Radiographic Parameters With Intraoperative Stress Tests To Detect Syndesmotic Instability In Ankle Fractures

Abstract

Introduction: Syndesmotic injuries of ankle most frequently occur due to external rotation injury or forceful abduction injury at the ankle. Frequently they are associated with Pronation-External rotation and pronation-abduction injuries, and infrequently with Supination-External rotation injuries (SER) and Supination-Adduction injuries. Although the incidence of syndesmotic injury is less in SER injuries as compared to Pronation external rotation injuries, when missed, it will lead to a chronically unstable ankle joint with chronic persistent pain and early osteoarthritis. Thus, detection of syndesmotic injuries in SER type of ankle fractures is of paramount clinical importance to prevent the morbidity to the patient.

Aim: To assess the role of fracture height, fracture length, medial joint space, fracture geometry of the medial malleolus and tibiofibular overlap as radiological parameters in prediction syndesmotic injuries

To find out the frequency of missed syndesmotic injuries in Supination-External Rotation Lauge-Hansen II and IV and Weber Type B ankle fractures

Materials & Methods: A total of 39 patients with SER injuries were included. Fracture height, fracture length, medial clear space, tibiofibular overlap and medial malleolus fracture geometry were measured preoperatively on plain radiograph. Intraoperative stress tests were performed and correlated with the measurements to detect syndesmotic injuries.

Results: In our study 12/39 (30.7%) of patients had syndesmotic injury. In our study we found that the Mean± SD of fracture height and the medial clear space in the group with syndesmotic injury was 6.43±1.61 and 6.8±0.79 respectively and Mean± SD in the group without syndesmotic injury was 5.28±1.23 and 5.03±0.68 respectively. The p value for fracture height was found to be 0.019 and that for medial clear space was 0.001 both were statistically significant.

Conclusions: This study reports that radiological parameters such as fracture height and medial clear space still hold importance in the preoperative detection of syndesmotic injuries. However these tests need to be used in conjunction with the intraoperative stress tests in detecting and the treatment of syndesmotic injuries. we can conclude that with the current available radiological parameters and the subjective nature of the intraoperative stress tests there is a high chance of missing a syndesmotic injury in SER and Weber Type B ankle fractures. There is a need for more objective and recordable findings.