Review Question - QID 214109

The lateral pivot shift test is used to identify posterolateral rotary instability (PLRI) of the elbow. It is performed with the patient supine by flexing the elbow from full extension while applying valgus and supination moments with axial compression.

PLRI is characterized by posterolateral subluxation or dislocation of the radiocapitellar and ulnohumeral joints. It is caused primarily by insufficiency of the LUCL, often as a result of a traumatic elbow dislocation. Other causes include iatrogenic injury (i.e., arthroscopic debridement) and chronic attenuation (i.e., chronic cubitus varus malunion). Several provocative tests have been described in addition to the lateral pivot shift test. These include the posterolateral rotatory drawer, prone push-up, chair push-up test, and table-top relocation tests. Standard radiographs are often normal but may show an impaction defect of the posterolateral capitellum. Additional examination techniques include dynamic testing aided by fluoroscopy or stress radiographs, which may demonstrate subluxation of the radiocapitellar and ulnohumeral joints.

Mehta et al. reviewed posterolateral rotatory instability of the elbow. The authors note PLRI is a three-dimensional displacement pattern that causes the radius and ulna to displace into external rotation and valgus with elbow flexion. The radial head subluxates posterior to the capitellum while remaining secured within the sigmoid (radial) notch by the annular ligament. They conclude the test is best performed under fluoroscopy or general anesthesia and instability is managed with either repair or isometric reconstruction of the LUCL.

Smith et al. describe tests and anatomical correlations in their comprehensive review of the elbow physical examination. They note rotatory displacement is maximized at approximately 40º of flexion when performing the lateral pivot shift test. In an anesthetized patient, a positive test will demonstrate a palpable and visible clunk along with a posterior prominence and dimpling as a result of a dislocated radial head. Further flexion results in joint reduction.

Video 1 is an example of how to perform the lateral pivot shift test.

Incorrect Answers
Answer 1: Disruption of the posterior band of the MCL is a component of varus posteromedial rotatory instability (VPMRI).
Answer 2: The posterior capsule contributes to the stability of the elbow. However, disruption does not lead to PLRI.
Answer 4: The anterior band of the MCL is the primary restraint to valgus stress, injury can result in valgus instability.
Answer 5: The transverse ligament of Cooper consists of fibers running from the coronoid process to the olecranon and has no contribution to elbow stability.