Musculoskeletal

Shoulder pain: rotator cuff, impingement, frozen shoulder

Clinical Overview and When to Suspect Shoulder Pain Syndromes

— Subacromial impingement/rotator cuff tendinopathy: painful arc, worse overhead, often chronic and activity-related

— Rotator cuff tear (partial or full-thickness): weakness > pain, especially abduction/external rotation; acute traumatic vs degenerative

— Adhesive capsulitis ("frozen shoulder"): global loss of both active and passive range of motion, insidious onset, classically in 40–60 yo women with diabetes or thyroid disease

— Overhead worker, painter, swimmer with insidious anterior/lateral shoulder pain → impingement

— Fall on outstretched arm or sudden lifting injury in patient >40 with new weakness → acute cuff tear

— Diabetic woman, age 40–60, with progressive stiffness "I can't reach my back pocket or bra strap" → frozen shoulder

— Shoulder pain with night pain, inability to lie on affected side → cuff pathology (very common feature)

— Pain at rest, fevers, weight loss → infection, malignancy

— Neurologic deficit, radicular distribution → cervical radiculopathy (C5–C6)

— Trauma with deformity → fracture, dislocation

— Left shoulder pain with exertion or diaphoresis → rule out ACS before MSK workup

Shoulder pain is one of the top 3 musculoskeletal complaints in US primary care, with lifetime prevalence ~70%. The vast majority is soft tissue (rotator cuff, subacromial bursitis, adhesive capsulitis), not glenohumeral arthritis or referred pain.

Three syndromes dominate the differential in adults:

When to suspect each pattern:

Red flags mandating broader workup:

Board pearl: A patient with shoulder pain who cannot actively abduct but you can passively raise the arm and they can hold it (drop arm negative) suggests cuff weakness without full tear; complete inability to maintain abduction = drop arm sign = likely full-thickness supraspinatus tear.

Step 3 framing emphasizes outpatient triage: most cases are managed conservatively for 6–12 weeks before imaging or referral.

Presentation Patterns and Key History

— Gradual onset over weeks–months; lateral deltoid pain

— Worse with overhead activity (combing hair, reaching upper shelf, throwing)

— Painful arc 60°–120° of abduction

— Often bilateral in chronic overhead workers

— Acute: fall, sudden traction, lifting heavy object; immediate weakness

— Chronic/degenerative: age >60, insidious weakness, often after minor trauma in already-tendinopathic shoulder

— Night pain unrelieved by position change is a classic complaint

— Difficulty with activities of daily living (washing hair, putting on jacket)

— Three phases: freezing (painful, 2–9 mo) → frozen (stiff, less painful, 4–12 mo) → thawing (gradual ROM return, 5–24 mo)

— Loss of external rotation with arm at side is the earliest and most specific finding

— Strong associations: diabetes (5x risk, often bilateral), hypothyroidism, prolonged immobilization, post-stroke, post-MI, breast/thoracic surgery

History drives the diagnosis more than imaging in shoulder pain. Anchor your questions around: onset, mechanism, location, aggravators, night symptoms, prior episodes, occupation/sport, and systemic disease.

Rotator cuff tendinopathy / impingement:

Rotator cuff tear:

Adhesive capsulitis (frozen shoulder):

Calcific tendinitis: acute, severe, "worst pain of my life" shoulder; calcium hydroxyapatite deposit; often mimics septic joint

Biceps tendinopathy: anterior shoulder pain with lifting, often coexists with cuff disease

AC joint pathology: pain localized to top of shoulder, worse with cross-body adduction; history of direct fall on point of shoulder

Key distinction: Impingement and partial cuff tears typically have pain > weakness; full-thickness tears have weakness > pain; frozen shoulder has stiffness > weakness with global ROM loss.

Ask about hand dominance, occupation (overhead labor, dental hygienist, hairstylist), and prior steroid injections — frequency matters for management decisions.

Physical Exam Findings

— Measure active then passive ROM in forward flexion, abduction, external rotation (arm at side), internal rotation (thumb up back)

— Cuff disease: active < passive (weakness/pain limits active motion, passive preserved)

— Frozen shoulder: active = passive, both reduced; external rotation loss is hallmark

— Glenohumeral OA: active = passive reduced, often crepitus

— Neer: passive forward flexion with scapula stabilized → pain

— Hawkins-Kennedy: 90° flexion, elbow bent, internal rotation → pain

— Empty can (Jobe): supraspinatus — arm at 90° abduction, 30° forward, thumb down; resist downward pressure

— External rotation lag at side: infraspinatus

— Lift-off / belly-press: subscapularis

— Drop arm test: passively abduct to 90°, ask patient to slowly lower — sudden drop = full-thickness supraspinatus tear (high specificity)

— Speed's: resisted forward flexion with elbow extended, supinated → biceps tendinopathy

— O'Brien's active compression: SLAP lesion

Inspection: muscle atrophy of supraspinatus/infraspinatus fossae suggests chronic cuff tear or suprascapular nerve entrapment; deformity suggests dislocation or AC separation.

