2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Syndesmal Instability Evaluation Under WBCT: 3Rd Base to Get a Cut-Off Point to the Diagnosis

Nicolas Protasowicki, MD, Nunoa, METROPOLITANA CHILE
Manuel Jose Pellegrini, MD, Santiago De Chile, Santiago de Chile CHILE
Giovanni Carcuro, MD CHILE
Felipe Chaparro Ravazzano, MD, Santiago de Chile, Metropolitana CHILE
Cristian ALEJANDRO Ortiz, MD, Santiago, Region Metropolitana CHILE
Giovanni Carcuro, MD CHILE

CLINICA UNIVERSIDAD DE LOS ANDES, LAS CONDES, METROPOLITANA, CHILE

FDA Status Cleared

Summary

19% difference in the syndesmal area between the uninjured and injured ankles should be used as the cut-off point to suspect syndesmal instability

Abstract

Because costs and risks associated with arthroscopy are present, objective non-invaisve criteria to provide an accurate preoperative diagnosis of syndesmotic instability are needed. Comparative WBCT is a valuable tool for assessing syndesmal symmetry. Specifically, the difference in the syndesmotic area correlates with diastasis at the inferior tibiofibular joint, while the cut-off value for diagnostic instability remains undetermined. Our bbjective is to compare differences in the syndesmotic area between uninjured subjects and patients with syndesmotic sprains under WBCT.

Patients with suspected syndesmotic injuries between 14 and 60 years old were included as case group. The control group was obtained from a previous WBCT comparative study for reasons other than instability. The percentage difference between the injured and uninjured sides was calculated using comparative monopodial WBCT.

Results

Thirty-eight patients in the study group and twenty-four in the control group were included. Arthroscopy was indicated in 6/38 (15.8%) patients, confirming the diagnosis of syndesmal instability. The remaining patients in the study group were classified as stable injuries. The mean percentage area difference from confirmed syndesmal instability, stable syndesmosis injuries, and uninjured ankles were 19.7% (IC 13.2-26.1), 6.8% (IC 0.6-12.9), and 1.46% (IC 0.98-1.94) (p=0.008). The area under the curve was 0.863, with sensitivity, specificity, and positive and negative predictive values of 83.3%, 89.3%, 45.5%, and 98.0%, respectively.

Conclusion

Comparative WBCT demonstrated usefulness in determining stability in suspected syndesmotic injuries. Despite the limitations of this study, our results suggest that a 19% difference in the syndesmal area between the uninjured and injured ankles should be used as the cut-off point to suspect syndesmal instability.