Frozen Shoulder

Aetiology

  • Primary idiopathic – best prognosis
  • Diabetic frozen shoulder – worse prognosis, protracted course
  • Secondary – worse prognosis
  • Neuromuscular – secondary to CVA, poor prognosis
  • Diabetes
    • 75% with FS have diabetes or undiagnosed insulin resistance
    • Diabetics have 10% lifetime risk of FS
  • Genetic
    • Increased risk in twins, some genetic link

Epidemiology

  • Women > men
  • Unusual <40 years and >70 years
  • Secondary FS can occur at any age
  • Unusual in manual workers
  • 85% unilateral
  • 20% develop subsequent contralateral FS
  • Recurrence in same shoulder uncommon
  • 15% bilateral simultaneous
    • Of these, 80% have recurrence within 5 years

Pathoanatomy

  1. First, the anterior superior capsule is affected
    • Corresponds to rotator interval
    • Capsule, CHL & SGHL involved
    • Restricted ER in adduction
  2. Anterior inferior capsular contracture follows
    • Capsule & IGHL involved
    • Restricted ER in abduction
  3. Posterior capsule contracture in severe cases
    • Restricted internal rotation
  4. Secondary FS
    • Extra-articular structures may also be contracted
    • Rotator cuff, especially subscapularis
    • More global stiffness

Histology

  • Inflammatory and fibrous tissue
  • Akin to Dupuytren’s when fibrotic
  • Type 3 collagen, fibroblasts, myofibroblasts & angiogenesis predominate
  • Type 3 collagen deposition causes stiffness

Natural History

  • Resolution occurs over 18-24 months
  • Three stages
    1. Freezing – very painful
    2. Frozen – pain subsides, stiffness predominates
    3. Thawing – stiffness improves
      (Significant overlap between stages)
  • 40% have persistent symptoms or signs at 5 years
  • Around 20% will have some functional deficit at 5 years

Clinical Features

History

  • Insidious onset or secondary to other pathology
  • Severe pain
  • Night pain
  • Burning
  • Diffuse in nature
  • CRPS-type character

Examination

  • ROM assessment
    • ER in adduction = rotator interval mainly
    • ER in abduction = anterior-inferior capsule
    • IR = posterior capsule
    • Global restriction = severe primary FS or secondary FS
  • Cuff power usually intact

Imaging

Plain X-ray

  • Exclude causes of secondary FS (e.g., calcific tendonitis)
  • Identify other causes of stiffness (e.g., dislocation, GHJ arthritis)

Other

  • MRI – if suspect cuff pathology
  • Blood glucose levels – screen for diabetes

Management

Goals

  • Relieve pain
  • Restore ROM
  • Restore function

Analgesia & Activity Modification

  • Useful in the acute painful period
  • Physiotherapy painful initially

Physiotherapy

  • Cochrane review – no significant benefit over doing nothing
  • Likely beneficial in
    • Limiting progression
    • Aiding recovery once it starts
    • Motivational & supervisory support

Steroids – Oral or Intra-Articular

  • Cochrane review – no long-term difference
  • Helpful for short-term pain & ROM but effects not sustained
  • Can cause rebound stiffness
  • Side effects limit use

Distension Arthrography

  • Reasonable evidence for medium-term benefit in primary FS
  • Less effective in secondary FS due to extra-articular contractures
  • Technique
    1. Arthrogram to confirm no cuff tear
    2. Insufflate joint until pressure decreases (capsular rupture)
    3. Steroid injection
    4. Aggressive physiotherapy

Manipulation Under Anaesthetic (MUA)

  • Good relief & ROM improvement
  • Limited high-level studies
  • More useful for anterior & anterior-inferior capsule tightness
  • Technique
    1. Interscalene block
    2. Short lever arm
    3. Order of Manipulation – FF, ER in ADD, ER in ABD, IR
    4. Steroid injection
    5. Physiotherapy

Arthroscopic Release

  • Better pain relief & functional improvement than MUA alone
  • Combine with MUA
    • Perform MUA first – increases space for arthroscopy
  • Treats anterior capsular contracture
  • Release technique
    • Interscalene block for post-op pain relief
    • Focus on releasing rotator interval structures
      • CHL, SGHL, MGHL, capsule
    • 360-degree release if persistent stiffness
    • More release = higher nerve injury risk
  • Combine with ASAD if extra-articular contracture present

Open Release

  • Rarely done
  • For failed arthroscopic release
  • If metalware needs removal or bony lesions need excision
  • More painful

Treatment Algorithm

  1. Try physio, analgesia & activity modification first
  2. If no improvement & patient wants treatment → proceed to MUA
  3. Treat concurrent pathology if secondary FS
  4. If MUA unsatisfactory → proceed to arthroscopic release
  5. Use a steroid injection after any procedure & liberal use of IS blocks
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