Range of motion — the single most useful discriminator:

Provocative tests for impingement:

Rotator cuff strength testing:

Labral / biceps tests:

AC joint: cross-body adduction test, direct palpation tenderness

Cervical screen is mandatory: Spurling's maneuver, neck ROM, dermatomal sensation, reflexes — shoulder pain may be C5–C6 radiculopathy.

Board pearl: External rotation lag sign (inability to hold passively externally rotated arm) has the highest specificity for full-thickness infraspinatus tear and should prompt MRI/orthopedic referral even before imaging.

Document neurovascular exam: axillary nerve sensation over lateral deltoid, distal pulses — especially after trauma or dislocation reduction.

Diagnostic Workup — Initial Imaging

— Trauma with suspected fracture or dislocation

— Suspected full-thickness tear (drop arm, significant weakness, age >60 with acute event)

— Suspected septic arthritis (fever, erythema, severe pain at rest)

— Failure of 6–12 weeks conservative therapy

— Pre-operative planning

— Standard series: AP in internal and external rotation, scapular Y (outlet) view, axillary view

— Findings:

— Subacromial spur, type III (hooked) acromion → impingement

— High-riding humeral head (acromiohumeral interval <7 mm) → chronic massive cuff tear

— Calcium deposit in cuff → calcific tendinitis

— Glenohumeral joint space narrowing, osteophytes → OA

— Hill-Sachs lesion, bony Bankart → recurrent dislocation

— In frozen shoulder, plain films are typically normal — useful mainly to exclude other causes

— Operator-dependent; sensitivity/specificity ~90% in experienced hands for full-thickness tears

— Allows dynamic assessment and guided injection

— CBC, ESR, CRP if infection or inflammatory arthritis suspected

— HbA1c and TSH in suspected frozen shoulder — addressing undiagnosed diabetes/thyroid disease is part of comprehensive management

— Joint aspiration with cell count, Gram stain, crystals if monoarticular effusion + fever

Most shoulder pain does NOT require initial imaging. USPSTF and AAFP support a trial of conservative therapy for 6 weeks in atraumatic, non-red-flag cases before imaging.

When to image at presentation:

Plain radiographs are the first-line imaging study:

Ultrasound: increasingly first-line in primary care/sports medicine for cuff tears

Labs: not routinely indicated. Consider:

ECG if left shoulder pain with cardiac risk factors or exertional component — never miss ACS masquerading as MSK pain.

Step 3 management: In a 55-year-old diabetic woman with insidious shoulder stiffness, order plain radiographs (likely normal), check HbA1c and TSH, and start a structured PT program — MRI is not initially indicated for frozen shoulder.

Diagnostic Workup — Advanced or Confirmatory Studies

— Indications: suspected full-thickness cuff tear, failure of conservative therapy at 6–12 weeks, pre-surgical planning, suspected labral tear, occult fracture, suspected mass

— Identifies tear size, location, retraction, muscle atrophy, and fatty infiltration (Goutallier grade) — grade ≥3 fatty infiltration predicts poor surgical outcome and may shift management toward conservative care

— Detects partial-thickness tears, bursitis, biceps pathology

— Best for bony detail: complex fractures, glenoid bone loss in recurrent instability, surgical planning for shoulder arthroplasty

— CT arthrography for patients who cannot have MRI

— Pain relief after lidocaine injection that allows full ROM and strength → impingement/bursitis

— Persistent weakness despite pain relief → structural cuff tear

— This is the classic Neer impingement test and remains highly useful clinically

MRI shoulder is the gold standard for soft tissue pathology:

MR arthrography: improves sensitivity for labral tears (SLAP, Bankart) and partial-thickness articular-sided cuff tears; useful in young athletes with instability or post-dislocation evaluation

CT shoulder:

Diagnostic ultrasound: used in-office for guided injections, dynamic impingement assessment, and confirmation of cuff tears

EMG/nerve conduction: consider when cervical radiculopathy, brachial plexopathy, or suprascapular nerve entrapment (parsonage-turner, paralabral cyst) is suspected — particularly if isolated infraspinatus atrophy with weakness

Diagnostic subacromial injection (lidocaine):

Adhesive capsulitis is a clinical diagnosis — MRI may show thickened coracohumeral ligament and axillary recess capsule but is not required.

Board pearl: Always interpret MRI findings in clinical context — asymptomatic rotator cuff tears are present in ~25% of patients over 60 and ~50% over 70. A tear on MRI does not automatically mean surgery; the clinical exam drives management, not the imaging report.

Document shared decision-making when ordering advanced imaging — cost, incidental findings, and impact on management should be discussed.

