Subacromial impingement syndrome

• Subacromial impingement syndrome (SAIS):

  • inflammation and irritation of the rotator cuff tendons as they pass through the subacromial space resulting in pain, weakness and reduced range of motion within the shoulder
  • Most common cause of shoulder pain
  • Caused by conditions that result in the reduction of the subacromial space resulting in the humeral head compressing/impinging tendons or bursa, or both
  • Supraspinatus tendon is the most commonly affected tendon
• Causes - inflammation within subacromial space:

  • Rotator cuff tendinosis
  • Subacromial bursitis (more common in younger patients)
  • Calcific tendinitis - calcium deposits in rotator cuff tendons - exact cause unknown, more common in people aged 30-60
• Causes - issues with bone causing narrowing of subacromial space:

  • Anatomic variation of the acromion e.g. curved rather than flat
  • Development of bony spurs on the acromion
• Risk factors:

  • Commonly seen in people who participate in activities requiring repetitive overhead activities
  • Age - peak incidence in 60s
• Symptoms:

  • Pain when lifting the arm or when lying on the affected side
  • Onset usually gradual - over weeks to months
  • Often pain is felt over lateral acromion with radiation to the lateral mid-humerus
  • Weakness and stiffness can occur secondary to the pain
• Examination:

  • May have weak abduction and tenderness on palpation over coracoid process
  • Painful arc - pain between 60-120 degrees implies SAIS
  • Jobe's/empty can test - pain indicated tendon impingement (weakness indicates tear)
• Diagnosis:

  • Clinical diagnosis but sometimes imaging can help support diagnosis:
  • X-ray shoulder: assess for issues with bone causing narrowed subacromial space e.g. osteophytes, shape of acromion, can see calcium deposit (calcific tendonitis)
  • USS: assess tendons and bursa
  • MRI allows detailed look at bone and soft tissue structures
• Management:

  • Physiotherapy and exercise programmes
  • Analgesia - regular paracetamol, if ineffective consider oral NSAID or codeine
  • Steroid injection
  • If not responding to conservative management or diagnosis is uncertain refer to secondary care
  • Surgical management - tendon repair, remove bursae, remove section of acromion
• Prognosis:

  • Majority will respond to conservative management