Prone Push-Up Test | Posterolateral Instability
Posterolateral rotatory instability, abbreviated as PLRI is the most commonly encountered pattern of elbow instability.
PLRI typically occurs as a result of a fall on the outstretched arm, generating an axial load, valgus force, and an external rotational movement (torque) about the forearm with respect to the humerus. This causes the radial head and proximal ulna to subluxate posterolaterally away from the humerus in a rotatory fashion detaching or tearing the lateral collateral ligament complex in stage 1. In a more severe stage 2, the tissue disruption progresses anteriorly and posteriorly around the elbow to the medial side and in stage 3, the injury involves the medial collateral ligament or even the common flexor-pronator origin.
Regan et al. (2006) did a diagnostic study on the prone push-up test and found a sensitivity of 87,5% with unknown specificity. For this reason, we give this test a questionable clinical value in practice.
The push-up test makes use of the patient’s body weight to create an axial load, and valgus torque at the elbow resulting in posterolateral subluxation of the elbow. In order to perform the test have your patient lie in prone position with his chest on the floor or treatment bench with the elbows flexed at 90 degrees, the shoulders abducted and the side to be tested in supination at the forearm. Now ask the patient to perform a push-up.
This test is positive if the patient has apprehension, reports a sense of instability or lateral elbow pain or if actual dislocation of the radial head takes place.
21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE
Other common orthopedic tests for PLRI are:
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