Elbow instability refers to a rupture or stretching out of one of the main ligaments that keeps the elbow from dislocating or subluxing (“partial dislocation”). This may occur following trauma or as a result of repetitive stress and strain to the ligament. Often, instability is not obvious to the patient but rather manifests as pain or a decrease in athletic performance (such as loss of pitch speed and endurance in a throwing athlete). Rarely, patients are able to actually pop the elbow out of joint, and have had a history of dislocating the elbow in the past. There are several types of elbow instability but the two most commonly treated ones are:

  • Posterolateral Rotatory Instability (PLRI)
  • Valgus Instability

 
 

Posterolateral Rotatory Instability (PLRI)
Posterolateral Rotatory Instability of the elbow (PLRI) is caused by failure of the lateral ulnar collateral ligament (LUCL) of the elbow, resulting in pain in the outer back side of the elbow (posterolateral elbow). This may be caused by a prior elbow fracture or dislocation. Rarely, it may also happen after surgery or too many cortisone injections for tennis elbow. Patients usually feel pain at the posterolateral elbow, and may also have difficulty “locking out” the elbow because of a sense that the elbow may pop out of joint when it is held in a fully straightened position. Very rarely can patients cause the elbow to come out of joint on purpose. Physical exam is not usually reliable in picking up this diagnosis, unless a stress exam of the elbow under anesthesia is performed. Xrays are used to rule out other conditions (fractures, arthritis, loose bone chips in the joint). An MRI may even miss the diagnosis in mild cases.

When the condition is acute (within a few months following an elbow dislocation) it may be treated by keeping the arm in a long cast for about a month, followed by supervised physical/occupational therapy. If the condition has persisted for more than a few months then surgery is almost always required. This is usually in the form of a ligament reconstruction, in which a cadaver tendon or a wrist tendon (the palmaris longus) from the patient is harvested and used to recreate the lost ligament. Elbow arthroscopy is often performed at the same time if other conditions are suspected.

Case Example:
A 56 year old woman with a history of multiple prior cortisone injections and surgery for treatment of right tennis elbow presents with dull aching posterior lateral elbow pain which is aggravated by trying to fully extend or “lock out” the elbow. MRI demonstrated obvious rupture of the lateral ulnar collateral ligament (LUCL). Therefore, open ligament reconstruction was performed due to significant difficulty using the arm despite rest and physical therapy. Arthroscopy was not needed to assist in the diagnosis here. After much postoperative physical therapy she became pain free with full motion and no instability of the elbow.

MRI showing ruptured lateral ulnar collateral ligament of the elbow (LUCL) Intraoperative photograph showing lateral ulnar collateral ligament (LUCL) reconstruction
MRI of the elbow Intraoperative view following reconstruction of ligament.

 
 

Video: Arthroscopic diagnosis and treatment of an unstable elbow

Following successful ligament reconstruction, the patient will need to be placed into a long arm cast for 3-4 weeks to allow healing of the tendon graft. This is then followed by 6-8 weeks of controlled, protected physical or occupational therapy. By 12 weeks after the surgery patients are allowed full return to activity if they are doing well. The vast majority of patients with PLRI do very well from such a ligament reconstruction.

 
 

Valgus Instability
Injury to the medial ulnar collateral ligament causes Valgus Instability, making the elbow unstable. This often happens in trauma or as a result from overuse during sports, particularly in overhead throwing athletes such as pitchers, quarterbacks, and javelin throwers. Most injuries occurring in non-professional athletes are successfully treated with a period of complete rest from throwing, followed by physical therapy and a gradual return to throwing. Occasionally, if the athlete is unable to return to a high level of competition, then ulnar collateral reconstruction (“Tommy John” surgery) is performed. The procedure is in many ways very similar to the reconstruction surgery of the lateral ulnar collateral ligament described above. Rehabilitation usually involves a 3 week period in a cast, followed by several months of stretching and strengthening. Gradual return to overhead throwing resumes approximately 4 months following surgery, with expected return to competitive throwing anywhere from 9-12 months postoperatively. Between 60-90% of throwing athletes are able to return to their preoperative level of throwing speed and endurance following successful rehabilitation from Tommy John surgery.