Risk Stratification and First-Line Management Logic

— Tendinopathy / impingement / partial tear / frozen shoulder → conservative first (PT, NSAIDs, activity modification, ± injection) for 6–12 weeks minimum

— Acute traumatic full-thickness tear in patient <65 with high functional demand → early orthopedic referral for surgical consideration within 3–6 weeks (delays >6 months worsen outcomes due to retraction and fatty infiltration)

— Chronic degenerative full-thickness tear in older, lower-demand patient → trial conservative therapy first; surgery if PT fails

— Massive irreparable tear with pseudoparalysis → consider reverse total shoulder arthroplasty

— Activity modification: avoid overhead activity, heavy lifting; do NOT immobilize for prolonged periods (worsens stiffness, especially in frozen shoulder)

— Structured physical therapy: the single most evidence-based intervention for all three syndromes

— Cuff strengthening, scapular stabilization for impingement

— Aggressive stretching and ROM for frozen shoulder (gentle, daily)

— NSAIDs: 2–4 week course for pain control

— Ice/heat, postural correction, ergonomic adjustments

— Self-limited but prolonged (1–3 years)

— Intra-articular steroid injection early in the painful "freezing" phase improves pain and shortens course

— Treat underlying diabetes/thyroid disease

— Acute full-thickness tear in active patient

— Failure of 3–6 months conservative therapy

— Recurrent instability with structural lesions

— Refractory frozen shoulder >12 months despite PT/injection (consider manipulation under anesthesia or arthroscopic capsular release)

Stratify by tear status, functional demand, and chronicity:

Conservative management cornerstones:

Frozen shoulder-specific logic:

Indications for surgical referral:

Step 3 management: For a 50-year-old with subacromial impingement: prescribe 6 weeks of structured PT, NSAIDs PRN, activity modification, return visit at 6 weeks — not immediate MRI or orthopedic referral.

Pharmacotherapy — First-Line Drug Regimen

— Ibuprofen 400–800 mg TID with food, or naproxen 500 mg BID, for 2–4 weeks

— Topical diclofenac gel for patients with GI, renal, or cardiovascular risk

— Check renal function, blood pressure, GI risk before prescribing

— Avoid in CKD stage ≥3, active PUD, heart failure, on anticoagulants without PPI cover

— Triamcinolone 40 mg + 1% lidocaine 3–5 mL is a typical formulation

— Subacromial injection for impingement, bursitis, partial cuff tear

— Glenohumeral (intra-articular) injection for frozen shoulder and glenohumeral OA — best benefit in early freezing phase

— Provides short-term pain relief (weeks to months); enables PT participation

— Limit to 3 injections per joint per year; repeated injections can weaken tendons and damage cartilage

— Avoid injection within 3 months of planned arthroscopy (infection risk) and into the cuff tendon itself

— Counsel diabetics about transient hyperglycemia for 3–7 days post-injection

NSAIDs are first-line for pain and inflammation:

Acetaminophen 650–1000 mg QID up to 3 g/day: useful adjunct or alternative when NSAIDs contraindicated

Corticosteroid injections (subacromial or glenohumeral):

Hydrodilatation / capsular distension for frozen shoulder: injection of large volume of saline + steroid + anesthetic to mechanically stretch capsule — modest evidence

Oral corticosteroids: short course (e.g., prednisone 30 mg taper over 3 weeks) considered in severe early-phase frozen shoulder unresponsive to injection; weigh against glycemic effects in diabetics

Opioids: avoid for chronic MSK shoulder pain; limited role for acute post-traumatic or post-operative pain only, with short duration and PDMP check

Adjuncts: muscle relaxants generally not indicated; gabapentin/duloxetine reserved for neuropathic overlay or concurrent chronic pain syndrome

Board pearl: A diabetic patient receiving a steroid shoulder injection should be counseled to monitor fingersticks for 3–7 days — glucose can rise 50–100 mg/dL; adjust insulin if needed but do not withhold the injection if otherwise indicated.

Procedures and Surgical Management

— Improve accuracy vs landmark-based, especially for glenohumeral and biceps tendon sheath injections

— Standard practice in sports medicine and interventional pain

— Arthroscopic subacromial decompression for refractory impingement: increasingly questioned — recent RCTs (CSAW trial) show no benefit over sham or PT alone for isolated impingement; rarely indicated in absence of structural tear

— Arthroscopic rotator cuff repair: for full-thickness tears in symptomatic patients with adequate tissue quality

— Best outcomes when performed within 3–6 months of acute tear

— Postop: sling 4–6 weeks, passive ROM, then progressive PT over 4–6 months; full recovery 6–12 months

— Reverse total shoulder arthroplasty: for massive irreparable cuff tears with pseudoparalysis or cuff tear arthropathy, typically in patients >65

— Tendon transfers (latissimus, lower trapezius): for younger patients with irreparable tears

— Intra-articular corticosteroid injection: first-line procedural intervention

— Hydrodilatation: capsular distension under imaging

— Manipulation under anesthesia (MUA): for refractory cases >6–12 months; risk of humeral fracture, especially in osteoporotic patients

— Arthroscopic capsular release: definitive procedure for recalcitrant frozen shoulder

— Hold anticoagulation per joint injection protocol (often continue for minor injections; individualize)

— Document informed consent: bleeding, infection, post-injection flare (10%), tendon rupture, skin atrophy/depigmentation

— Aseptic technique; chlorhexidine prep

Image-guided injections (ultrasound or fluoroscopy):

Surgical options for rotator cuff disease:

Frozen shoulder procedures:

Calcific tendinitis: ultrasound-guided barbotage (needle lavage) ± steroid injection is highly effective

Pre-procedure considerations:

CCS pearl: For a 55-yo with acute traumatic full-thickness supraspinatus tear after a fall, orders should include: shoulder XR → MRI → orthopedic referral within 1–2 weeks, sling for comfort, NSAIDs, do NOT delay referral beyond 6 weeks.

