🔑 Key Learning

  • Common causes include rotator cuff disorders, adhesive capsulitis, osteoarthritis of the glenohumeral joint, and AC joint pathology.
  • RC tendinopathy causes subacromial pain and painful arc.
  • Adhesive capsulitis presents with progressive stiffness and loss of external rotation.
  • OA of the GH joint causes global stiffness and joint space narrowing on XR.
  • AC joint pain is worse on cross-body movements and localised to the ACJ.

🧬 Pathophysiology

Shoulder pain can arise from tendons, joints, bursa or referred pain. Common pathologies affect the rotator cuff (RC), glenohumeral joint (GHJ), or acromioclavicular joint (ACJ).

🦴 Rotator Cuff Disorders

Anatomy

SITS muscles:

  • Supraspinatus – ABduction (first 15°)
  • Infraspinatus – External rotation
  • Teres minor – ADduction and external rotation
  • Subscapularis – Internal rotation and ADduction
Figure 226: The Rotator Cuff Muscles. InjuryMap, CC BY-SA 4.0.

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🔥 Rotator Cuff Tendinopathy / Impingement

  • Inflammation/tendinopathy of the RC tendons beneath the acromion.
  • RFs: Age 35–80, repetitive overhead use, athletes.

👀 Clinical Features

  • Lateral shoulder pain (esp. subacromial)
  • Worse with overhead movement
  • Night pain common

🧪 Examination

  • Painful arc (70–120°)
  • Pain on resisted abduction
  • Painful active and passive ROM

💊 Management

  • Analgesia:
    • 1st line: Paracetamol
    • 2nd line: Oral NSAID or codeine
  • Physiotherapy
  • Subacromial corticosteroid injection if persistent

❌ Rotator Cuff Tear

  • Often post-traumatic (e.g. fall/dislocation)

👀 Features

  • Severe shoulder pain and marked weakness
  • Inability to abduct above 90°
  • Positive drop arm test

💊 Management

  • Urgent ortho referral

🧊 Adhesive Capsulitis (Frozen Shoulder)

  • Fibrosis of the GHJ capsule → pain + progressive stiffness
  • Strongly associated with diabetes and thyroid disease

👀 Clinical Features

  • Painful shoulder → becomes progressively stiff → limits daily activities
  • External rotation particularly limited

📈 Course

  1. Painful phase (3–9 months) - Progressive shoulder pain, especially on movement
  2. Stiff phase (6–12 months) - Progressive stiffness and deteriorating range of movement which limits function 
  3. Resolution phase (1–4 years) - Gradual improvement in stiffness and restoration of function 

💊 Management

  • Analgesia:
    • 1st line Paracetamol
    • 2nd line: oral NSAID/codeine
  • Early physiotherapy
  • Consider intra-articular corticosteroid

🦴 Glenohumeral Joint Osteoarthritis

  • Often secondary to trauma or RC tear
  • Primary GHJ OA is rare

👀 Features

  • Age > 60
  • Deep joint pain
  • Markedly reduced ROM, esp. external rotation
  • XR: LOSS (Loss of space, Osteophytes, Sclerosis, Subchondral cysts)

💊 Management

  • 1st line: Paracetamol
  • 2nd line: Topical NSAID
  • 3rd line: Oral NSAID/codeine
  • Intra-articular corticosteroid if inadequate relief
Figure 228: Shoulder x-ray demonstrating glenohumeral osteoarthritis in a 78 year old patient. Note the loss of joint space, osteophytic spurs and subchondral sclerosis. Jmarchn, CC BY-SA 3.0

   

🧱 Acromioclavicular Joint Disorders

💢 ACJ Osteoarthritis

  • RF: Age > 60, weightlifting
  • Pain over ACJ, worse with overhead movement or cross-body adduction

💥 ACJ Injury

  • Ligament/tendon injury after trauma or fall
  • Tender ACJ, painful elevation

📝 Exam Clues & Clinchers

  • Lateral deltoid pain + painful arc + night pain → Rotator cuff tendinopathy
  • Sudden shoulder pain following trauma + weakness/drop arm → Rotator cuff tear
  • Gradual stiff shoulder + limited external rotation + diabetes → Adhesive capsulitis
  • Deep joint pain + reduced global ROM + XR changes (LOSS) → Glenohumeral OA
  • Pain localised to AC joint + worse on cross-body movement → ACJ pathology