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Figure 1: Anteroposterior view of the right shoulder after the dislocation.
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Figure 2: Shoulder after closed reduction.
A 30-year-old man presents with recurrent right shoulder pain and instability for at least 5 years. The patient is an electrician who is right-handed. He had an arthroscopic stabilization procedure for a Bankart tear 3 years ago, which initially worked well. However, over the past year, the patient has noticed more pain and instability. The patient’s right shoulder dislocated during a basketball game; he went to the emergency department and underwent a closed reduced a few hours later (Figures 1 and 2). Magnetic resonance imaging (MRI) taken at the hospital reveals a moderate Hill-Sachs lesion without evidence of capsule or ligament tear. A computed tomography (CT) scan shows 25% loss of the glenoid bony surface from an old bony Bankart lesion.
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Glenohumeral joint stability is provided by a combination of bony anatomy, joint capsule, glenohumeral ligaments, and labrum. A Bankart lesion, or an avulsion of the anterior labrum and inferior glenohumeral ligament, is the most common cause of traumatic shoulder instability. An arthroscopic repair of the Bankart lesion is the most common surgical stabilization procedure. A bony Bankart lesion, or when bone is avulsed from the glenoid, can also create glenohumeral instability. These lesions are more likely to occur with repetitive dislocation of the shoulder and the bony defects increase in size with increasing number of dislocations.1,2
The analogy of a golf ball resting on a golf tee is commonly used to describe bony stability of the glenohumeral joint. If a critical piece of the golf tee surface is removed, the golf ball will no longer rest on top. When the glenoid loses 21% to 30% of its bony surface, glenohumeral stability is reduced substantially. In younger athletes, bone loss as low as 13.5% has been associated with unacceptable joint instability.1,3 A CT scan is the imaging study of choice to quantify the percentage of glenoid bone loss.2
In patients with chronic instability and significant glenoid bone loss, a procedure to add bone to the glenoid to increase its surface area is often necessary. The most common procedure involves taking a coracoid autograft and attaching it to the glenoid. In this case, a Latarjet procedure was used to restore stability to the shoulder joint.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
References
1. Willemot LB, Elhassan BT, Vergorgt O. Bony reconstruction of the anterior glenoid rim. J Am Acad Orthop Surg. 2018;26(10):e207-e218. doi:10.5435/JAAOS-D-16-00649
2. Bencardino JT, Gyftopoulos S, Palmer WE. Imaging in anterior glenohumeral instability. Radiology. 2013;269(2):323-337. doi:10.1148/radiol.13121926
3. Sheean AJ, De Beer JF, Giacomo GD, Itoi E, Buckhart SS. Shoulder instability: state of the art. J ISAKOS. 2016;1(6):347-357. doi:10.1136/jisakos-2016-000070
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