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Adhesive Capsulitis (Frozen Shoulder)

Description:
Progressive, painful restriction of range of motion (ROM) in the glenohumeral (GH) joint.
Course: pain diminishes over time but residual pain and limited active/passive ROM may persist.

Subtypes:
- Primary AC:
- Idiopathic, usually associated with diabetes mellitus (DM)
- Typically resolves in 9 to 24 months
- Secondary AC:
- Due to prolonged immobilization
- Commonly complication of rotator cuff impingement syndrome (tendonitis)
- Sometimes called "shoulder-hand syndrome" (a form of complex regional pain syndrome [CRPS] or reflex sympathetic dystrophy [RDS]) characterized by shoulder pain, swelling, decreased ROM

Clinical Course:
| Phase | Duration | Characteristics | |-------------|----------------|----------------------------------------------------------| | Phase 1 | 2 to 9 months | Painful phase; constant pain; diagnosis difficult early | | Phase 2 | 4 to 12 months | Stiffening/freezing; external rotation especially limited| | Phase 3 | 12 to 42 months| Resolution/thawing; gradual return to normal mobility |

Epidemiology

  • Incidence: 2.4 per 1,000 people/year
  • Female:Male ratio: 1.4:1
  • Prevalence: 2-5% general population, 10-20% in diabetes (1)

Etiology and Pathophysiology

  • Idiopathic with inflammation and scarring
  • Histology: mast cells, T & B cells, macrophages β†’ elevated inflammatory cytokines (IL-1, IL-6, TNF-Ξ±, COX-1/2) (1)
  • Elevated markers for neoangiogenesis (CD34) and neoinnervation (GAP43, PGP9.5, NGFRp75) β†’ explains acute pain phase
  • Overexpression of TGF-Ξ² linked to AC in animal models (1)
  • Capsular contracture: joint volume reduced to 3-4 mL (normal 10-15 mL)
  • Fibroblasts and myofibroblasts cause scarring, especially in rotator interval (coracohumeral ligament [CHL], biceps tendon, GH capsule)
  • Contracture of GH capsule with loss of synovial layer and adhesions
  • Elevated ICAM-1 facilitates leukocyte migration; increased in AC and DM

Risk Factors

  • Shoulder immobilization (most significant)
  • Increasing age
  • Female gender
  • Diabetes mellitus
  • Thyroid disease
  • Atherosclerotic cardiovascular disease (ASCVD) – CVA, MI, hyperlipidemia
  • Antiretroviral medication use
  • Parkinson disease
  • Trauma or surgery
  • Prior AC in contralateral shoulder

General Prevention

  • Maintain active lifestyle avoiding shoulder injury
  • Control diabetes, ASCVD, thyroid, autoimmune diseases

Commonly Associated Conditions

  • Diabetes mellitus
  • Autoimmune disorders
  • Parkinson disease
  • Highly active antiretroviral therapy (HAART) use
  • Cerebrovascular accident (CVA)/myocardial infarction (MI)
  • Cervical disc disease
  • Thyroid disorders

Diagnosis

History

  • Identify risk factors
  • Progressive worsening stiffness of GH joint
  • Early disease: diffuse shoulder pain predominates
  • Late disease: stiffness predominates
  • Rule out: fractures, osteoarthritis (OA), subacromial pathologies (bursitis, rotator cuff tendinopathy), cervical radiculopathy, GH arthrosis (1)

Physical Exam

  • Limitation of both active and passive ROM due to mechanical restriction
  • Capsular pattern: external rotation most limited, then abduction, then flexion
  • Pain on rotator cuff impingement tests
  • Inability to reach overhead or back pocket
  • Scapular substitution during active movement
  • Loss of arm swing during gait

Differential Diagnosis

  • Rotator cuff strain/tear/impingement syndrome
  • GH or acromioclavicular joint OA
  • Cervical strain/radiculopathy/OA
  • Subacromial bursitis
  • Parsonage-Turner syndrome (brachial plexus inflammation)
  • Myofascial pain syndrome
  • Calcific tendonitis
  • Fracture
  • Shoulder subluxation/dislocation
  • Bony neoplasm/metastasis

Diagnostic Tests & Interpretation

  • Clinical diagnosis; labs/imaging as needed for associated conditions
  • Labs: check diabetes, thyroid disease, autoimmune diseases, Parkinson disease if risk factors present (e.g., TSH, HbA1c, ESR, CRP)
  • Imaging:
  • Plain radiographs: posteroanterior, external rotation, axillary, supraspinatus outlet views; primarily to exclude other pathologies
  • MRI: only if concomitant shoulder pathology or neuro deficit suspected
    • Findings: thickening of joint capsule and CHL, edema, increased joint fluid
    • Rotator interval/axillary capsule enhancement and inferior GH/CHL hyperintensity have >80% sensitivity/specificity (2)
  • Ultrasound: similar indications to MRI; reveals CHL thickening, joint capsule changes, increased fluid
    • Doppler US may show increased vascularity near biceps tendon and CHL