Special Populations — Elderly and Renal/Hepatic Impairment

— High prevalence of asymptomatic rotator cuff tears (>50% over age 70); imaging findings often do not correlate with symptoms

— Functional demand assessment is critical — surgical repair offers less benefit in low-demand patients

— Fall risk assessment is essential; shoulder pain limits ability to use assistive devices and break a fall

— Polypharmacy considerations before NSAID prescribing: anticoagulants, antiplatelets, ACE inhibitors, diuretics

— Increased risk of GI bleeding, AKI, hypertension, heart failure exacerbation

— Use lowest effective dose for shortest duration

— Add PPI if age >65 and any GI risk factor or on antiplatelet/anticoagulant

— Prefer topical NSAIDs or acetaminophen first-line per Beers criteria

— Avoid systemic NSAIDs if eGFR <30; use with caution and monitoring at eGFR 30–59

— Acetaminophen and topical agents preferred

— Steroid injections do not require dose adjustment but monitor BP and glucose

— Acetaminophen: cap at 2 g/day in significant liver disease; avoid in active alcohol use disorder

— NSAIDs: avoid in cirrhosis (risk of variceal bleed, hepatorenal syndrome)

— Caution with manipulation under anesthesia — humeral fracture risk

— DEXA screening per USPSTF for women ≥65 and high-risk men

— Frozen shoulder more common in postmenopausal women — assess for fracture risk

— Limits ability to participate in PT; involve family/caregivers in home exercise programs

— Pain may present as agitation or behavioral change

Elderly patients (≥65):

NSAID precautions in elderly:

Renal impairment:

Hepatic impairment:

Osteoporosis:

Cognitive impairment:

Step 3 management: In a 78-year-old with degenerative supraspinatus tear, CKD stage 3, on warfarin: avoid systemic NSAIDs, use topical diclofenac + acetaminophen 2–3 g/day, prioritize PT, consider ultrasound-guided injection (hold/manage anticoagulation per protocol), and discuss realistic functional goals rather than reflex surgical referral.

Special Populations — Pregnancy, Athletes, and Occupational

— Avoid NSAIDs after 20 weeks gestation (FDA 2020 warning: oligohydramnios, fetal renal dysfunction) and especially after 30 weeks (premature ductus arteriosus closure)

— Acetaminophen is preferred analgesic; use lowest effective dose

— Local corticosteroid injections generally considered safe in pregnancy if clearly indicated; minimal systemic absorption

— Prioritize PT, postural modification (altered biomechanics from breast enlargement, lordosis)

— Topical agents: topical NSAIDs avoided in 3rd trimester; lidocaine patches acceptable

— Suspect instability, labral tears (SLAP), Little League shoulder (proximal humeral epiphysiolysis in overhead throwers)

— Rotator cuff tears are uncommon under age 30 unless traumatic

— Multidirectional instability in patients with hypermobility (Ehlers-Danlos, generalized laxity) → conservative scapular stabilization program before considering surgery

— Return-to-play decisions require sports medicine input and graduated functional progression

— Internal impingement (posterior superior cuff against posterior glenoid in late cocking)

— GIRD (glenohumeral internal rotation deficit) — treat with sleeper stretches

— Off-season strengthening, pitch count limits

— Painters, electricians, dental hygienists, assembly workers, hairdressers

— Document work-relatedness for workers' compensation; recommend ergonomic evaluation

— Modified duty during recovery improves outcomes vs full work absence

— Consider OSHA reporting obligations for work-related musculoskeletal disorders

— 5x risk of frozen shoulder; often bilateral and more refractory

— Optimize glycemic control as part of treatment

— Counsel on transient hyperglycemia after steroid injection

Pregnancy:

Adolescents/young athletes:

Overhead throwing athletes:

Occupational shoulder pain:

Diabetic patients:

Board pearl: A 16-year-old little league pitcher with progressive shoulder pain and tenderness over the proximal humerus has Little League shoulder (proximal humeral physeal stress injury) — treat with 3 months of rest from throwing and pitch count reform, not immediate MRI or surgery.

Complications and Adverse Outcomes

— Progression of partial to full-thickness cuff tear in untreated tendinopathy (~30–50% over years)

— Cuff tear arthropathy: chronic massive tear → superior humeral migration → glenohumeral arthritis → pseudoparalysis

— Chronic pain syndrome / kinesiophobia: prolonged disuse, depression, opioid dependence

— Persistent ADL limitation: difficulty with dressing, hygiene, driving — particularly in elderly leading to loss of independence

— Adhesive capsulitis can develop secondary to prolonged immobilization of any shoulder injury — early mobilization is preventive

— Post-injection flare (10%, 24–48 hr, self-limited)

— Skin atrophy, hypopigmentation (especially in darker skin tones — counsel)

— Tendon weakening/rupture with repeated injections

— Transient hyperglycemia

— Infection (rare, <0.01%) — septic arthritis is a surgical emergency

— Facial flushing, menstrual irregularity

— Re-tear after cuff repair: 20–40% (size-dependent; massive tears highest)

— Stiffness/postoperative frozen shoulder (5–10%)

