scapula and passively forward flexing the arm; pain suggests impingement. The Hawkins-Kennedy test positions the shoulder and elbow at 90 degrees and internally rotates the forearm, with pain again indicating impingement. The empty can test (Jobe test) places the arms at 90 degrees of abduction and 30 degrees of forward flexion with the thumbs pointing down; weakness in this position suggests a supraspinatus tear. The external rotation lag sign is performed by positioning the arm in external rotation and asking the patient to maintain the position; inability to do so suggests an infraspinatus tear. The lift-off test (Gerber test) asks the patient to place a hand behind the back and push away; weakness suggests a subscapularis tear. The belly press test has the patient press a hand against the belly with the elbow forward; inability to maintain the elbow position also suggests subscapularis pathology. The drop arm test passively abducts the arm to 90 degrees and asks the patient to slowly lower it; inability to do so suggests a large rotator cuff tear.

Biceps Tendon Tests

The Speed test involves resisted forward flexion with the elbow extended and the forearm supinated, with pain in the bicipital groove being a positive finding. The Yergason test resists supination with the elbow at 90 degrees, again looking for pain in the bicipital groove.

AC Joint Tests

The cross-body adduction test adducts the arm across the body; pain at the AC joint is positive. Direct palpation over the AC joint evaluates for tenderness. The O'Brien test (active compression test) positions the arm at 90 degrees of forward flexion and 10 degrees of adduction and resists downward force, first with the thumb down (pain suggests AC joint pathology) and then with the thumb up (pain suggests a labral tear).

Instability Tests

The apprehension test abducts and externally rotates the shoulder; a positive result occurs when the patient becomes apprehensive. The relocation test applies a posterior force on the humeral head to relieve apprehension, confirming anterior instability. The sulcus sign applies downward traction on the arm; more than 2 cm of inferior subluxation suggests multidirectional instability.

Cervical Spine Screen

A cervical spine screen should include neck range of motion and the Spurling test (axial load with lateral flexion and extension). C5 radiculopathy can mimic shoulder pathology, causing deltoid weakness and lateral arm pain.

Imaging

X-Ray (First-Line)

Standard views include AP, scapular Y, and axillary lateral views. Findings to look for include superior migration of the humeral head (suggesting a large rotator cuff tear), AC joint arthritis, calcific tendinitis, fractures, and dislocations.

Ultrasound

Ultrasound is operator-dependent but highly accurate for rotator cuff tears in experienced hands. Its advantages include dynamic assessment, no radiation exposure, lower cost than MRI, and the ability to guide injections. It can detect full-thickness and partial-thickness tears, bursitis, and effusions.

MRI

MRI is the gold standard for soft tissue evaluation. It is indicated when there is a suspected rotator cuff tear in a surgical candidate, a labral tear, failure of conservative treatment beyond six weeks, or clinical uncertainty. MR arthrography is superior for labral tears and partial articular-sided rotator cuff tears.

Common Conditions

Rotator Cuff Tendinopathy/Impingement

Rotator cuff tendinopathy is the most common cause of shoulder pain in adults over 40 and exists on a spectrum from tendinopathy to partial tear to full-thickness tear. Patients typically report pain with overhead activities, night pain, and a painful arc. Management begins with activity modification and relative rest, followed by a physical therapy program lasting 6 to 12 weeks that emphasizes rotator cuff and scapular stabilizer strengthening, stretching, and posture correction. NSAIDs (oral or topical) are used for pain control. A subacromial corticosteroid injection provides short-term relief, with a maximum of three injections per year. Surgical referral is appropriate for full-thickness tears failing conservative treatment, especially in younger active patients, or for acute traumatic tears.

Rotator Cuff Tears

Partial-thickness tears are typically managed conservatively, following the same approach as tendinopathy. Full-thickness tears may also be managed conservatively in older, lower-demand patients who maintain good function. Acute traumatic tears in young patients warrant early surgical referral, as outcomes are better with earlier repair. Massive tears exceeding 5 cm or involving two or more tendons may require surgical repair, superior capsular reconstruction, or reverse total shoulder arthroplasty.

Adhesive Capsulitis (Frozen Shoulder)

Adhesive capsulitis is distinguished from rotator cuff pathology by a global loss of both active and passive range of motion, with external rotation being the most affected movement. Risk factors include diabetes (prevalence of 10 to 20%), thyroid disease, post-surgical immobilization, female sex, and age 40 to 60. The condition progresses through three stages: the freezing stage (painful, lasting 2 to 9 months), the frozen stage (stiffness predominates, lasting 4 to 12 months), and the thawing stage (gradual improvement, lasting 5 to 24 months). Management includes physical therapy with gentle range-of-motion exercises (avoiding aggressive stretching during the freezing phase), NSAIDs and analgesics, and intra-articular corticosteroid injection (most effective during the freezing stage). Hydrodilatation, which involves injection of saline and steroid to distend the capsule, is another option. Surgical options for refractory cases include manipulation under anesthesia and arthroscopic capsular release. Most cases resolve within 1 to 3 years, though up to 40% may have residual stiffness.

