Rotator cuff disorders:

• Usually affect people 35 years of age or older.
• If the person is younger than 50 years of age, consider a tendonitis of the cuff, or possible partial thickness tear. If the person is 50 years of age or older, consider a rotator cuff tear.
• Most pain occurs when performing overhead activities.
• On examination, a painful arc of movement between 60–120 degrees of abduction is found. Pain can also occur on the front and side of the shoulder, and at night.
• Active range of movement is limited, but there is a full passive range of movement.
• Massive rotator cuff tear is suggested if there is a history of trauma or dislocation, severe pain, profound weakness of abduction, or an inability to maintain the arm in 90 degrees of abduction then lower it to the side slowly (positive drop arm test).

Frozen shoulder:

• Common in people older than 40 years of age (if older than 60 years, also consider arthritis). More common in women and people with diabetes.
• May occur secondary to trauma, but the cause is often unknown.
• Frozen shoulder progresses through several stages:
• Pain:
• Gradual onset of aching upper arm pain which can become severe, can radiate down the arm (not below the elbow), and disturbs sleep at night because of the person's inability to lie on the affected side. Diagnosis can be difficult at this stage before stiffness becomes evident.
• Stiffness:
• There is global (in all directions) limitation of both active and passive range of movement, including restriction of external rotation with elbows held at 90 degrees and upper arms held at the sides, and limitation of abduction. Function is substantially limited. Pain is less severe (rest pain and night pain have usually subsided) but is still present at the end of the range of movement.
• Resolving phase:
• Gradual improvement in range of movement with less discomfort. There may be residual mild restriction of range of movement.
• Additional features:
• Can affect one, or both shoulders (but rarely together).
• The affected arm may be held in adduction and internal rotation.
• Tenderness over anterior capsule.
• No weakness.

Anterior dislocation:

• History of trauma. Typically involves a fall with the arm externally rotated and abducted.
• Pain and muscle spasm.
• Empty space below the acromion (empty socket) with the humeral head anterior.
• Limited movement.

Instability disorders:

• Usually occurs in people younger than 35 years of age.
• History of dislocation/subluxation.
• Common with overhead work or sports.
• Symptoms may be vague (e.g. athletic young males with activity-related pains in their shoulder, or an inability to perform an overhead throw due to pain). Affected people often describe 'dead arm' symptoms — tingling, weakness, numbness, shoulder fatigue, clicking, locking, or a 'popping' sensation.
• Increased laxity and pain on testing.

Acromioclavicular joint disorders:

• Injuries usually occur in people 20–50 years of age, more commonly in men, mostly in people involved in contact sports, or following a fall on to the shoulder (e.g. rugby, skiing, cycling).
• Localized joint tenderness and limitation of movement due to pain. Pain can also occur on top of the shoulder, especially when the arm is brought across the body, or during weightlifting activities.
• Deformity of the acromioclavicular joint suggests dislocation.
• Osteoarthritis of the acromioclavicular joint tends to occur in older people.

Glenohumeral joint osteoarthritis:

• Typically occurs in older people, or following traumatic injury in younger people.
• Chronic pain that is worse on movement.
• Less specific distribution of pain than other shoulder disorders.
• Decreased range of motion, both actively and passively.

[Tallia and Cardone, 2003; NZGG, 2004; Dias et al, 2005; Hazleman, 2005; Codsi, 2007; NHS Lothian, 2007a; NHS Lothian, 2007b; Burbank et al, 2008; Mitchell, 2008]