Elbow Instability

elbow instability
Title: Complex Instability of the Elbow

Reference: Morrey, Bernard F., AAOS Instructional Course Lectures, Volume 47, 1998

Main Message

These are complex injuries. The basic principles are to first restore the ulnohumeral articulation (as this contributes most to elbow stability), then repair or replace the radial head as an important secondary stabilizer to the collateral ligaments. Finally, they protect the ulnohumeral articulation with an external fixator.

Points of Interest

Normal Stability
– the radial head can be resected in an otherwise uninjured elbow – IT IS A SECONDARY STABILIZER to the collateral ligaments. The resistance to valgus stress provided by the radial head is minimal when the MCL is intact, but when the MCL is torn, the radial head becomes important.
– the proximal ulna is the primary determinant of stability in the elbow.
– the coronoid is important, but it is not yet known how much must be present – probably at least 50% of it should be present
– ligaments provide 50% of the varus-valgus stability; the articular surfaces provide the rest; the anterior capsule is important in extension.

Radial Head Fracture with MCL Injury
– rare, but should be recognized.
– even though the MCL is the primary stabilizer and the radial head is the secondary stabilizer, the initial principle of management is to repair the radial head – either by osteosynthesis or prosthetic replacement. If the radiohumeral joint is not restored, then the MCL is fixed.

Radial Head Fracture with Elbow Dislocation (and intact ulna)
– “There is little information in the literature to help to define the optimum treatment of fracture dislocations.”
– “Stability” is defined as being stable in the arc of motion to within 45 to 50O of extension.
– Type I – posterior slab, then early ROM
– Type II – must treat the radial head, because the dislocation implies MCL injury
– Type III – excise, then direct repair of the collateral ligaments
– may consider a prosthesis, but should probably go ahead and fix the collaterals anyways. Consider using an external fixator to allow flexion yet maintain the ulnohumeral articulation.

Radial Head Fracture with Elbow Dislocation and Coronoid Fracture
– Fix or replace the radial head, then fix the coronoid, then protect it all with a hinged x-fix.

Thoughts….

Nice review. Morrey appears to use CADAVERIC replacement of the radial head. WIERD. They are really big into the hinged x-fix to protect the stability of the joint and to protect any coranoid fixation.

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