Shoulder instability

Overview

The shoulder is a “ball and socket” joint that is comprised of the humeral head (the “ball”) and the glenoid (“socket”). The humeral head is the top part of the upper arm bone (humerus) while the glenoid is a very shallow socket located on the shoulder blade (scapula). The term “shoulder instability” is used to describe what happens when the humeral head separates from the glenoid. This can be a very quick partial separation that lasts only a few seconds (subluxation), or it can be a more significant condition where the ball and socket get stuck in the dislocated position.

When a shoulder instability event occurs, it can also cause other damage to the shoulder such as tears of the labrum (rim of soft cartilage tissue around the glenoid), cartilage injuries, rotator cuff tears, or even fractures. Shoulder instability can occur following a traumatic accident such as a fall or collision with another athlete or object. It can also occur without significant trauma or injury, and this type of shoulder instability is more common in people who are exceptionally flexible with “loose” joints or connective tissue problems such as Ehlers Danlos.

  • Feeling or hearing a “pop” in the shoulder
  • Significant pain and an inability to move the shoulder
  • Feeling that the shoulder is stuck in a certain position
  • Sensation of increased movement in the ball and socket joint of the shoulder
  • Weakness or difficulty lifting the arm overhead

Seek immediate care if any injury to your shoulder causes signs or symptoms of a shoulder dislocation. While many dislocations quickly come back into place on their own, others require the attention of a medical professional to relocate the joint. Because it is well known that multiple shoulder instability events can increase the risk of injury to surrounding structures in the shoulder (cartilage, labrum, rotator cuff, etc.), it is important to get a prompt and accurate diagnosis to determine the severity of the injury and determine an appropriate plan for treatment. This is particularly true for younger patients (under age 30) as they are at the highest risk for repeat dislocations.

Shoulder instability can occur by a number of different mechanisms:

  • Falling onto the arm
  • Sliding or diving headfirst
  • Collision with another person or object
  • Overuse of the shoulder leading to muscle fatigue/weakness
  • Seizure disorders

There are a number of factors that increase your risk of shoulder instability:

  • Being young and participating in contact sports such as football, basketball, hockey, and wrestling
  • Having a history of previous injury to the shoulder
  • Having generalized ligamentous laxity (loose ligaments) that is commonly seen in swimmers, volleyball players, dancers, and patients with connective tissue problems
  • Seizure disorders

Nonoperative management with focused physical therapy, activity modification, and possibly bracing is considered as the first line of treatment for patients with shoulder instability. This treatment is successful in the majority of patients and they are able to get back to their regular activities in a matter of weeks to months. For those who are high risk for recurrence (young, contact athlete, etc.), those who experience multiple instability events, and those who have other damage to the shoulder (cartilage tears, fractures, etc.), surgery may be considered. While there are a number of different surgical treatment options, all are aimed at improving the stability of the shoulder and allowing patients to get back to the activities they desire as soon as is safely possible.

People who experience a shoulder dislocation are at higher risk of developing arthritis in the shoulder. This is particularly true for those who experience multiple dislocations or instability events. The more instability a patient has, the higher the risk that they cause damage to other structures in the shoulder such as the cartilage, bone, and/or rotator cuff. Accordingly, treatment is focused on reducing the risk for repeat instability events and reducing the risk of developing these other injuries.

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