Anatomy & Background
Shoulder subluxation is a partial and temporary dislocation of the shoulder joint that results when the head of the humerus partially slips out of the glenoid fossa – the socket of the shoulder blade (scapula). The condition can result from the underlying looseness of the shoulder ligaments, repetitive overuse activities, or it may be initiated by a sudden trauma to the shoulder.
The shoulder is built for mobility, with three osseous joints and one articulation. One of the joints, the glenohumeral joint, is a ball-and-socket joint that allows for mobility of the arm within the shoulder joint complex. Within this joint, the head of the humerus (upper arm bone), which is the “ball”, sits in the socket of the shoulder blade, known as the glenoid fossa. Although this joint is mobile, the fact that the humerus is large and the glenoid fossa is small results in an unstable joint.
Shoulder subluxation most commonly occurs following a fall (usually on an out stretched arm) or a direct trauma to the shoulder. Individuals with loose ligaments are more susceptible to this type of instability. Causes of shoulder subluxation include:
- Looseness or laxness of the glenohumeral ligaments are the most common cause of instability. This can result from a prior injury to the shoulder, such as a dislocation.
- General looseness of ligaments in the body can also predispose an individual to subluxation.
- Rotator cuff weakness makes individuals more prone to subluxation of the shoulder.
- Some connective tissue disorders can make individuals more prone to shoulder subluxation due to ligamentous laxity. Those who are double jointed are more prone as well.
- Repetitive strain injuries that result from overuse of the shoulder joint due to recreational or work-related activities may make shoulder subluxation more likely. Sports involving overhead motions, such as baseball, softball, tennis, volleyball or swimming can aggravate the shoulder, resulting in instability and looseness of the joint. Other sports that put people at increased risk include football, basketball and wrestling.
Signs and Symptoms of Shoulder Subluxation
Symptoms of shoulder subluxation generally include:
- Pain and discomfort with movement, especially overhead activities, or when sleeping on the affected side.
- Tenderness in the area of the shoulder joint.
- A feeling that the shoulder is loose or that it is “going in and out of joint” when reaching up or behind the head. This is referred to as the “apprehension sign”.
- Weakness of the shoulder joint.
- A feeling that the arm is “dead” or numb after repeated activity.
Treating Shoulder Subluxation
Treatment of shoulder subluxation is focused primarily on reducing your pain and any inflammation at the outset of the instability, as well as providing the patient with a course of physical therapy in order to strengthen the rotator cuff and stabilize the shoulder. Patients with an underlying pathology that causes prolonged or repeated subluxations may require surgical treatment to tighten the ligaments in the shoulder capsule or to make repairs to the glenoid labrum. If surgery is necessary, intensive physical therapy is required following surgery to restore full functionality of the shoulder joint.
Managing Your Pain
Initial treatment of shoulder subluxation typically focuses on temporarily resting the joint, as well as reducing pain and inflammation. This allows the patient to proceed through a course of physical therapy to strengthen and stabilize the shoulder. Pain management is achieved through:
- Sling – The shoulder may be initially immobilized in order to rest the joint during healing and to reduce pain.
- Rest – Use of the shoulder may be temporarily limited and movements that exacerbate pain and aggravate subluxation. Overhead activities should be avoided.
- Ice – Reduces inflammation and diminishes pain.
- NSAIDs and pain medication – Non-steroidal anti-inflammatory drugs reduce pain and inflammation. Additional pain medication may be required while therapeutic and strengthening exercises are performed.
- Steroid injections – Low doses of steroids injected into the glenohumeral joint can reduce inflammation.
- Physical therapy – Therapy is usually recommended to strengthen and stabilize the shoulder. Therapeutic exercises, neuro-muscular reeducation, manual therapy, electrical stimulation, ultrasound, cold laser therapy and ice can be utilized to decrease pain, reduce inflammation, improve mobility and strengthen the shoulder.
Shoulder subluxation is temporary and most patients fully recover following a conservative course of treatment that includes rest, medication to reduce pain and inflammation, and physical therapy to improve strength and stability. However, some patients with conditions that predispose them to ligamentous laxity, such as connective tissue disorders, as well as those with rotator cuff or labral tears, or loose ligaments from a prior shoulder injury, may require surgical treatment followed by an intensive course of physical therapy in order to return to full functionality.