— Infection, particularly Cutibacterium acnes (indolent, low-grade) — characteristic of shoulder surgery

— Nerve injury (axillary, suprascapular)

— Hardware failure

— Humeral shaft fracture during MUA

— Persistent stiffness despite intervention (~10%)

— Bilateral involvement in 20–30% (often metachronous)

— Septic shoulder mistaken for calcific tendinitis

— Pancoast tumor presenting as shoulder/arm pain with Horner syndrome

— Referred cardiac pain in left shoulder

— Cervical radiculopathy mistaken for cuff pathology

Complications of untreated/undertreated shoulder pain:

Complications of NSAIDs: GI bleed, AKI, hypertension, heart failure exacerbation, MI/stroke risk with chronic use

Complications of corticosteroid injections:

Surgical complications:

Frozen shoulder complications:

Missed diagnoses to avoid:

Key distinction: Post-injection flare presents within 24–48 hours and resolves spontaneously; septic arthritis typically presents at 2–7 days post-injection with worsening pain, fever, erythema, and elevated inflammatory markers — requires emergent aspiration and antibiotics.

When to Escalate Care — Referral and Inpatient Triage

— Septic arthritis: fever, severe pain, effusion, elevated CRP/ESR, positive synovial fluid → IV antibiotics + surgical washout

— Open fracture or fracture-dislocation requiring urgent operative fixation

— Neurovascular compromise post-dislocation (axillary artery, brachial plexus injury)

— Pancoast tumor or other malignancy presenting with shoulder pain

— Acute dislocation requiring reduction

— Suspected fracture

— Suspected septic joint

— Severe trauma with neurologic deficit

— Suspected ACS or aortic dissection presenting as shoulder pain

— Acute traumatic full-thickness rotator cuff tear in active patient

— Recurrent shoulder dislocation

— Suspected glenohumeral septic arthritis (after initial ED management)

— Persistent neurologic deficit

— Failure of structured conservative therapy

— Imaging-confirmed structural lesion amenable to surgery

— Refractory frozen shoulder >6–12 months despite PT and injection

— Recurrent calcific tendinitis

— Endocrinology: refractory frozen shoulder with poor diabetic control

— Rheumatology: suspected inflammatory arthritis (polymyalgia rheumatica, RA, gout, pseudogout)

— Neurology / EMG: suspected cervical radiculopathy, brachial plexopathy, suprascapular nerve entrapment

— Pain management: chronic pain with functional limitation despite optimal MSK care

— Physical therapy: nearly universal referral — the cornerstone of conservative care

Most shoulder pain is managed entirely in the outpatient setting. Inpatient admission is rare and reserved for:

Same-day ED referral:

Urgent orthopedic referral (within 1–2 weeks):

Routine orthopedic / sports medicine referral (4–12 weeks):

Other consults:

CCS pearl: For a patient post-injection with fever, worsening shoulder pain at day 3, and erythema, orders should include: CBC, CRP, ESR, blood cultures, emergent shoulder aspiration with Gram stain/culture/cell count, IV vancomycin + ceftriaxone empirically, and orthopedic consult for likely operative washout. Do not delay for MRI.

Key Differentials — Same-Category (Musculoskeletal) Causes

— Tendinopathy → partial-thickness tear → full-thickness tear → massive tear → cuff tear arthropathy

— Distinguished by strength testing, ROM pattern, drop arm sign, and imaging

— Acute severe pain, often nocturnal onset

— Calcium hydroxyapatite deposition in cuff (most often supraspinatus)

— Radiographic calcific deposit

— Treated with NSAIDs, ultrasound-guided barbotage, steroid injection

— Long head biceps tendinopathy: anterior shoulder pain, positive Speed's

— Proximal biceps rupture: "Popeye deformity" with bulging distal biceps muscle belly — typically older patients, conservative management; cosmesis only mildly affected, function preserved

— Osteoarthritis or post-traumatic separation

— Pain at superior shoulder, positive cross-body adduction

— Treatment: NSAIDs, AC joint injection, rarely surgical excision of distal clavicle

— Older patients, deep shoulder pain, mechanical symptoms, ROM loss (both active and passive)

— Radiographic joint space narrowing, osteophytes

— Treatment: PT, NSAIDs, injection; total shoulder arthroplasty for refractory cases

— Younger patients, often athletes

— Mechanical symptoms (clicking, catching), instability

— MR arthrography for diagnosis

Rotator cuff disease spectrum:

Subacromial bursitis: often coexists with impingement; relief with subacromial lidocaine injection is diagnostic

Calcific tendinitis:

Biceps tendinopathy / rupture:

AC joint pathology:

Glenohumeral osteoarthritis:

Labral tears (SLAP, Bankart):

Shoulder instability / dislocation: anterior (95%), posterior (associated with seizures, electrical injury), recurrent → consider surgical stabilization

Adhesive capsulitis: clinical diagnosis, global ROM loss

Scapulothoracic dysfunction / dyskinesis: poor scapular control causing secondary impingement; addressed in PT

Key distinction: Glenohumeral OA and adhesive capsulitis both cause loss of active AND passive ROM, but OA has radiographic joint space narrowing and crepitus while frozen shoulder has normal radiographs and a characteristic phasic clinical course.

