A new assessment for syndesmosis injury - The 'Chertsey test'

If a syndesmosis injury is not detected, or not treated appropriately, it can lead to pain and arthritis. Various techniques have been described to look for the presence of a syndemosis injury. If concern is raised regarding malreduction, the most recognised way of checking accuracy of the reduction (of the fibula into the incisura) is bilateral postoperative ankle CT scans. This not only exposes the patient to further radiation, but can normally only be done once the surgery is completed and so if adjustment is needed, this requires a further operation, encompassing further surgical risks. We developed a simple assessment, which both gives accurate intra-operative demonstration of an injury to the syndesmosis and also can check how well the fibula has been reduced (if required), without the need for further radiological investigation or surgical intervention. The objectives were to test how easy it was to perform the test and apply it to a number of different ankle fractures.

Peri-operatively, 2-4ml of contrast medium was injected into the ankle joint in cases where there was concern about injury to the syndesmosis. If there was a 'positive' test, and a 'blush' of dye leaked into the surrounding soft tissues, then fixation of the syndesmosis was performed (as per the surgeon's preferred technique). After fixation was completed, a further injection of contrast medium was injected to see if the fibular had been anatomically reduced into its incisura. The test was performed on 15 ankles.

There were no difficulties in performing the test and no complications reported. The test clearly demonstrated where there had been an injury to the syndesmosis and also confirmed the accurate reduction of the fibula when there had been stabilisation of the syndesmosis.

It has proved to be an easy and reliable adjunct to ankle fixation surgery and may have further indications.