This is the first article in a two-part series on elbow instability injuries. Dislocation and joint laxity (looseness) on either side of the elbow are common with elbow instability. Proper diagnosis is needed in order to plan the best treatment approach. In this article, elbow anatomy and biomechanics are reviewed to help with the diagnostic process.
The elbow is a complex hinge joint. Three bones come together at the elbow to create elbow flexion and extension. There are ligaments, muscles, and other soft tissue restraints holding the joint together. Traumatic or overuse injuries that disrupt any of those structures can result in elbow instability.
The structures around the elbow must provide a stable position of the joint no matter what position it’s in. Forces exerted on the elbow during a dislocation can result in significant loss of stability. The medial collateral ligament (MCL) on the inside of the elbow (closest to the body) and the lateral collateral ligament along the outside of the elbow create a capsule around the joint.
Both of these ligaments are made up of several bundles or bands of tissue that resist stress through the joint. If enough force is exerted on the ligaments, dislocation can occur. After elbow dislocation, the surgeon must evaluate the strength and integrity of these two ligaments.
Special stress tests can be performed. Testing procedures for each of these ligaments are presented. Symptoms of medial instability for the MCL and lateral instability for the LCL are also reviewed.
The most common symptoms are pain and tenderness along the inside (or outside) of the elbow. Symptoms occur with overhead throwing activities. Pressure on the nerves through the elbow can also result in numbness and tingling down the arm or into the hand and fingers. With lateral instability, there may be a painful clicking, catching, or snapping sensation. It feels as if the elbow is slipping in and out of the joint.
Stress radiographs (X-rays) can be used to show gaps in the joint. This is a sign that the soft tissues are insufficient. This means they aren’t strong enough to hold the joint and prevent future instability. MRIs with an injected dye are used to make the diagnosis of a partially torn or completely ruptured ligament.
Elbow dislocation doesn’t always mean surgery is needed. Once the physician identifies the soft tissue structures that were damaged, a specific treatment plan can be determined. Part-two of this article series will provide more details on conservative (nonoperative) and surgical care of this problem.