Shoulder

The shoulder is a functional unit which is composed of two joints, the glenohumeral joint between the scapula (shoulder blade) and the humerus (upper arm bone) and the acromioclavicular joint between the acromion (part of the scapula) and the clavicle or collar bone.

The rotator cuff is a group of muscles which attach to the humerus and provide shoulder movement.

The muscles are attached to the bone by tendons which are prone to damage where they pass beneath the acromioclavicular joint. Arthritis and overgrowth of the acromioclavicular joint predisposes to such damage.

Normal Shoulder

The MRI scan taken coronally through the shoulder shows the tendon of supraspinatus, one of the muscles in the rotator cuff, passing beneath the acromioclavicular joint.

Supraspinatus Tear

The integrity of the rotator cuff is required for normal movement of the shoulder. A tear in one of the tendons of the rotator cuff can result in a painful, weak shoulder.

Symptoms
Painful, weak shoulder; in particular, difficulty raising the arm above the head.

MRI
The MRI shows a complete tear of the supraspinatus tendon.

Degenerative Acromio-clavicular Joint

Degenerative changes or osteoarthritis can be a feature of most joints in the body particularly in middle and later life and especially in patients who have pursued a physically demanding lifestyle.

Symptoms Pain and limitation of movement in the shoulder.

MRI
The MRI shows osteoarthritis of the acromio-clavicular joint (ACJ) with tendinopathy.

Shoulder Instability

Instability of the shoulder refers to either complete dislocation or partial dislocation of the glenohumeral joint. This may or may not be a direct consequence of an injury or trauma. Stability of the shoulder is dependant upon a combination of anatomical structures including the soft tissues, muscles, tendons, the joint capsule and ligaments.

Symptoms
Symptoms which can arise from instability include pain, intermittent locking and the sensation of an unstable joint. Particular athletic activities such as baseball pitching, throwing, athletic events and swimming can predispose to shoulder instability.

MRI
The MRI shows an indentation in the outline of the humeral head related to impaction during anterior dislocation, the so called Hill Sachs fracture.

Abnormalities of the Shoulder Labrum

Symptoms
Pain, instability, intermittent locking.

MRI
The MRI shows a tear of the glenoid labrum, the cartilage which lines the margin of the joint.

Shoulder Trauma

Injuries of the shoulder may be due to either direct trauma or dislocation. Often these will show up on normal X-rays, but MRI is an excellent way of demonstrating either bone bruising or fractures which have not shown up on X-Ray.

Symptoms
Pain and instability.

MRI
The MRI shows fracture of the humeral head.