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