Elbow Resources

Elbow instability (R)(M) Elbow instability (R)(M)


Introduction
There are two types of instability; lateral vs. medial, and the two are quite different. MCL insufficiency is a repetitive strain injury usually seen in throwing athletes, whereas LCL insufficiency usually follows a fall.
MCL insufficiency is dealt with in the section on the throwing athlete.

Lateral ulnar collateral insufficiency
Recurrent instability resulting in joint subluxation or recurrent dislocation is usually due to LUCL insufficiency

Epidemiology
The five patients in O'Driscoll's original article ranged from 5-46 years old.

Aetiology
Fall onto outstretched hand.
Four out of five patients in O'Driscoll's original series had an elbow dislocation.
Iatrogenic following lateral approach to elbow for radial head fracture or tennis elbow.

O'Driscoll's concept of instability
Instability can be thought of as a circle of soft tissue disruption from lateral to medial, occurring in 3 stages.
• Ulnar part of LCL is disrupted resulting in PLR subluxation (PLRI), which self reduces.
• The disruption extends medially, both posteriorly and anteriorly, but not involving the MCL. This permits incomplete dislocation, with the coronoid process perched in the trochlear groove
• 3A: All structures around to and including the posterior bundle of the MCL are disrupted, permitting posterolateral rotatory dislocation. The intact anterior bundle of the MCL provides valgus stability, and the elbow is stable as long as the arm is pronated.
3B: The entire MCL is disrupted. The elbow remains unstable in extension.

Clinical
Patients complain of giving way, or have episodes of subluxation during pushups or lifting with outstretched hand.
Lateral pivot shift test of elbow (O'Driscoll 1991): The patient lies supine, with the shoulder elevated to around 150 degrees, and fully externally rotated. The forearm is supinated to face down. The elbow is axially compressed while a valgus force is applied. The elbow is progressively flexed from a position of full extension. In extension the joint is reduced; as it flexes it subluxes, then at around 40 degrees of flexion it reduces with a clunk. The test is positive if the patient experiences apprehension, or there is a feeling of reduction (O'Driscoll says this test is best done with the patient anaesthetized). If the forearm is held pronated, there will be no subluxation.

Imaging
Can do stress XR to look for posterolateral subluxation (i.e. posterior subluxation of the radiohumeral joint and gaping of the ulnohumeral joint).
MRI

Treatment
In acute cases, where the ligament complex is avulsed from the humerus, the ligament can be fixed back at the axis of rotation.
In chronic cases, a reconstruction with palmaris longus or plantaris is required. The insertion onto the lateral epicondyle must be isometric. The posterolateral and anterolateral capsule is reefed and imbricated. The insertion point onto the ulnar is just posterior to the tubercle of the supinator crest.
The sutures are tied and the graft tightened with the arm flexed to 30 degrees and held in pronation.
Postoperatively the elbow is immobilized at 90 degrees and full pronation for 3 weeks, then a hinged brace with a 30 degree extension block is applied for 6-9 weeks or longer, depending on the degree of ligamentous laxity.
Return to sport is allowed at 6 months.

Results
Successful stabilization often leads to a slight flexion contracture (20 degrees).
In most published series, over 80% of patients achieve a stable elbow and return to activity with minimal loss of motion.

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