Posterolateral rotatory instability is the most common pattern of elbow instability, particularly that which is recurrent. Posterolateral rotatory instability develops when the  lateral collateral ligament (LCL) has been injured, either as an isolated sequale of elbow trauma, as part of a terrible triad injury, or as  a complication of  prior surgery such as tennis elbow debridement or following radial head repair or replacement ( if the LCL is cut).

Patients typically present with a history of recurrent painful clicking, snapping, clunking, or locking of the elbow and careful examination reveals that this occurs in the extension portion of the arc of motion with the forearm in supination. The most sensitive provocative test is the the lateral pivot-shift test, performed with the elbow is supination as an axial and valgus stress is applied moving from extension to flexion. In supination, and with valgus stress, the forearm externally rotates, pivots on the intact MCL, and subluxates posteriorly. This results in a visible dimple laterally. 

Surgical treatment may involve tightening a stretched LCL or reconstruction using tendon graft or allograft. Though the original technique described the use of bone tunnels, newer tenodesis screws allow fixation without relying on tunnels.  Postoperatively, a splint immobilizes the elbow in 90 degrees for 3 weeks at which time therapy begins.

 

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