AC Joint Pathology

AC joint arthritis is common in weight lifters and laborers and presents with tenderness over the AC joint and a positive cross-body adduction test. AC joint separation (acromioclavicular sprain) is classified into Types I through VI. Type I is a sprain without displacement managed conservatively. Type II involves a torn AC ligament with intact coracoclavicular ligaments and a widened AC joint, also managed conservatively. Type III involves both AC and coracoclavicular ligament disruption with superior clavicle displacement; management is debated between conservative and surgical approaches. Types IV through VI require surgery. Treatment options include activity modification, ice, NSAIDs, and AC joint corticosteroid injection, with resection arthroplasty (distal clavicle excision) reserved for refractory arthritis.

Calcific Tendinitis

Calcific tendinitis involves calcium hydroxyapatite deposits in rotator cuff tendons, usually the supraspinatus. It is most common in women aged 30 to 60. The condition causes acute severe pain during the resorptive phase and may mimic septic arthritis. Calcium deposits are visible on X-ray. Treatment includes NSAIDs, subacromial corticosteroid injection, ultrasound-guided barbotage (needle aspiration of calcium), and extracorporeal shockwave therapy. Most deposits resolve spontaneously.

Glenohumeral Instability

Anterior instability is the most common form (95%) and typically occurs through an abduction plus external rotation mechanism. Younger patients are more likely to experience recurrent instability, with up to 90% risk of re-dislocation if the first episode occurs before age 20. A Bankart lesion is an anterior-inferior labral tear commonly associated with anterior dislocation, while a Hill-Sachs lesion is a posterolateral humeral head compression fracture. Management involves reduction, immobilization with a sling for comfort, and physical therapy with a strengthening program. Surgical referral is indicated for recurrent instability, young athletes, and significant bony lesions.

Biceps Tendinopathy

Biceps tendinopathy causes anterior shoulder pain in the bicipital groove and often coexists with rotator cuff pathology. Treatment includes activity modification, NSAIDs, and physical therapy, with biceps tendon sheath injection for persistent cases and tenodesis or tenotomy for refractory disease.

Subacromial Injection Technique

The patient is seated with the arm at the side in slight internal rotation. The landmark for the lateral approach is 1 cm inferior and medial to the posterolateral corner of the acromion. The needle is directed medially and slightly superiorly into the subacromial space. The injection consists of 1 mL of triamcinolone (40 mg) mixed with 4 to 5 mL of lidocaine 1%. Ultrasound guidance improves accuracy. After injection, the patient should avoid overhead activity for 48 hours, and the response should be assessed at 2 to 4 weeks.

<image>A comprehensive shoulder examination flowchart showing the systematic approach from inspection and ROM assessment through specific provocative tests organized by suspected pathology (rotator cuff impingement tests, rotator cuff tear tests, biceps tests, AC joint tests, instability tests, cervical screen), with positive test findings linked to the most likely diagnosis.</image>

<image>An anatomical diagram of the rotator cuff showing the four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) with their origins, insertions, and actions, the subacromial space with bursa, the AC joint, and the long head of biceps tendon, with annotations showing common sites of pathology and the corresponding physical exam tests for each structure.</image>

<image>A management algorithm for shoulder pain in primary care showing the initial evaluation pathway from history and physical exam through imaging decision (X-ray first, then ultrasound or MRI based on clinical suspicion), conservative treatment timeline (6-12 weeks of PT, NSAIDs, injection), and criteria for orthopedic referral (acute traumatic tear, failed conservative management, recurrent instability, full-thickness tear in active patient).</image>

Clinical Pearls

The single most important distinction in shoulder evaluation is whether passive range of motion is preserved: limited passive ROM suggests adhesive capsulitis or glenohumeral arthritis, while preserved passive ROM with painful or weak active ROM suggests rotator cuff pathology. Night pain severe enough to disrupt sleep is characteristic of rotator cuff disease and helps differentiate it from other causes of shoulder pain. Subacromial decompression surgery has been shown to be no better than sham surgery in multiple RCTs (CSAW, FIMPACT trials), so conservative treatment should be exhausted before considering surgical referral for impingement. Physical therapy focusing on rotator cuff strengthening and scapular stabilization is the foundation of treatment for most shoulder conditions and should be prescribed for a minimum of 6 to 12 weeks before considering treatment failure. A positive drop arm test suggests a large or complete rotator cuff tear and warrants imaging and potential surgical referral. In frozen shoulder, external rotation is the most restricted motion, and aggressive stretching during the freezing phase may worsen pain and should be avoided. Corticosteroid injection provides short-term pain relief lasting weeks but does not change the natural history of rotator cuff tendinopathy; it should be used as a bridge to facilitate physical therapy participation. Young patients under 20 years with a first-time anterior shoulder dislocation have up to 90% risk of recurrence, and early surgical referral should be considered, especially in athletes.

References

• Diercks R et al. Guideline for Diagnosis and Treatment of Subacromial Pain Syndrome. Acta Orthop. 2014
• Beard DJ et al. Arthroscopic Subacromial Decompression vs. Sham (CSAW Trial). Lancet. 2018
• Paavola M et al. Subacromial Decompression vs. Diagnostic Arthroscopy (FIMPACT). BMJ. 2018
• Kelley MJ et al. Shoulder Pain and Mobility Deficits: Adhesive Capsulitis. J Orthop Sports Phys Ther. 2013
• Burbank KM et al. Chronic Shoulder Pain: Evaluation and Diagnosis. Am Fam Physician. 2008

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