Key Differentials — Other-Category (Non-MSK) Causes

— Pain radiating from neck to shoulder/arm, often dermatomal

— Positive Spurling's, reduced reflexes, sensory changes

— Neck movement provokes pain more than shoulder movement

— MRI cervical spine if persistent or with deficit

— Left shoulder, arm, or jaw pain with exertion, diaphoresis, dyspnea, nausea

— Always rule out in any patient with shoulder pain and cardiac risk factors, especially women, diabetics, elderly

— Obtain ECG and troponin liberally

— Pancoast tumor (superior sulcus): shoulder pain, Horner syndrome (ptosis, miosis, anhidrosis), C8/T1 distribution arm weakness — order CXR; CT chest if suspicious

— Pleural irritation, pneumothorax: referred shoulder pain via diaphragmatic involvement

— Subphrenic abscess, splenic rupture (Kehr's sign — left shoulder pain), hepatobiliary disease, perforated viscus

— Cholecystitis: right shoulder/scapular referred pain

— Hepatic abscess, hepatic capsular distension

— Polymyalgia rheumatica: bilateral shoulder/hip girdle pain and stiffness in patients >50, elevated ESR/CRP, dramatic response to low-dose prednisone; check for giant cell arteritis symptoms

— Rheumatoid arthritis, lupus, gout, pseudogout: polyarticular involvement, systemic features

— Fibromyalgia: widespread pain with tender points

— Acute severe shoulder pain → followed by weakness/atrophy

— Often post-viral or post-vaccination

— EMG diagnostic; mostly self-limited

Cervical radiculopathy (C5, C6, C7):

Cardiac ischemia / ACS:

Pulmonary causes:

Diaphragmatic irritation:

Hepatobiliary:

Aortic dissection: tearing chest pain radiating to back or shoulder, pulse differential, mediastinal widening

Herpes zoster: dermatomal pain preceding rash by 2–3 days; consider in unilateral shoulder pain with hyperesthesia

Inflammatory and systemic:

Brachial neuritis (Parsonage-Turner syndrome):

Complex regional pain syndrome (CRPS): post-injury or post-stroke, allodynia, vasomotor/sudomotor changes

Board pearl: In any patient >50 with bilateral shoulder/hip girdle stiffness, morning stiffness >45 minutes, and elevated ESR, suspect polymyalgia rheumatica, check for temporal arteritis symptoms (headache, jaw claudication, vision changes), and start prednisone 15 mg daily — dramatic response within days confirms the diagnosis.

Secondary Prevention and Long-Term Plan

— Workplace ergonomic evaluation for overhead workers; tool modification, work height adjustment

— Athlete-specific: pitch count limits, technique correction, off-season conditioning

— Avoid sustained overhead positions; take micro-breaks

— Continue rotator cuff strengthening and scapular stabilization exercises lifelong after recovery from cuff tendinopathy or repair

— Daily ROM stretching to prevent recurrent frozen shoulder, particularly in diabetics

— Posture: address forward head, rounded shoulder posture contributing to impingement

— Glycemic control (HbA1c <7%): reduces frozen shoulder risk and improves recovery

— Thyroid optimization

— Lipid management — emerging link between dyslipidemia and tendinopathy

— Smoking cessation: smoking impairs tendon healing and increases re-tear risk after cuff repair

— Weight management

— Avoid chronic NSAID use; intermittent use for flares with PPI cover as appropriate

— Calcium and vitamin D supplementation in postmenopausal women / elderly to reduce fracture risk

— Bisphosphonate therapy per DEXA findings — note: some controversy about effect on tendon healing, but should not be withheld for fracture prevention

— Disability documentation, FMLA when needed

— Vocational rehabilitation referral for workers unable to return to prior occupation

— Modified duty plans

— 6–12 months of structured rehab after cuff repair

— Return-to-work timelines: sedentary 2–6 weeks, light duty 3 months, heavy labor 4–6 months

— Lifelong exercise compliance reduces re-tear risk

— Screen for depression in chronic pain patients (PHQ-9)

— Address kinesiophobia and pain catastrophizing — refer to pain psychology if needed

Activity modification and ergonomics:

Maintenance exercise program:

Management of comorbidities:

Pharmacologic secondary prevention:

Vocational considerations:

Post-surgical long-term plan:

Mental health:

Step 3 management: A diabetic patient recovering from frozen shoulder needs: tight glycemic control (HbA1c goal <7%), daily home stretching program indefinitely, screening for contralateral involvement at each follow-up, and counseling that recurrence in the other shoulder occurs in 20–30%.

