In this article, orthopedic surgeons from an orthopedic center and a university review the diagnosis and treatment of humeral avulsion glenohumeral ligament (HAGL) lesions. What are HAGL lesions, you say?
The word humeral tell us the shoulder is involved because the humerus is your upper arm bone. At the top of the humerus is the round ball that fits into your shoulder socket and makes all those circular arm movements possible. Avulsion of tendons or ligaments means there has been a tearing of the soft tissues — enough to pull away from the bone where it was attached.
The glenohumeral ligament is a band of tissue around the shoulder that provides the stability needed to keep the head of the humerus in the socket. Age-related degeneration and trauma (injuries) that damage this ligament can result in a chronically dislocating shoulder.
Recognizing that a patient has a humeral avulsion of glenohumeral ligaments (HAGL) is a key to successful treatment of shoulder instability. In many cases, a patient with a shoulder that frequently pops out of the joint has more than one type of damage to the soft tissue structures. If the HAGL lesion goes undetected, surgery to treat other problems may not be successful.
How does the surgeon diagnose the problem? There are several steps in the diagnostic process. First, the surgeon asks the patient all about how this happened, what the symptoms are, and what makes it better or worse. A very important piece of patient history is a prior failed shoulder surgery.
HAGL tears occur most often when the person has the arm in a position of abduction (away from the body) and external rotation (outward rotation). Think of a pitcher’s arm after the wind-up and just before releasing the ball or how you would hold your hand under your head when lying on the ground looking up at the stars. Force or trauma with the arm and hand in this position cause avulsion injuries of the soft tissues leading to dislocation.
Clinical tests are carried out to give the surgeon an idea of the joint motion and muscle strength (or weakness). The surgeon will challenge the shoulder in different positions and directions. These tests are called provocative maneuvers.
This step helps identify which muscles, tendons, and ligaments might be affected. The direction of instability is determined through these tests. The shoulder can have multidirectional instability meaning it is unstable (dislocates) in more than one direction — forward, backward, upward, and/or downward.
X-rays and other imaging studies such as MRI and magnetic resonance arthrography (dye injected into the joint before the MRI) are essential. These tests give the surgeon a look inside to see what is going on.
An even better diagnostic test is the arthroscopic exam where the surgeon inserts a long, thin needle into the joint. There’s a tiny TV camera at the end of the scope that gives an inside view of the joint. The surgeon can see where the ligament attaches and look for any places along the rim of the socket or joint capsule where the soft tissue has pulled away from the bone.
Because the glenohumeral ligament surrounds the joint, it can be damaged in the front of the shoulder (anterior), back of the shoulder (posterior) or above (superior) or below (inferior) the joint. Treatment (usually surgical repair) is based on the location, type, and extent of damage to this ligament.
Specifics of surgical repair are provided in this article. The surgeons describe the patient position used during surgery. They include the type of incisions made and offer a step-by-step approach to surgical stabilization for HAGL lesions. Photos are shown taken during the arthroscopic exam.
The actual surgical procedure may be done following the arthroscopic exam. Sometimes it is necessary to perform and open incision repair. The details of anatomy, repair of the lesion(s), and ways to avoid cutting the subscapularis tendon are also provided.
The authors conclude by saying that the most important aspect of diagnosing and treating shoulder instability is to make sure the surgeon looks for more than one area of damage or injury.
Humeral avulsion of glenohumeral ligaments (HAGL) can go undetected when the torn edge of the ligament scars down to the joint capsule. If this lesion isn’t repaired, the shoulder will remain unstable. Repeated dislocations even after surgery to correct some other problem (e.g., torn labrum, avulsion of tendon, rotator cuff tears) is an indication of an HAGL lesion.