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Shoulder Instability: Management, Reduction & Care
The shoulder joint is the least stable in the body. It features a shallow glenoid that interacts with a small part of the humeral head. Stability is provided by the shoulder capsule and ligaments, which can become torn when the shoulder dislocates. The typical mechanism of injury involves a force applied to an abducted, externally rotated, and forward-flexed extremity. After a traumatic shoulder dislocation, there is often an avulsion of the anterior labrum. A SLAP lesion (Superior Labrum from Anterior to Posterior tear) can result from excessive load through the long head of the biceps, such as falling while holding onto scaffolding. A Hill-Sachs lesion is a chondral impaction injury in the posterosuperior humeral head that occurs during the dislocation. The axillary nerve is commonly stretched following an anterior dislocation; hence, it is important to test sensation over the deltoid and assess deltoid contraction.
It is also necessary to evaluate patients for rotator cuff tears, as these are a relatively common complication of a dislocated shoulder, especially in elderly individuals.
Clinical Tests
There are several clinical tests that are helpful in the diagnosis of anterior shoulder instability. The most useful are the apprehension test and its variants (augmentation and relocation tests) 1. In the apprehension test, place the patient supine. The arm is then gently moved to 900 of abduction and 900 of external rotation. The test is positive when patients experience apprehension.
In the relocation test the patient experiences a decrease in apprehension when the humerus is pushed down (relocated) during apprehension testing. An augmentation test is positive when the patient experiences additional apprehension with an anterior force.
Figure 1. The apprehension test (Left) relocation test (Right) relocation test (arrow indicates the “relocating” force by the examiner).
X-rays are used to confirm a dislocation, verify the direction, and identify any fractures. Ultrasound or MRI are important if there are concerns about the rotator cuff.
Management
The first step in managing shoulder instability is prompt reduction of the dislocation. Imaging can always follow. In younger patients (17-40 years) recurrence rates after traumatic instability are high.
Reduction
The traction/countertraction technique is a commonly used method for reduction and is the most practical to perform on the sidelines immediately after an injury. This technique is performed by placing longitudinal traction on the injured arm and slowly abducting and externally rotating the arm. An assistant may be helpful for applying countertraction with a towel or similar around the athlete’s torso and pulling in the opposite direction. Once the arm is abducted the humeral head will often reduce (Figure 2).
Figure 2. Reduction manoeuvre for traumatic anterior dislocation.
Non-operative care
If immobilisation is considered, place the arm in external rotation using an external rotation pillow or brace for three weeks, both for day and night. Placing the shoulder in external rotation will force the Bankart lesion to re-appose to the glenoid neck 2. Do not use a traditional sling 3. Placing the arm in internal rotation will open the Bankart lesion and increase recurrence rates 4.
Figure 3. Following an anterior dislocation, if the shoulder is placed in internal rotation the Bankart lesion is made worse. If it is placed in internal rotation the Bankart tear is re-apposed.
Surgical repair
The techniques and technology for repairing Bankart lesions have advanced considerably. The detached labrum can now be reattached using suture anchors, which embed in the bone. The attached sutures are then passed through the labrum and capsule to secure it to the anterior and inferior glenoid margins 5. This procedure can be performed arthroscopically under local anesthesia as an outpatient surgery, resulting in minimal morbidity.
Figure 4. Schematic illustration of a reattached labral tear with suture anchors.
Written by Prof George Murrell from George Murrell Shoulders.
Professor George Murrell loves to diagnose, image and treat all shoulder conditions. He has state-of-the-art on-site x-ray and ultrasound facilities, and performs arthroscopic/keyhole shoulder surgery with the great team at Kogarah Private Hospital Sydney.
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References
1. Tzannes A, Paxinos A, Callanan M, Murrell GAC. An assessment of the inter-examiner reliability of tests for shoulder instability. J Shoulder Elbow Surg. 2004;13(1):18-23.
2. Itoi E, Sashi R, Minagawa H, Shimizu T, Wakabayashi I, Sato K. Position of immobilization after dislocation of the glenohumeral joint. A study with use of magnetic resonance imaging. J Bone Joint Surg Am. 2001;83-A(5):661-667.
3. Murrell GAC. Treatment of shoulder dislocation: is a sling appropriate? Medical Journal of Australia. 2003;179:370-371.
4. Itoi E, Hatakeyama Y, Sato T, Kido T, Minagawa H, Yamamoto N, Wakabayashi I, Nozaka K. Immobilization in external rotation after shoulder dislocation reduces the risk of recurrence. A randomized controlled trial. J Bone Joint Surg Am. Oct 2007;89(10):2124-2131.
5. Millar NL, Murrell GAC. The effectiveness of arthroscopic stabilisation for failed open shoulder instability surgery. J Bone Joint Surg (Br). 2008;90-B:745-750.