Shoulder Instability Causes, Symptoms & Treatment Options

The shoulder is formed at the junction of three bones: the head of the humerus (the long bone of the upper arm), the scapula (shoulder blade), and the clavicle (collarbone). The head of the humerus fits into a cavity of the scapula, called the glenoid fossa, to form the glenohumeral joint.

The shoulder is a very flexible joint with a great range of motion. These characteristics allow us to perform actions like throwing a ball. However, they also make the shoulder unstable and more susceptible to injuries like dislocation. The shoulder is the most unstable joint in the body.

Shoulder instability is the inability of the shoulder’s ligaments and muscles to keep the humeral head in the glenoid fossa. Instability can cause the humerus to slip out of the socket and dislodge or dislocate. Instability can be partial, called a shoulder subluxation, or complete, called a dislocation.

• Subluxation: A partial shoulder dislocation that occurs when the head of the humerus slightly leaves the glenoid fossa.
• Dislocation: A dislocation occurs when the head of the humerus completely leaves the glenoid fossa. Dislocations can be traumatic (due to an injury, such as an impact) or atraumatic (the shoulder becomes loose due to stretching of the capsule). When the shoulder is dislocated due to a traumatic event, it often tears the labrum (a ring of cartilage inside the glenoid cavity that serves as the attachment site of the shoulder ligaments).

Shoulder instability can occur in three different ways:

• Anterior instability: The humerus is forced out of the joint through the front of the shoulder.
• Posterior instability: The humerus is forced out of the joint through the back of the shoulder.
• Multidirectional instability: The humerus leaves the joint in multiple directions.

Shoulder instability is classified into either

• Traumatic instability
• Atraumatic instability

Joint looseness and instability are common in these sports:

• Football
• Rugby
• Swimming
• Volleyball
• Basketball

Shoulder instability may be painful or your shoulder may just feel loose. You may have shoulder instability is you notice

• Your shoulder feels loose or out of place (joint looseness)

If you have shoulder instability you may want to see your doctor

During your appointment your doctor may

• Examine your shoulder for signs of instability
• Look for signs of laxity or looseness in other joints
• Obtain X-Rays
• Obtain an MRI or CT scan to further evaluate the joint

If it is your first time that your shoulder has popped out or feels loose but has not completely popped out, your doctor may recommend conservative or non-operative treatment. This may consist of a home exercise program or a supervised program with a licensed physical therapist to strengthen the muscles around the unstable shoulder joint.

Try these exercises to help address your condition:

Below is a PDF of the Exercise Program

Shoulder Instability

• If you have injured the muscles or ligaments of the shoulder, you may need surgery to repair damaged tissue and/or to tighten any ligaments that are stretched out. If you have more than one dislocation, oftentimes, surgery is suggested to stabilize the shoulder.
• The type of procedure performed will depend on many factors, including:
• Whether the shoulder is dislocating out of the back or the front of the joint
  If there is any damage to the bone
  The number of times the shoulder has been dislocated
• Generally, in simple cases, surgery can be done arthroscopically. Arthroscopic surgery is a minimally invasive surgical technique which uses several tiny incisions (roughly one centimeter long) through which special instruments and a camera, attached to a thin, flexible tube, are inserted. During arthroscopic surgery, the physician repairs the torn labrum by putting stitches in the torn tissue. In complicated cases, a more classic open procedure is needed to restore the stability of the shoulder joint.

• Your recovery time will vary depending on the extent of your injuries and whether you need surgery. In situations where surgery is not needed, your shoulder may be immobilized for 10 days to up to three weeks, followed by a course of physical therapy. Depending on the sport, you may be able to return to play in six weeks. However, in some higher demand sports, oftentimes play is restricted for three months. Your doctor may recommend that you wear a brace when you return to play for added protection.
• If you need surgery, you will be required to keep your arm in a sling for two to three weeks to allow the shoulder to heal. Full recovery can take up to six months. You can return to play when you have recovered full range of motion and strength and do not have pain.