Description

• Compression of rotator cuff tendons and subacromial bursa between the humeral head and the structures comprising the coracoacromial arch and proximal humerus
• Most common cause of atraumatic shoulder pain in patients >25 years of age
• Primary symptom is pain that is most severe when the arm is abducted between 60 and 120 degrees (the “painful arc”).
• Classically divided into three stages:
  • Stage I: acute inflammation, edema, or hemorrhage of the underlying tendons due to overuse (typically in those aged <25 years)
  • Stage II: progressive tendinosis that leads to partial rotator cuff tear along with underlying thickening or fibrosis of surrounding structures (commonly, ages 25 to 40 years)
  • Stage III: full-thickness tear (typically in patients aged >40 years)

Epidemiology

Incidence

• Shoulder pain accounts for 1% of all primary care visits.
• Peak incidence of 25/1,000 patients per year occurs in patients aged 42 to 46 years.
• Impingement responsible for 18–74% of shoulder pain diagnoses

Prevalence
Prevalence of shoulder pain in general population ranges from ~7% to 30%.

Risk Factors

• Repetitive overhead motions (throwing, swimming)
• Glenohumeral joint instability or muscle imbalance
• Acromioclavicular arthritis or osteophytes
• Thickened coracoacromial ligament
• Shoulder trauma
• Increasing age
• Smoking

General Prevention

• Proper throwing and lifting techniques
• Proper strengthening to balance rotator cuff and scapula stabilizer muscles