Testing the distal tibiofibular syndesmosis – comment 3

Abstract

The intra-operative diagnosis of syndesmotic ligament rupture is problematic. Neither plain radiography1 or clinical testing is completely reliable.2,3 As the authors point out, fibular translation in the coronal plane correlates poorly with diastasis when using the hook test. Candal-Couto et al.4 demonstrated that translation in the sagittal plane was more significant than movement in the coronal plane after sequential division of the three syndesmotic ligaments in the cadaveric model (8.8 mm vs 1.5 mm). This suggests that intra-operative anteroposterior stressing rather than mediolateral stressing with the hook is a more sensitive test of syndesmotic failure. Why then do the authors advocate testing their technique in the coronal plane? A further point of note is that this technique of pushing the tibia medially away from the fibula along the 3.5-mm tap will rely upon the patient having sufficient bone quality. In the osteoporotic patient, the tap may subside into the lateral cortex of the tibia and/or lose grip in the fibula, thus preventing analysis of the syndesmosis. If one wished to stress the syndesmosis in the sagittal plane with this technique, movement would be limited (and the surgeon falsely re-assured) by contact with the tip of the 3.5-mm tap against posterior aspect of the anterior tibial tubercle. Perhaps if the tap was inserted flush with the medial cortex of the fibula then stressed in the sagittal plane, the technique would be more reliable?