Anterior Shoulder Instability
What is Anterior Shoulder Instability?
The primary bones that make up the shoulder are the humerus, scapula, and clavicle. The glenohumeral joint is the “ball-and-socket” joint of the shoulder formed by the head or “ball” of the humerus and the cup or “socket” of the glenoid (which is the lateral part of the scapula)—as shown in Figure 1. The shoulder is the most moveable joint in your body. It helps you lift your arm, rotate it, and reach up over your head. It is able to turn in many directions. This greater range of motion, however, results in less inherent stability. Some people are born with very lax ligaments with remarkably increased motion and instability. This is called multidirectional instability, but is not addressed here.
Traumatic shoulder instability occurs when the head of the humerus is forced out of the shoulder socket anteriorly during dislocation. This may occur from a sudden injury or from overuse of the shoulder joint. Once a shoulder has dislocated once, it is more vulnerable to dislocation again. Recurrent shoulder dislocations at the glenohumeral joint make the ligaments that hold the shoulder in place become lax, causing the shoulder to become loose and slip out of place repeatedly, causing chronic shoulder instability. Associated labral tears contribute to the instability. The typical tear is anterior interior called a “Bankart” or “Perthes” lesion (as shown in Figure 2 below).
Signs and Symptoms:
The most common symptom of anterior shoulder instability is pain in the shoulder after dislocation, and continued pain when shoulder is externally rotated. Patients may also notice a loss of shoulder function, tenderness, inflammatory swelling, and catching, popping, or sense of apprehension or instability when rotating the shoulder out away from the body. As symptoms intensify, patients may notice a loss of strength, deformity at the shoulder joint, crepitation (crackling feeling) with shoulder motion, and numbness in the upper arm from pinching, stretching or pressure on the blood vessels or nerves. The pain may worsen with heavy lifting and may wake the patient up at night.
Conservative options (following acute shoulder reduction for dislocation) include immobilization, ice, anti-inflammatory medications or a steroid injection to temporarily reduce pain and swelling. Conservative treatment may be a good option for children and for patients who do not require an extreme range of motion on a consistent basis in their jobs or hobbies (such as baseball pitchers or gymnasts). Avoidance of activities that promote subluxation or dislocation is encouraged. A sling or shoulder immobilizer may be recommended for 3 – 8 weeks to protect the joint while the ligaments heal after dislocation. (There is currently some debate on which rest position is best–whether an internal rotation position or an external rotation “gunsling” position should be maintained.) Following immobilization, stretching and strengthening of the joint and surrounding muscles will be necessary under the direction of a therapist.
If conservative treatment is not effective in minimizing shoulder pain, instability, and recurrent dislocation, a stabilizing procedure such as a Capsular Shift and Bankart Repair of the shoulder may be recommended. The goals of surgical repair are to improve shoulder comfort and function and to stabilize the shoulder to prevent further sublaxations or dislocations. Either an Open technique or Arthroscopic technique may be used.
1. Arthroscopic repair is the most common repair used in anterior shoulder instability. The advantages of an arthroscopic repair include smaller incisions, less postoperative pain, and an easier, if not shorter, rehabilitation period. Younger patients and even contact athletes are suitable candidates for arthroscopic stabilization procedures. The surgeon will make several very small incisions and use an arthroscope to see inside the shoulder joint. After the torn labrum is identified, suture anchors are used to repair the torn tissue back to its anatomic location—this is called a Bankart Repair. The anterior inferior capsule is shifted anterior superiorly. This results in a double layer of tissue reinforcing the Bankart repair. The small incisions are then sutured or taped closed. The patient is placed in a shoulder immobilizer with the shoulder at the side and internally rotated to the chest.
2. Open repair – The surgeon will make a shirt-crease like incision and incise both the subscapularis and the anterior glenohumeral ligaments and capsule to expose the glenoid rim. Surgical anchors or suture will be used to reattach the labrum and glenohumeral ligament to the glenoid (called a Bankart Repair as shown in Figure 3). To help prevent recurrence the sheet of tough fibers that surrounds the glenoid and humerus, called the capsule, will be tightened and reinforced using a portion of the inferior capsule. The inferior capsule is split and shifted anterior, superior, and then sutured back to the humerus overlapping the anterior capsule (called a Capsular Shift as shown in Figure 4). This results in a double layer of tissue reinforcing the Bankart repair. The subscapularis is then repaired and the skin is sutured closed. The patient is placed in a shoulder immobilizer with the shoulder at the side and internally rotated to the chest.
Post Operative Rehabilitation:
Note: These instructions are to serve as guidelines and are subject to Physician discretion. Actual progress may be faster or slower depending on the individual.