The shoulder complex is built for mobility, however, this ability to move comes with the designation of being the most unstable joint in the body. The shoulder is composed of three osseous joints and one articulation, with stability provided by muscles, ligaments, the glenoid labrum and joint capsule.
There are different degrees of instability including instability and laxity in one direction, multidirectional instability, shoulder subluxation and shoulder dislocation. When referring to shoulder instability, we are referring primarily to the glenohumeral joint.
The glenohumeral joint is a ball and socket joint between the head of the humerus bone (ball) and the glenoid fossa of the scapula (socket) or shoulder blade. The head of the humerus is large and the glenoid fossa is small, resulting in an unstable but mobile joint.
The shoulder depends on ligaments, muscles and the labrum for stability. Therefore, if a person has loose ligaments or weak muscles the shoulder can become unstable. The shoulder does not actually dislocate, but can slide around in the glenoid fossa. Repetitive overhead activities can also produce instability. Anterior instability is the most common.
- Weakness of the rotator cuff and laxity of the glenohumeral ligaments are the most common cause of shoulder instability.
- General ligamentous laxity may predispose an individual to instability or dislocation.
- Repetitive strain injuries (RSI) at work, or overuse activities are common in people who participate in sport activities and individuals who have jobs that require performing activities of a repetitive nature, like working on an assembly line.
- Those participating in activities like swimming or activities characterized by overhead motion like tennis, softball, baseball, volleyball, overhead throwing and other repetitive sport activities may aggravate the shoulder, resulting in shoulder instability.
- Sudden trauma or accident like a fall on the shoulder or a fall when the arm is placed in an abducted externally rotated position (hand behind head) can also cause a shoulder dislocation.
- General tenderness of the shoulder area
- Discomfort with movement, especially with overhead activities
- Pain with overhead activities or sleeping on the affected side
- Feeling that the arm is “dead” after repeated activity
- A feeling that the shoulder will “go out” when reaching up and behind the head. This is called the Apprehension Sign.
Treatment of Shoulder Instability (Unidirectional Instability)
Conservative treatment of shoulder instability is the first line of action. This includes physical therapy to reduce inflammation and associated pain. In addition, a regiment of exercises to improve rotator cuff strength and shoulder stability should be initiated. In more severe cases of instability involving the glenoid labrum, surgical intervention may be necessary.
Physical Therapy Interventions
Physical Therapists are professionals, educated and trained to administer interventions. As stated in The Guide to Physical Therapist Practice interventions are the skilled and purposeful use of physical therapy methods and techniques to produce changes consistent with the diagnosis, prognosis, and the goals of the patient or client. Common interventions in the treatment of Shoulder Instability include:
- Manual Therapeutic Technique (MTT): hands-on care, including soft tissue massage, and joint mobilization by a physical therapist to modulate pain and reduce any soft tissue or tendon irritation.
- Therapeutic Exercises (TE) including strengthening exercises to improve strength of the rotator cuff muscles in the shoulder and increase stability.
- Neuromuscular Re-education (NMR) to restore stability, begin retraining the upper extremity, improve proximal joint stability and improve movement technique and mechanics (for example, throwing or reaching overhead) in daily use of the involved upper extremity.
- Modalities that can include the use of ultrasound, electrical stimulation, ice, cold laser, and others to decrease pain and inflammation at the shoulder and tendons.
- Home program that includes strengthening, stretching and stabilization exercises as well as instructions to help the person perform daily tasks and advance to the next functional level.
Procedures that your physician may recommend and perform in addition to physical therapy.
- Relocation and initial immobilization of the dislocated shoulder
- REST and ICE
- The use of NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)
- Steroidal Injections to reduce inflammation
- Pain medication to reduce the discomfort and allow the patient to perform the recommended exercises
- Surgery to correct underlying pathology and avoid instability and repeated dislocations. This may include labral repairs or procedures to tighten the shoulder capsule or ligaments.
Most people recover full function following a course of conservative care of physical therapy to strengthen and stabilize the shoulder. Those with more involved situations such as labral tears, chronic dislocations and/or rotator cuff tears will require surgery and intensive physical therapy afterward to restore full function.