The influence of applied internal and external rotation on the pivot shift phenomenon.

PURPOSE: The pivot shift test is performed in different techniques and the rotation of the tibia seems to have a significant impact on the amount of the pivot shift phenomenon. It has been hypothesised that external rotation will increase the phenomenon due to less tension at the iliotibial band in knee extension.

METHODS: Twenty-four patients with unilateral anterior cruciate ligament insufficiency were included prospectively. The pivot shift test was performed bilaterally in internal and external tibial rotation under general anaesthesia. Knee motion was captured using a femoral and a tibial inertial sensor. The difference between positive and negative peak values in Euclidean norm of acceleration was calculated to evaluate the amount of the pivot shift phenomenon.

RESULTS: The pivot shift phenomenon was significantly increased in patients with ACL insufficiency when the test was performed in external [mean 5.2 ms(- 2) (95% CI 4.3-6.0)] compared to internal tibial rotation [mean 4.4 ms(- 2) (95% CI 3.5-5.4)] (p = 0.002). In healthy, contralateral knees did not show any difference between external [mean 4.0 ms(- 2) (95% CI 3.3-4.7)] and internal tibial rotation [mean 4.0 ms(- 2) (95% CI 3.4-4.6)] (ns).

CONCLUSIONS: The pivot shift phenomenon was increased with external rotation in ACL-insufficient knees, and therefore, one should perform the pivot shift test, rather, in external rotation to easily evoke the, sometimes difficult to detect, pivot shift phenomenon.

LEVEL OF EVIDENCE: I (diagnostic study).