Direct visualization of the syndesmosis for evaluation of syndesmotic disruption: A cadaveric study

Objectives: Radiologic criteria for syndesmosis instability evaluation remain controversial and direct visualization (DV) of the distal tibiofibular articulation is an alternative diagnostic method worthy of further investigation. We speculate that DV is a more accurate way to evaluate syndesmosis instability than fluoroscopy. The purpose of this study is to determine whether syndesmosis instability can accurately be recognized through DV and if this new intraoperative diagnostic method is more sensitive than fluoroscopy in detecting syndesmosis instability.

Methods: Ten cadaveric ankles were tested using a sequential iatrogenic syndesmosis injury model. Specimens were tested incrementally with the lateral stress test (LST) and the external rotation stress test (ERT). The resulting instability was measured directly and fluoroscopically with a true mortise view by using medial clear space (MCS) and tibiofibular clear space (TFCS).

Results: DV detected a 2-ligaments injury at a mean diastasis of 3.02 mm (P = 0.0077) and 3.19 mm (P = 0.0077) with the LST and ERT, respectively. Fluoroscopically, TFCS showed a significant diastasis only with a complete syndesmosis rupture while MCS did not show any significant differences.

Conclusions: DV of the syndesmosis in a cadaver injury model appears to be more sensitive than fluoroscopy in identifying injury, especially incomplete syndesmotic disruption.