Frozen shoulder

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"frozen shoulder" OR "adhesive capsulitis"

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Frozen Shoulder (Adhesive Capsulitis)

Definition

Frozen shoulder syndrome (FSS), or adhesive capsulitis, is a condition characterized by limited range of motion of the glenohumeral joint (GHJ) with pain at the extremes of movement. It was first described by Putman in 1882 and later by Codman. The term "adhesive capsulitis" was coined by Neviaser to describe a contracted, thickened joint capsule drawn tightly around the humeral head with relative absence of synovial fluid and chronic inflammatory changes in the subsynovial layer.

Firestein & Kelley's Textbook of Rheumatology, p. 899
Campbell's Operative Orthopaedics 15th Ed (2026), p. 2839

Epidemiology

Incidence approximately 2% in the general population
Age range 40-70 years; peaks in women in their 40s and 50s
~70% of patients are women
20-30% develop adhesive capsulitis in the contralateral shoulder
In diabetics, bilateral disease occurs in 50% of cases
Rarely recurs in the same shoulder
Campbell's Operative Orthopaedics, p. 2839

Etiology and Risk Factors

The exact cause is unknown. It is frequently associated with:

Risk Factor	Notes
Diabetes mellitus	Insulin-dependent patients ~5x more likely; no association with HbA1c level
Female sex	Accounts for ~70% of cases
Age > 49 years
Prolonged immobilization	Most significant precipitating factor
Thyroid disorders	Hypo- and hyperthyroidism
Cardiovascular disease / MI	Can occur after myocardial infarction
Stroke
Cervical disc disease
Trauma / surgery	Even minor surgery at a remote site (e.g., hand) can precipitate FSS
Autoimmune diseases
Hyperlipidemia	Proposed risk factor - evidence still evolving
Apical lung tumor, TB	Rarer associations

Classification (Lundberg): "Primary" (no identifiable inciting event) vs. "Secondary" (after precipitant trauma or surgery). Surgical post-op shoulder stiffness is a form of secondary FSS but behaves more like an arthrofibrosis.

Campbell's Operative Orthopaedics, p. 2839-2840
Firestein & Kelley's, p. 899

Pathophysiology

The underlying process involves:

Diffuse inflammatory synovitis of the shoulder capsule and synovium
Reactive capsular fibrosis - fibroblastic proliferation driven by cytokines (TGF-beta1, metalloproteinases 2 and 9)
Adherence and contraction of the capsular surfaces - loss of the axillary pouch and reduced joint volume
Neoangiogenesis and neo-innervation - increased nerve growth factor receptor expression may explain the severe pain
Alarmin molecules (e.g., HMGB1) are elevated in frozen shoulder capsules and correlate with pain severity

The CB1 (cannabinoid receptor 1) pathway has also been implicated in the pathogenesis.

Campbell's Operative Orthopaedics, p. 2839-2840

Clinical Stages

Three-Phase Model (Clinical)

Phase	Name	Duration	Features
1	Painful / Freezing	Weeks to months	Severe pain, exacerbated by movement; arm held adducted and internally rotated; night pain
2	Adhesive / Stiffening (Frozen)	4-12 months	Minimal pain; progressive stiffness; periscapular compensatory symptoms; loss of ADLs
3	Resolution / Thawing	5-26 months	Pain eases; motion slowly returns; some patients improve dramatically

Four-Stage Arthroscopic Staging (Neviaser/Campbell)

Stage	Arthroscopic Appearance
1	Pre-adhesive: fibrinous inflammatory synovitis with early adhesion formation
2	Acute adhesive synovitis with synovial proliferation; early adhesions in inferior capsular fold
3	Maturation: less synovitis, more fibrosis; axillary fold obliterated
4	Chronic: fully mature adhesions
5	Thawing phase

Campbell's Operative Orthopaedics, p. 2840
Firestein & Kelley's, p. 899

Clinical Features

Pain: diffuse, dull ache around the shoulder, referred to upper arm, back, and neck; worst at night; inability to sleep on the affected side
Stiffness: global limitation - internal and external rotation lost first, then flexion; typically can only internally rotate to sacrum, 50% loss of ER, and <90° abduction
Nondominant arm usually affected
Pathognomonic sign: loss of active external rotation (Bailey & Love)
Both active AND passive movement restricted (distinguishes from rotator cuff pathology where passive ROM is preserved)
On passive ER testing: a sense of mechanical restriction is appreciated

Diagnosis

Diagnosis is clinical - based on history and physical examination showing restricted active and passive range of motion not due to other causes. There are no universally accepted formal criteria.