Follow-Up, Monitoring, and Rehab Counseling

— Initial visit: history, exam, conservative treatment plan, PT referral

— Re-evaluate at 6 weeks: assess response to PT, NSAIDs, activity modification

— If improving: continue program, follow up in 6 weeks

— If plateau or worsening: escalate (imaging, injection, specialist referral)

— At 3 months: if not significantly improved with optimal conservative care, MRI and orthopedic referral

— Post-injection: follow up at 4–6 weeks to assess durability of response

— Typically 6–12 weeks, 1–3 sessions/week + daily home exercise program

— Phase 1: pain control, ROM restoration

— Phase 2: strengthening (cuff, scapular stabilizers, posterior chain)

— Phase 3: functional/sport-specific training

— Patient adherence to home exercise program is the strongest predictor of outcome

— Sling 4–6 weeks

— Week 0–6: passive ROM only (codman pendulum, passive forward elevation)

— Week 6–12: active-assisted then active ROM

— Month 3–6: progressive strengthening

— Month 6–12: return to full activity

— Surgeon follow-up at 2 weeks, 6 weeks, 3 months, 6 months, 1 year

— Reassure regarding self-limited but prolonged course (1–3 years)

— Track ROM measurements at each visit; document external rotation progress

— Re-image only if atypical course or new findings

— New weakness, sensory deficits

— Constitutional symptoms (fever, weight loss, night sweats)

— Worsening pain unresponsive to escalation

— Failure to progress despite adherent PT

— Realistic timelines (months, not weeks)

— Active participation in home program is essential

— Pain during exercise is acceptable; sharp/severe pain is not

— Sleep posture: pillow under affected arm

Follow-up cadence in primary care:

Physical therapy program:

Post-surgical follow-up after cuff repair:

Frozen shoulder monitoring:

Red flags during follow-up requiring re-evaluation:

Patient counseling points:

CCS pearl: Schedule a 6-week follow-up for any shoulder pain patient started on conservative therapy. If not at goal, advance the workup — do not simply "continue current treatment" indefinitely without re-evaluation.

Ethical, Legal, and Patient Safety Considerations

— Document risks/benefits of injections: infection, post-injection flare, skin changes, tendon weakening, transient hyperglycemia

— For surgery: re-tear, infection (especially C. acnes), stiffness, nerve injury, anesthesia risks

— Discuss alternatives including continued conservative management

— Special consideration: counsel patients of color about steroid-induced skin hypopigmentation and atrophy at injection sites — historically under-disclosed

— Accurately characterize work-relatedness without overstating or understating

— Provide modified duty restrictions promptly

— Avoid disability "drift" — set rehabilitation goals with timelines

— Beware of secondary gain influencing presentation, but do not assume malingering

— Avoid chronic opioids for shoulder pain; CDC guidelines

— Check PDMP before any opioid prescription

— Naloxone co-prescription for high-risk patients

— Document non-pharmacologic and non-opioid attempts

— Post-discharge after shoulder surgery: ensure clear sling instructions, PT referral made and scheduled, pain medication reconciled, follow-up appointment booked before discharge

— Missed orthopedic follow-up after acute cuff tear → tendon retraction, irreparable tear, permanent disability — establish a safety-net call-back system

— Communicate test results: an MRI showing acute tear must be communicated within days, not weeks

— Shoulder injuries from suspected domestic violence, elder abuse, child abuse require reporting per state law

— Pattern injuries, inconsistent histories, delayed presentation are red flags

— Work-related musculoskeletal disorders may require OSHA reporting

— Patients in slings or with limited shoulder ROM should not drive; document counseling

— Some states require physician reporting of impaired drivers

— Access to PT may be limited by insurance and geography — provide home exercise program handouts for all patients

— Language-concordant patient education materials

Informed consent for procedures:

Workers' compensation and disability documentation:

Opioid prescribing safety:

Transition-of-care risks (high-yield Step 3 theme):

Mandatory reporting:

Driving safety:

Health equity:

Board pearl: A worker with shoulder injury and pending workers' comp claim still deserves evidence-based care; do not undertreat due to suspicion of secondary gain, and do not overtreat due to legal pressure — document findings objectively and treat the clinical condition.

High-Yield Associations and Rapid-Fire Clinical Facts

Painful arc (60°–120° abduction) → impingement / supraspinatus

Drop arm test positive → full-thickness supraspinatus tear

External rotation lag sign → infraspinatus full-thickness tear

Belly-press / lift-off → subscapularis tear

Loss of passive external rotation with arm at side → adhesive capsulitis (earliest finding)

Frozen shoulder triad of associations: diabetes, hypothyroidism, female 40–60

Bilateral frozen shoulder → suspect diabetes

Acute severe shoulder pain + radiographic calcific deposit → calcific tendinitis

Popeye deformity → proximal long head biceps rupture (older patient, conservative tx)

Posterior shoulder dislocation → think seizure or electrocution (rim sign / light bulb sign on XR)

Anterior dislocation → axillary nerve injury (deltoid weakness, lateral shoulder numbness)

Hill-Sachs lesion (humeral head) and Bankart lesion (anterior-inferior labrum) → recurrent anterior dislocation

High-riding humeral head on XR → chronic massive cuff tear

Acromiohumeral interval <7 mm → cuff tear arthropathy

Type III (hooked) acromion → predisposes to impingement

Goutallier grade ≥3 fatty infiltration → poor surgical outcome

Kehr's sign (left shoulder pain after trauma) → splenic rupture

Pancoast tumor: shoulder pain + Horner + arm weakness → CXR/CT chest

Polymyalgia rheumatica: bilateral shoulder/hip stiffness, age >50, ESR >40, prednisone response

