41-02: Musculoskeletal Injuries of the Shoulder

1. SUBACROMIAL IMPINGEMENT SYNDROME

General Considerations

The shoulder is a ball and socket joint. The socket is very shallow, however, which enables this joint to have the most motion of any joint. The shoulder, therefore, relies heavily on the surrounding muscles and ligaments to provide stability. The subacromial impingement syndrome describes a collection of diagnoses that cause mechanical inflammation in the subacromial space. Causes of impingement syndrome can be related to muscle strength imbalances, poor scapula control, rotator cuff tears, subacromial bursitis, and bone spurs.

With any shoulder problem, it is important to establish the patient’s hand dominance, occupation, and recreational activities because shoulder injuries may present differently depending on the demands placed on the shoulder joint. Baseball pitchers with impingement syndrome may report pain while throwing, while older adults with even full-thickness rotator cuff tears may not report any pain because the demands on the joint are lower.

Clinical Findings

A. Symptoms and Signs

Subacromial impingement syndrome classically presents with one or more of the following: pain with overhead activities, nocturnal pain with sleeping on the shoulder, or pain on internal rotation (eg, putting on a jacket or bra). On inspection, there may be appreciable atrophy in the supraspinatus or infraspinatus fossa. The patient with impingement syndrome can have mild scapula winging or “dyskinesis.” The patient often has a rolled-forward shoulder posture or head-forward posture. On palpation, the patient can have tenderness over the anterolateral shoulder at the edge of the greater tuberosity. The patient may lack full active range of motion but has preserved passive range of motion. Impingement symptoms can be elicited with the Neer and Hawkins impingement signs (Table 41–1).