The Impact of Distal Tibiofibular Syndesmosis Microinstability on Functional Outcomes in Patients With Anterior Talofibular Ligament Injury Surgery
Pengtao Shi, Yu Wei, Mengheng Liu, Shengxuan Li, Chen Yang, Zhidong Zhao, Qi Quan, Yanpeng Zhao, Min WeiBackground:
Distal tibiofibular syndesmotic injury commonly accompanies lateral ankle instability. Although a dynamic diastasis of 2 to 3 mm is traditionally considered unstable, subtler widening (<2 mm) may also occur. The clinical significance of untreated syndesmotic microinstability remains unclear.
Purpose:
To evaluate whether untreated distal tibiofibular syndesmotic microinstability affects postoperative outcomes after anterior talofibular ligament (ATFL) surgery.
Study Design:
Cohort study; Level of evidence, 3.
Methods:
Medical records and postoperative follow-up data were retrospectively reviewed for patients who underwent ATFL surgery with arthroscopic assessment of the distal tibiofibular syndesmosis between January 2017 and December 2023. Patients were classified into 2 groups: intact syndesmosis (group 1) and syndesmotic microinstability with dynamic diastasis <2 mm (group 2). Both groups underwent isolated ATFL surgery without syndesmotic fixation and followed the same rehabilitation protocol. Clinical outcomes were assessed preoperatively, at 12 months, and at final follow-up using the Karlsson-Peterson score, Foot and Ankle Ability Measure (FAAM), Tegner activity scale, visual analog scale (VAS) pain score, and ankle range of motion; Ankle Ligament Reconstruction–Return to Sport after Injury (ALR-RSI) was assessed postoperatively at 12 months and final follow-up. Group comparisons included effect estimates with 95% CIs and interpretation against minimal clinically important difference (MCID) thresholds.
Results:
A total of 104 patients (104 ankles; group 1, n = 80 patients [80 ankles]; group 2, n = 24 patients [24 ankles]) completed follow-up at a mean of 70.48 ± 24.41 months (range, 24-112 months). Both groups improved significantly over time. Group 1 had higher Karlsson-Peterson scores at 1 year (Hodges-Lehmann shift, 3 [95% CI, 1-5];
Conclusion:
Our study showed that distal tibiofibular syndesmotic microinstability was associated with slightly worse postoperative scores, but these differences were not clinically significant. These findings suggest limited clinical impact of syndesmotic microinstability below the conventional fixation threshold.