Description

Shoulder pain is a common condition affecting patients of all ages:

• Causes include acute trauma or overuse during sports and activities of every day living.
• Age plays an important role in determining the etiology of shoulder pain.
• Onset and characteristics of pain, weakness, mechanism of injury, and functional limitation also help in diagnosing and treating shoulder pain.

Epidemiology

• Shoulder pain accounts for 16% of all musculoskeletal complaints.
• The lifetime prevalence of shoulder pain is as high as 70% (1).
• Predominant age:
  • <30 years: Shoulder instability
  • >30 years: Rotator cuff (RTC) disorder:
    • 30–50 years: Tendinopathy
    • 40–60 years: Partial tear
    • >60 years: Full-thickness tear
  • >60 years: Osteoarthritis (OA) of the glenohumeral joint

Incidence
The incidence of shoulder pain is 6.6–25 cases/1,000 patients, with a peak incidence in the 4th–6th decades.

Risk Factors

• Repetitive overhead activities
• Overhead and upper extremity weight-bearing sports (baseball, softball, swimming)
• Weight lifting: Acromioclavicular (AC) disorders
• Rapid increases in training frequency, improper technique
• Muscle weakness or imbalance
• Trauma or fall onto the shoulder
• Diabetes, thyroid disorders, female gender, age 40–60 years are risk factors for adhesive capsulitis.

General Prevention

• Maintenance of good shoulder strength and range of motion (ROM)
• Avoidance of repetitive overhead activities
• Proper technique (pitching, weight-lifting)

Pathophysiology

Depends on underlying etiology

Etiology

• Trauma (fracture, dislocation, ligament/tendon tear)
• Overuse (RTC pathology, biceps tenosynovitis, bursitis, muscle strain):
  • RTC disorders most commonly occur from repetitive overhead activity. This leads to impingement of the RTC that can progress through 3 stages:
    • Stage I: Tendinopathy
    • Stage II: Partial RTC tear
    • Stage III: Full-thickness RTC tear
  • Subacromial bursitis can occur with RTC disorders, but is rarely an isolated diagnosis.
• Age-related (AC and glenohumeral joint OA, adhesive capsulitis, RTC tear; pediatric athletes instability and physeal injuries)
• Rheumatologic (rheumatoid arthritis, polymyalgia rheumatica, fibromyalgia)
• Referred pain (neck, gallbladder)