Recurrent shoulder dislocation

In terms of proportions, the shoulder can be likened to a golf ball sitting on a “tee”, the “tee” being part of the scapula (glenoid). The capsule and ligament envelope, along with the rotator cuff, prevent the humeral head from slipping forward or backward. At the humerus, this “envelope” inserts directly into the bone, while at the glenoid, it attaches to a ring of cartilage called the labrum that resembles the meniscus in the knee. Following a trauma, the capsule, ligaments or labrum can tear or separate from the bone of the glenoid, leading to instability. Other episodes of shoulder dislocation can then occur and this is called recurrent dislocation. If the injury that causes the initial dislocation occurs at a young age (e.g., under 20 years of age), the risk of the shoulder remaining unstable and requiring surgical repair is higher. However, when the injury occurs at a more advanced age (e.g., over 50 years of age), it is more likely to be associated with a rotator cuff tear. The residual problem will be weakness and pain rather than instability. Magnetic resonance imaging (MRI) or a CT scan and arthrography are performed to identify large lesions of the ligaments or labrum. Repeated episodes of dislocation may lead to a defect in the humeral head (Hill-Sachs lesion) and osteoarthritis may develop. Glenohumeral dislocation is not always a result of trauma, especially in subjects with ligament hyperlaxity (abnormally high flexibility).

Nonsurgical treatment for recurrent shoulder dislocation

In general, after an initial dislocation in a young subject, conservative treatment (immobilization for a few weeks followed by physiotherapy) is usually sufficient. In people over 25 to 30 years of age, short-term immobilization and physiotherapy can be initiated rapidly. In subjects over 50 years of age, especially if there is weakness once the shoulder is repositioned, urgent investigation by MRI or ultrasound is important to ensure that the rotator cuff has not been torn. With or without damage to the cuff, early mobilization is essential to prevent ankylosis. If there is a large rotator cuff tear, surgery will be necessary. If a glenohumeral dislocation is not traumatic and the patient has abnormally loose ligaments (structural), the usual treatment is intensive physiotherapy (which can sometimes take several months); the goal is to substitute muscle stability for a capsule-ligament deficiency. When dislocation occurs, the nerve that supplies the deltoid muscle (axillary or circumflex nerve) may be stretched, causing paralysis of this muscle. Healing, which takes a few weeks to a few months, usually occurs on its own. If there is no sign of healing after a few months, a referral to neurology (EMG) is indicated.

Surgical treatment of recurrent glenohumeral dislocation

The goal is to reconstruct the anatomy as it was before the initial dislocation. CT arthrography, MRI or, better still, MR arthrography is done first to determine the nature of the lesion.

If a large bone fragment has separated from the glenoid, fixation of the fragment or a bone graft will be necessary (open surgery).

For a first-time surgery, except when there is extensive bone damage, I prefer the arthroscopic approach. The procedure involves the repair or reinsertion of the capsulolabral complex and, in some cases, capsular plicature also.

Small bioabsorbable or metal implants are inserted in the glenoid (scapula) to anchor the labrum or capsule in the bone structure.

The intervention, which is a reconstruction of the anatomy as it was before the initial dislocation, may be performed under locoregional (my preference) or general anesthesia. The procedure takes 30 to 90 minutes. The patient is allowed to leave the clinic a few hours after his surgery and the surgeon determines the length of immobilization (usually two to four weeks) as well as the physiotherapy program. Complete healing usually take four to six months. The long-term success rate is 85% to 90% and range of motion is gradually restored until it returns to normal.

I use the open approach for bone repair or bone grafts and for recurrences after a first arthroscopic repair. The latter type of repair has a higher rate of complications (mainly neurological) than the open approach. Since it causes more scarring, it further solidifies the “anterior wall” of the shoulder, often resulting in loss of movement and an increased risk of developing osteoarthritis. The success rate of the open approach is nearly 95%.

In cases of ligament hyperlaxity without tissue damage, surgery may be open or arthroscopic. However, surgery is rarely necessary, since nonsurgical treatment is effective in almost 90% of patients if followed for six consecutive months. The success rate of open and arthroscopic surgery is lower, since the capsule and ligaments tend to stretch again over time.

Posterior dislocations are much rarer and their treatment is a posterior version of the treatment for an anterior dislocation. It should be noted that when posterior dislocation occurs as a result of a seizure, electric shock or acute state of inebriation, there is often destruction of the humeral head as well, which could require prosthetic replacement. A CT scan is always recommended in these situations.

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