Follow-Up Tests & Special Considerations

  • Shared decision-making on treatment
  • Referral pain for CRPS evaluation

Diagnostic Procedures

  • Injection test may differentiate AC from rotator cuff tendinopathy (improves with local anesthetic injection unlike AC)
  • Reserved for uncertain diagnosis after thorough history and exam

Treatment

  • Mostly self-limited
  • Physical therapy with exercises limited by pain
  • Manage expectations: resolution can take up to 18 months
  • Treat underlying conditions (DM, thyroid)

Medication

  • Symptomatic relief: acetaminophen, NSAIDs first-line
  • Glucocorticoid injections:
  • Single or multisite IA corticosteroid injections provide significant pain relief early in disease (<1 year duration) lasting up to 6 months
  • Physical therapy after injection (4-6 weeks) improves pain and ROM
  • Injection often diluted with lidocaine
  • Common corticosteroids: Triamcinolone or Methylprednisolone 20-40 mg
  • Hydrodilation: saline + corticosteroid injection may speed ROM recovery (1)
  • Oral steroids provide short-term relief but less effective than IA injections

First Line

  • Conservative: home exercises like "climbing the wall"
  • Face wall, place hand flat, "climb" wall with fingers, pause 30 sec every few inches
  • Repeat turning torso 90Β° to wall (abduction)
  • Can combine with NSAIDs or corticosteroid injections
  • Oral steroids generally not recommended

Second Line

  • No improvement after 6-8 weeks: consider more invasive treatment
  • Hydrodilatation with saline/lidocaine + glucocorticoid
  • Continue physical therapy

Issues for Referral

  • Surgical referral if symptoms >1 year and no progress after 3 months management

Additional Therapies

  • Daily gentle ROM exercises; structured plan recommended
  • Physical therapy beneficial especially in phases 2 and 3, ideally combined with corticosteroids
  • Laser therapy: suggested for pain relief; insufficient evidence
  • Suprascapular nerve block: temporary pain relief, option if refractory to IA steroids; evidence limited (1)
  • Other studied therapies: whole-body cryotherapy, IA botulinum toxin A injection (limited evidence)

Surgery / Other Procedures

  • Reserved for refractory patients after 1 year conservative treatment
  • Procedures:
  • Manipulation under anesthesia (MUA)
  • Arthroscopic capsular release (ARC)
  • Distension arthrogram
  • No clear superiority between ARC, MUA, and physiotherapy in pain/function improvement

Ongoing Care

  • Follow-up in 3-4 weeks after diagnosis for pain control and start NSAIDs + gentle exercise with PT guidance
  • Consider IA corticosteroid injections if no significant improvement
  • Physical therapy should continue concurrently to hasten recovery and increase ROM
  • For secondary AC, manage underlying condition
  • Consider surgery if no improvement

Patient Education

  • Explain prognosis and importance of compliance
  • Teach "climbing the wall" exercise as above
  • Emphasize treating underlying causes in secondary AC

Prognosis

  • Recovery depends on treatment timing, symptoms, and comorbidities
  • Duration variable: 1 to 3 years without intervention
  • Idiopathic frozen shoulder has good recovery rate

References

  1. Le HV, Lee SJ, Nazarian A, et al. Adhesive capsulitis of the shoulder: review of pathophysiology and current clinical treatments. Shoulder Elbow. 2017;9(2):75-84.
  2. Suh CH, Yun SJ, Jin W, et al. Systematic review and meta-analysis of MRI features for diagnosis of adhesive capsulitis of the shoulder. Eur Radiol. 2019;29(2):566-577.

ICD10 Codes

  • M75.00 Adhesive capsulitis of unspecified shoulder
  • M75.01 Adhesive capsulitis of right shoulder
  • M75.02 Adhesive capsulitis of left shoulder

Clinical Pearls

  • AC (frozen shoulder) is a self-limiting global restriction of shoulder ROM; ~15% have long-term disability
  • Natural course: painful, freezing, thawing phases
  • Mostly affects older women; prevalence 3-5% general population, 10-20% diabetic population
  • Active and passive ROM restriction present; external rotation most limited
  • Pain on subacromial provocation; inability to reach overhead/back pocket common
  • Plain x-rays preferred initial imaging; MRI/US only if concomitant pathology or neurologic deficit
  • Treatment: pain control, PT, corticosteroids; surgery if refractory
  • Symptom resolution can take up to 24 months
  • Also called the "50-year-old shoulder" due to prevalence in middle-aged patients