Investigations:

X-ray: usually normal; excludes osteoarthritis, fracture, calcific tendinitis, missed dislocation
Ultrasound/MRI: not routinely needed; characteristic MRI findings exist but rarely change management - useful to rule out other conditions
Blood tests: CBC, ESR, serum chemistry, TFTs to screen for an underlying metabolic cause
Tc-99m bone scan: may show increased uptake; more useful to exclude occult lesions or metastasis in uncertain cases
Rosen's Emergency Medicine, p. 662
Harrison's Principles of Internal Medicine 22E, p. 3018

Differential Diagnosis

Calcific tendinitis
Rotator cuff tear / tendinosis
Subacromial bursitis
GH joint osteoarthritis
Chronic posterior GHJ dislocation (similar ER limitation)
Polymyalgia rheumatica (when both shoulders affected)
Infection, fracture
Cervical radiculopathy

Management

Conservative (First-Line)

Treatment	Notes
NSAIDs	Symptom relief; first-line in ED
Intra-articular / subacromial corticosteroid injection	Most benefit in painful (freezing) phase; transient pain relief in ~2/3 patients
Physiotherapy / exercise	Gentle stretching and assisted range-of-motion exercises; passive and active movement encouraged throughout
Heat application	Adjunct modality
TENS	Adjunct modality
Patient education	Reassurance about self-limiting nature; essential given the slow resolution

Hydrodilatation (distension injection): Slow forceful injection of contrast material (or 20-30 mL local anaesthetic ± steroid) into the joint lyses adhesions and stretches the capsule - improves shoulder motion and facilitates physiotherapy.

Surgical / Interventional (for refractory cases)

Manipulation under anaesthesia (MUA): accelerates return to normal function; one study showed 78% return to work within 2.6 months post-MUA
Arthroscopic capsular release: releases the tight capsule; produces good pain relief and motion improvement
Reserved for patients who fail conservative treatment over a prolonged period

Prevention

Avoid prolonged immobilization after minor shoulder injury
Early mobilization after shoulder injuries, surgery, or MI
Identify at-risk patients (diabetics, post-cardiac surgery patients) proactively
Bailey and Love's Surgery, p. 552
Rosen's Emergency Medicine, p. 662
Firestein & Kelley's, p. 899

Prognosis

Generally self-limiting - resolves spontaneously in most cases within 1-3 years
Diabetic patients tend to have a prolonged course (often considerably longer than 2 years)
Many patients are left with some residual limitation of shoulder motion even after resolution
Rarely recurs in the same shoulder
Harrison's, p. 3018; Bailey and Love's, p. 552

Recent Evidence (2024-2026)

Three relevant systematic reviews published recently:

Pharmacological interventions (2024) - A network meta-analysis (PMID: 38538951) in Rheumatology (Oxford) evaluated pharmacological options for early-stage frozen shoulder.
End-range physiotherapy interventions (2024) - A systematic review and meta-analysis (PMID: 37559358) in Disability & Rehabilitation examined end-range mobilization approaches for primary adhesive capsulitis.
Radiofrequency ablation (2024) - A systematic review (PMID: 38988077) assessed radiofrequency ablation as a pain management option for shoulder pain including frozen shoulder.

These do not fundamentally change the management approach described above, but the pharmacological network meta-analysis may refine the relative positioning of intra-articular steroid vs. other agents in the freezing phase.

Sources: Firestein & Kelley's Textbook of Rheumatology | Campbell's Operative Orthopaedics 15th Ed (2026) | Harrison's Principles of Internal Medicine 22E | Rosen's Emergency Medicine | Bailey and Love's Short Practice of Surgery 28th Ed

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