Shoulder Pain: Causes, Symptoms and Treatment

The shoulder is the most mobile joint in the human body – capable of movement in multiple planes. This extraordinary range of motion comes at a price: the shoulder is also one of the most commonly injured and painful joints. Shoulder pain can come from many different structures and often the cause is not immediately obvious.

In this guide, I'll walk through the most common causes of shoulder pain, how they are diagnosed, and what treatments are available – including when surgery is needed.

Anatomy of the Shoulder: Why It's Complex

The shoulder joint involves three bones (humerus, scapula, clavicle) and four separate joints. The rotator cuff – a group of four muscles and their tendons – provides dynamic stability. Any of these structures can be a source of pain.

Common Causes of Shoulder Pain

1. Rotator Cuff Tears

The rotator cuff consists of four muscles (supraspinatus, infraspinatus, teres minor, subscapularis). Tears can be partial or complete, and occur due to injury or degeneration. Symptoms: Weakness in raising the arm, pain at night, difficulty reaching overhead or behind the back. Treatment: Physiotherapy for partial tears; arthroscopic rotator cuff repair for complete or large tears.

2. Shoulder Impingement Syndrome

The rotator cuff tendons become compressed (impinged) under the acromion bone with overhead movements. Symptoms: Pain with overhead activity, reaching across the body, combing hair. Often worse at night. Treatment: Rest, anti-inflammatories, physiotherapy, steroid injections. Surgery (subacromial decompression) if conservative treatment fails.

3. Frozen Shoulder (Adhesive Capsulitis)

The shoulder capsule becomes inflamed and thickened, leading to severe stiffness. Three phases: Freezing (pain dominates), Frozen (stiffness dominates), Thawing (gradual recovery). Duration: 1–3 years typically. Treatment: Physiotherapy, steroid injections, hydrodilation (distension arthrogram), and in refractory cases, arthroscopic capsular release.

4. Shoulder Dislocation and Instability

The ball (humeral head) slips out of the socket (glenoid). Common in young athletes and following trauma. Recurrent dislocation leads to instability. Treatment: First dislocation: reduction (putting it back), immobilisation, physiotherapy. Recurrent dislocation in young patients: Arthroscopic Bankart repair to restore labral attachment.

5. SLAP Lesion (Labrum Tear)

The labrum (cartilage rim of the shoulder socket) tears, often at the superior aspect (top). Common in throwing athletes and people who fall on an outstretched hand. Symptoms: Deep ache, clicking, weakness; pain with throwing or overhead activities. Treatment: Physiotherapy first; arthroscopic repair for persistent cases in active patients.

6. Acromioclavicular (AC) Joint Injury

The joint between the clavicle and shoulder blade. AC joint injuries are common in rugby, cycling and wrestling. Symptoms: Pain and swelling at the top of the shoulder; step deformity in severe cases. Treatment: Minor injuries: physiotherapy. Severe injuries: surgical stabilisation.

7. Shoulder Arthritis

Less common than hip and knee arthritis, but can cause severe pain and stiffness in the shoulder. Treatment ranges from physiotherapy and injections to total shoulder replacement in end-stage cases.

Diagnosis of Shoulder Pain

• Clinical examination: Specific tests identify which structure is affected
• X-ray: Shows bone abnormalities, calcification, arthritis, AC joint injury
• MRI scan: Gold standard for soft tissue – shows rotator cuff tears, labrum, bursitis
• Ultrasound: Useful for dynamic assessment of tendons; can guide injections

Treatment Options for Shoulder Pain

• Conservative: Rest, ice/heat, anti-inflammatory medications, physiotherapy
• Injections: Subacromial steroid injection, AC joint injection, hydrodilation for frozen shoulder
• Arthroscopic Surgery: For rotator cuff tears, Bankart repair, SLAP repair, subacromial decompression, frozen shoulder release
• Open Surgery: For complex reconstructions and shoulder replacement

When to See an Orthopaedic Surgeon

• Shoulder pain lasting more than 4–6 weeks
• Pain that wakes you from sleep
• Significant weakness in the arm
• After a shoulder dislocation (especially the first time, in young patients)
• Inability to lift the arm above shoulder height
• Following a trauma with possible fracture

Early and accurate diagnosis leads to the best outcomes. Many shoulder conditions respond excellently to non-surgical treatment when caught early.