Shoulder pain is very common, it accounts for 1.2% of all general practitioner encounters in Australia. Shoulder pain could arise in or around the shoulder from its joints and surrounding soft tissues. Joints include the glenohumeral, acromioclavicular, and sternoclavicular joints. Bursae and motion planes include the subacromial bursa and scapulothoracic plane.
Because the shoulder pain is complex, it is important to figure out what are the underlying pathology that causing the lingering pain in the shoulder. The common shoulder pain disorders include frozen shoulder (adhesive capsulitis), rotator cuff disorders, subacromial/subdeltoid bursitis, referred pain (cervical spine, ischaemic heart disease), central sensitisation (polymyalgia rheumatica, fibromyalgia), myofascial pain. Hence, comprehensive biopsychosocial assessment is essential to provide a tailored targeted treatment.
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Prevalence of Shoulder Pain
The prevalence of shoulder disorders has been reported to range from 7% to 36% of the population, accounting for 1.2% of all General Practitioner encounters in Australia, being third only to back and neck complaints as musculoskeletal reasons for primary care consultation.
The shoulder is frequently injured, particularly in competitive sports. 8% to 13% of athletic injuries involve the shoulder.
Analysis from a community-based rheumatology clinic in the UK, 65% of cases were rotator cuff lesions, 11% were caused by localised tenderness in the pericapsular musculature, 10% involved acromioclavicular joint pain, 3% involved glenohumeral joint arthritis, and 5% were referred pain from the neck.
Rotator cuff tendinopathy is the most common cause of shoulder pain. An occupational history with repetitive movement or heavy lifting is normally related to this disease. A rotator cuff tear is usually strongly indicated by trauma in young people and atraumatic in elderly people, which is likely attributed from bone spurs or cuff degeneration.
Frozen shoulder (adhesive capsulitis) and true glenohumeral arthritis are often preceded by history of deep joint pain and restricted activities. Adhesive capsulitis is more common in people with diabetes and may also occur after prolonged immobilisation.
Acromioclavicular disease is usually secondary to trauma or osteoarthritis. Signs of inflammation, such as pain, tenderness, swelling are localised to the joint, with restriction in movement across another shoulder.
Often, shoulder pain could be referred from the cervical spine, especially when the lower cervical spinal segments developed arthritis and spread across upper back and shoulders. Other commonly seen conditions, include myofascial pain where the is associated with inflammation or irritation of muscle or of the fascia surrounding the muscle.
Hence, when we looking at the targeted pain mechanism to treat the shoulder pain, we should consider the following:
- Nociceptive: Tissue Injury e.g. rotator cuff injury, glenohumeral joint capsulitis/arthritis, bursitis, myofascial pain, osteoarthritis
- Neuropathic: Nerve Injury e.g. nerve impingement, referred pain from cervical spine
- Nociplastic: Sensitised Nervous System e.g. nonspecific shoulder pain, fibromyalgia