UW Health's Sports Medicine doctors treat a wide range of common athletic injuries.
Shoulder instability refers to a variety of disorders that result in dislocation, subluxation (partial dislocation) or a general lack of stability of the glenohumeral (ball and socket) joint. Individuals may experience shoulder instability because of trauma or congenital laxity (extra movement you inherit) of shoulder structures, or because of weakness and improper biomechanics (poor movement patterns). Medical professionals classify shoulder instability according to the degree of extra movement, how often instability occurs, the tissues affected and the direction in which the shoulder becomes unstable.
Signs and Symptoms
Anterior Instability is the most common type of shoulder instability. Approximately 90% of all shoulder dislocations occur in this direction. Active populations that find themselves in an externally rotated (hand away from the body) and abducted (arm away from body) position are the most vulnerable (Figure 1).
Posterior Instability is much less common than anterior instability. Athletes or patients sustaining traumatic forces may sustain posterior instability. However, the most common mechanism for posterior instability is dramatic involuntary muscle contraction by the shoulder. Examples of this include seizure or electric shock.
Multi-directional Instability is most commonly associated with congenital shoulder laxity or the development of laxity because specific shoulder muscles (rotator cuff) are weak or not functioning appropriately. Athletes and patients who have multidirectional instability are often involved in, and have the most symptoms with, repetitive, overhead activities.
Management and Treatment
Immediate Treatment of Acute Dislocation
Immediate treatment involves “reducing” or putting the shoulder back in place as soon as possible. The longer your shoulder is out of place the more difficult it may be to reduce it. This is because of muscle spasm and pain. It is often necessary to administer sedation (relaxation) medication to allow for an appropriate reduction. X-rays will usually be performed before and after reduction to confirm that there are no accompanying fractures and to document an appropriate reduction.
Your shoulder will be placed in a sling for a period of time to allow for healing and comfort. Researchers are currently looking into the optimal position of immobilization to assist healing tissues. More physicians are beginning to use slings that keep your shoulder in a neutral or subtly externally rotated position.
Long Term Treatment Options
Treatment for shoulder instability involves identifying how and when your shoulder becomes unstable. Your age and activity level will often play a large role in determining whether your physician will recommend conservative management (therapy) vs. a surgical intervention. The extent of the tissues injured will also be crucial in determining a direction for care. You will need to identify whether your shoulder is unstable during high demand activities or whether simple activities of daily living contribute to your condition. You will also need to identify whether modifications in activities are reasonable/acceptable to your quality of life. Factoring in this information, your physician will be able to more accurately estimate what probability exists for continued episodes of instability.
Recurrent episodes of instability have been extensively documented. Active individuals less than twenty years of age have on average, a 90% chance of recurrent instability. These percentages drop as we age mainly because we are not as active or provocative on our shoulders.
Conservative Management Strategies
Non-surgical interventions will emphasize recovering range of motion (ROM), strength and normal mechanics to your shoulder. Below is a common progression used in the rehabilitation of shoulder instability (Table 1).
If conservative management has failed or you have been identified as a high risk to have further instability, your physician may recommend a surgical intervention. Surgical procedures will address injured or loose tissues in an attempt to give the shoulder anatomical stability. Procedures include arthroscopy, open surgery and radiofrequency capsular tightening. All of these procedures will be considered based on your specific situation. This will enable your physician to choose the most effective procedure possible.
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Conservative Management Strategies
- Phase 1: Rest and immobilization, pain control, reduce secondary injury (relative rest)
- Phase 2: ROM-adduction and flexion emphasis, early isometric srengthening, early isotonic strengthening
- Phase 3: Strength evolution, goal of reaching 90% strength in the injured shoulder when compared to the uninjured, endurance emphasis
- Phase 4: Pain-free provocative position rehabilitation, increase and emulate sport or job specific demand, return to sport or job activities