Review Question - QID 974

The aforementioned tests help in diagnosing syndesmotic injuries. For an external rotation stress test, the knee is flexed 90 degrees and the ankle is in neutral. Stabilizing the tibia and fibula with one hand, the examiner externally rotates the ankle with the other. Widening of the syndesmosis indicates a positive test. This test method has been recently shown to have the fewest false-positive results and most accurate diagnostic abilities.

The lateral stress test, or Cotton test, has previously been shown to have the least false positive results in an acute syndesmotic injury. In the Cotton test, the fibula is attempted to be pulled laterally, and widening of the syndesmosis would therefore indicate syndesmosis injury.

Beumer et al. tested the squeeze, fibula translation, Cotton, and external rotation tests. None of the syndesmotic tests was uniformly positive in chronic syndesmotic injury. The fibular translation test had the most false-positive results.

Stoffel et al. performed a cadaveric study that found that the Cotton test produced a significantly greater increase in the tibiofibular clear space than did the external rotation test for Weber C injuries and Weber C plus deltoid ligament injuries. A greater increase in the tibiofibular clear space was noted during the lateral stress test when both the deltoid and the anterior inferior tibiofibular ligament had been sectioned.

Matuszewski et al. presented a prospective series of 28 patients undergoing ankle fracture fixation and compared intraoperative testing methods of the syndesmosis. They reported that compared with the Cotton test, stress external rotation demonstrated a 35% increase in medial clear space widening.

The video is an example of the Cotton test for evaluation of syndesmotic instability.