The shoulder is a shallow joint with a large range of movement. The humeral head is held in place by the rotator cuff, which is part of the joint capsule. It comprises the tendons of infraspinatus and teres minor posteriorly, supraspinatus superiorly and teres major and subscapularis anteriorly.
The rotator cuff (particularly supraspinatus) prevents the humeral head blocking against the acromion during abduction; the deltoid pulls up and the supraspinatus pulls in to produce a turning movement and the greater tuberosity glides under the acromion without impingement. Shoulder pathology restricts or is made worse by shoulder movement. Specific diagnoses are difficult to make clinically but this may not matter for pain management.
Pain in the shoulder can sometimes be due to problems in the neck. Adhesive capsulitis (true frozen shoulder) is uncommon. Early inflammatory arthritis and polymyalgia rheumatica in the elderly may present with shoulder pain. Shoulder pain is more common in diabetic patients than in the general population.
A tendon is a cord that connects muscle to bone. Most tendinitis is a result of inflammation in the tendon.
Generally, tendinitis is one of two types:
• Acute. Excessive ball throwing or other overhead activities during work or sport can lead to acute tendinitis.
• Chronic. Degenerative diseases like arthritis or repetitive wear and tear due to age, can lead to chronic tendinitis.
This is a common cause of shoulder pain at all ages. It follows trauma in 30% of cases and is bilateral in under 5%. The pain radiates to the upper arm and is made worse by arm abduction and elevation, which are often limited. The pain is often worse during the middle of the range of abduction, reducing as the arm is raised fully; a so-called ‘painful arc syndrome’.
Torn rotator cuff
This is caused by trauma but also occurs spontaneously in the elderly and in rheumatoid arthritis (RA).
Shoulder pain causes include:
• Avascular necrosis (death of bone tissue due to limited blood flow)
• Brachial plexus injury
• Broken arm
• Broken collarbone
• Bursitis (joint inflammation)
• Cervical radiculopathy
• Dislocated shoulder
• Frozen shoulder
• Heart attack
• Osteoarthritis (disease causing the breakdown of joints)
• Polymyalgia rheumatica
• Rheumatoid arthritis (inflammatory joint disease)
• Rotator cuff injury
• Separated shoulder
• Septic arthritis
• Sprains and strains
• Tendon rupture
• Thoracic outlet syndrome
• Torn cartilage