What is the Effect of Lateral Ankle Ligament Injury on Syndesmotic Stability? Arthroscopic evaluation

CATEGORY: Ankle; Arthroscopy; Sports; Trauma INTRODUCTION/PURPOSE: Numerous studies have shown a high incidence of associated lateral ankle and syndesmotic ligamentous injuries. It is unclear, however, if there is a direct contribution of the lateral ligaments towards stabilizing the syndesmosis. Using arthroscopy, we assessed to what extent lateral ankle ligaments contribute to syndesmotic stability in the coronal and sagittal plane. Our hypothesis was that lateral ankle ligament injury has effect on syndesmosis instability. METHODS: Sixteen fresh frozen above-knee amputated cadaveric specimens were divided into two groups that underwent arthroscopic evaluation for syndesmotic stability. In both the groups, the assessment was done with all syndesmotic and ankle ligaments intact and later with sequential transection of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), the posterior talofibular ligament (PTFL), anterior inferior tibiofibular ligament (AITFL), the interosseous ligament (IOL) and the posterior inferior tibiofibular ligament (PITFL). In all scenarios, coronal and sagittal loading conditions were considered under 100N of direct force to fibula. The measurements of the distal tibiofibular coronal plane space at the anterior and posterior third of syndesmosis were performed using arthroscopic probes with increment of 0.2mm diameter. Further the sagittal translation were measured by arthroscopic scaled probe. Dunnett test was used to compare the findings of each ligamentous transection state to the intact state. A p-value < 0.05 was considered significantly defferent. RESULTS: Compared with the intact ligamentous state, there was no difference in coronal and sagittal stability when the lateral ankle ligaments (ATFL, CFL, PTFL) and AITFL were transected (Table1 and 2, Group1). However, after subsequent transection of the IOL, or after transection of the lateral ankle ligaments (ATFL, CFL or and PTFL) alongside the AITFL and IOL, both coronal space and sagittal translation increased as compared with the intact state (p-values p<0.001 respectively) (Table1 and 2, Group2). CONCLUSION: Our findings suggest that lateral ankle ligaments do not directly contribute to syndesmotic stability in the coronal and sagittal plane. In concomitant acute syndesmotic and lateral ligament injury, surgeons should pay attention to whether there is combined IOL injury to determine the fixation of syndesmosis.