What is Shoulder Instability?
The shoulder is comprised of three bones; the humerus (upper arm bone), scapula (shoulder blade), and the clavicle (collarbone). The top of the humerus bone (humeral head) joins the shoulder socket (the glenoid, which is part of the scapula) to form the shoulder joint (glenohumeral joint). The glenoid is a very shallow socket. Attached circumferentially to the edge of the socket is the labrum, which is a bumper of tissue somewhat like the orange rubber gasket on a mason jar. The ligaments that hold the ball in the socket attach to the labrum, and both the labrum and the ligaments provide stability to the shoulder. Because the glenoid is almost flat and not a deep bony socket like the hip socket, the glenohumeral joint allows for more range of motion than any other joint in the body. However, this freedom of motion also makes the shoulder joint the most susceptible to dislocations and instability.
Shoulder instability is a condition in which the humeral head gets pushed out of the glenoid. The humeral head usually gets pushed completely off the edge of the glenoid (a glenohumeral joint dislocation). However, the humeral head can get pushed only partially out of the glenoid (a glenohumeral joint subluxation).
Dr. Cunningham is a shoulder specialist at Vail Summit Orthopaedics and Neurosurgery. He is an expert at diagnosing and treating shoulder instability for patients in Vail, Summit County, Aspen, and Denver, CO.
What Causes Shoulder Instability?
- Trauma resulting in a shoulder dislocation: With a hard fall, we typically reach out with our hand to brace our fall. As our hand impacts the ground, the arm is pulled out away from our body. When this happens, the humeral head can be levered completely out of the glenoid and dislocate. If this occurs, the labrum and the ligaments attached to the labrum are usually torn away from the front edge of the glenoid, as the humeral head typically goes out the front. If the labrum and ligaments tear with a dislocation, they usually do not heal back to their correct position. This can then lead to recurrent
- Multidirectional Instability: Some patients, particularly young women and girls, have generalized looseness of all their ligaments. These patients are often known to be “double jointed,” such that they can move joints beyond the normal range of motion. In their shoulder, they may feel the shoulder slide out of place during fairly simple actions, such as reaching behind for something. Certain overhead sports such as swimming and volleyball may slowly stretch ligaments out further, increasing one’s feelings of instability in the shoulder. These patients can have shoulder subluxations or complete dislocations. With glenohumeral joint subluxations, the labrum is not typically torn off the edge of the socket, but the ligaments are partially torn and stretched as the humeral head repeatedly slides part way out of the socket.
How is Shoulder Instability Diagnosed?
Orthopedic attention is recommended for patients with symptoms of shoulder instability in order to get an accurate diagnosis. A history is taken from the patient and a physical examination performed. It is important to understand whether these instability episodes occurred as a result of trauma or not. As part of an exam, shoulder range of motion is checked. The arm is brought into certain positions to check if the patient becomes apprehensive. The ball is gently translated within the socket in multiple directions to see which ligaments have been stretched out and what is the main direction of instability.
Diagnostic imaging is performed. An X-ray will indicate any injury to the bones of the shoulder complex. An MRI provides detailed imaging of the labrum, ligaments, tendons, and the surrounding soft tissues of the shoulder joint.
Does Shoulder Instability Resolve?
Depending on one’s age and activity level, many patients can recover from a shoulder dislocation or subluxation and not have further problems. Initially, rest the shoulder to allow injured structures to heal. Apply ice to decrease pain and inflammation. Take NSAID’s or Tylenol if needed for pain. Physical therapy is helpful to slowly regain full range of motion and to work on strength. Strengthening the rotator cuff and other supporting muscles is critical. A full return to sports may take 3-4 months. Once cleared for sports, it may be recommended to use protective gear (ie. a Sully brace) if you are participating in any high risk activities like football.
How To Treat Recurrent Shoulder Instability?
If one continues to experience repeated dislocation or subluxation events, it is important to seek treatment so that the condition does not worsen. Young patients, particularly males who engage in contact sports like football, are at particularly high risk of having further dislocations after sustaining a first time dislocation. The more instability episodes that occur, the more complexly torn the labrum and ligaments become. There can also be cartilage damage that occurs due to the shear forces of the humeral head forcefully sliding out of the shoulder socket.
Surgical options include:
- Arthroscopic labral repair in which the torn labrum is sewn back up on the edge of the glenoid where it was attached prior to the dislocation. At the same time, any stretched shoulder ligaments are tightened by cinching them together with strong suture. This procedure has a high success rate for eliminating further dislocations. Arthroscopic procedures to the shoulder have the overriding benefit of being minimally invasive, thus allowing for a quicker recovery. This is an outpatient procedure.
- Latarjet procedure: In cases where the bone of the shoulder socket has been worn away by recurrent instability episodes, it is important to restore the normal shape and size to the socket. In a Latarjet procedure, a bone with its attached tendons that is located right next to the front of the socket is transferred over to the front edge of the socket, thus restoring the normal shape and size to the socket. This surgery is done on an outpatient basis.
Dr. Cunningham is a shoulder specialist at Vail Summit Orthopaedics. He is an expert at diagnosing and treating shoulder instability for patients in Vail, Summit County, Aspen, and Denver, CO. Contact Dr. Cunningham today.