Parsonage-Turner: acute pain → weakness, post-viral, EMG diagnostic

Little League shoulder: proximal humeral physeal injury, throwing kids

Cutibacterium acnes: indolent post-surgical shoulder infection — characteristic organism

CSAW trial: subacromial decompression no better than sham for isolated impingement

First-line for frozen shoulder pain: intra-articular steroid injection + PT

First-line for impingement: 6–12 weeks PT + NSAIDs + activity modification

Most accurate test for full-thickness tear: MRI (or experienced ultrasound)

Best initial imaging: plain radiographs (AP int/ext rotation, scapular Y, axillary)

Asymptomatic cuff tears: 25% over age 60, 50% over age 70

Board pearl: Shoulder pain in a patient >50 with rapid onset of stiffness, normal radiographs, and HbA1c of 9% — this is diabetic frozen shoulder until proven otherwise; treat aggressively with PT and intra-articular injection, and optimize glycemic control as part of musculoskeletal management.

Board Question Stem Patterns

Pattern 1 — Impingement: "45-yo painter, gradual right shoulder pain worse with overhead reach, painful arc on exam, normal radiographs." → Best next step: PT + NSAIDs for 6 weeks (not MRI, not surgery, not opioids)

Pattern 2 — Full-thickness cuff tear: "62-yo fell on outstretched arm, unable to actively abduct, drop arm positive, passive ROM preserved." → Best next step: MRI shoulder + orthopedic referral

Pattern 3 — Frozen shoulder: "55-yo diabetic woman, insidious shoulder pain and stiffness, cannot reach behind back, both active and passive external rotation severely limited, normal radiographs." → Diagnosis: adhesive capsulitis. Best initial step: intra-articular steroid injection + structured PT, optimize glycemic control

Pattern 4 — Calcific tendinitis: "Acute severe shoulder pain, calcium deposit on XR." → Treat with NSAIDs, ultrasound-guided barbotage, ± steroid injection

Pattern 5 — Cervical radiculopathy disguised as shoulder pain: "Shoulder pain radiating down arm, positive Spurling's, reduced biceps reflex." → MRI cervical spine, not shoulder

Pattern 6 — Polymyalgia rheumatica: "72-yo with bilateral shoulder and hip stiffness, morning stiffness >1 hour, ESR 65." → Low-dose prednisone (15 mg daily); screen for GCA

Pattern 7 — Pancoast tumor: "Smoker with shoulder pain, ptosis, miosis." → CXR / CT chest

Pattern 8 — Septic joint post-injection: "Day 5 post steroid injection, fever, worsening pain, effusion." → Aspirate, culture, IV antibiotics, ortho consult

Pattern 9 — Post-seizure posterior dislocation: "Patient after seizure, arm internally rotated, cannot externally rotate." → Posterior dislocation (often missed on AP view; axillary view confirms)

Pattern 10 — Cardiac mimic: "60-yo diabetic woman with left shoulder pain on exertion." → ECG and troponin first, not MSK workup

Pattern 11 — Conservative care first: Most stems testing whether you'll order PT before MRI in atraumatic shoulder pain

Pattern 12 — Elderly with NSAID contraindication: Switch to topical NSAID or acetaminophen + PT + consider injection

Pattern 13 — Workers' comp with chronic pain: Avoid opioids, emphasize active PT, set return-to-work goals

Board pearl: When the stem describes loss of both active AND passive ROM with normal radiographs in a 40–60 yo (often diabetic) woman, the answer is adhesive capsulitis — and the next step is intra-articular steroid injection + PT, not MRI.

One-Line Recap

Shoulder pain in primary care is dominated by rotator cuff tendinopathy/impingement, rotator cuff tears, and adhesive capsulitis — managed first with structured PT and NSAIDs, escalated to MRI and orthopedic referral only after failure of conservative therapy or in acute traumatic full-thickness tears, with intra-articular steroid injection as the procedural backbone for frozen shoulder.

High-yield recap bullets:

Diagnosis is clinical: ROM pattern (active vs passive), strength testing (drop arm, ER lag, belly-press), and provocative tests (Neer, Hawkins) distinguish the three core syndromes — imaging confirms, it does not diagnose.

Initial workup: plain radiographs (AP int/ext, scapular Y, axillary); MRI reserved for suspected full-thickness tear, failed conservative therapy, or pre-surgical planning; check HbA1c and TSH in frozen shoulder.

Conservative first: 6–12 weeks of structured PT + NSAIDs + activity modification for impingement, tendinopathy, partial tears, and frozen shoulder; intra-articular steroid injection is first-line procedural therapy for early frozen shoulder.

Escalate to orthopedics for acute traumatic full-thickness tears (within 3–6 weeks to optimize repair), failed conservative therapy at 3 months, refractory frozen shoulder >12 months, recurrent instability, or septic joint.

Never miss: ACS in left shoulder pain with risk factors, Pancoast tumor in smokers with shoulder pain + Horner, septic joint post-injection, cervical radiculopathy mimicking shoulder pain, and polymyalgia rheumatica in elderly with bilateral girdle stiffness.

Step 3 essence: The right answer is usually PT + time + targeted re-evaluation at 6 weeks, not reflex imaging or surgical referral — but recognize the acute traumatic tear and the septic joint, and act fast when they appear.