Background: Avulsion fractures of the lateral malleoli in ankle inversion injuries are often undetected on routine radiographs. Undetected avulsion fractures have been managed as ankle sprain, which may affect the outcome of the treatment of the ankle sprain. The purposes of this study are to compare the outcomes of functional treatment between the first-time severe ligament injury and avulsion fracture of the lateral ankle, and to investigate how the anterior talofibular ligament (ATFL) view or the calcaneofibular ligament (CFL) view affects the diagnosis of the avulsion fracture and outcome of functional treatment of the ankle inversion injury.
Methods: A total of 276 consecutive patients with a first-time severe ankle inversion injury were classified into a ligament injury group (group I) or an avulsion fracture group (group II) on the basis of physical examination and radiographs. The patients with a negative finding on routine radiographs and a positive finding on the ATFL or CFL view derived from group II (group IIA). Age, sex, and activity level were analyzed. Patients were treated by stirrup splint.
Results: A total of 202 (73.2%) patients were in group I and 74 (26.8%) were in group II. In all, 50 patients in group II showed negative standard radiographs and a positive ATFL or CFL view. Altogether, 240 patients were followed up for at least 1 year and assessed clinically and radiographically. Differences in age, sex, and activity level before injury between groups were not statistically significant. Clinical and radiographic results of group II were inferior to those of group I. The outcome of group IIA was comparable to that of group I.
Conclusions: The outcome of functional treatment of avulsion fracture was inferior to that of ligament injury. The ATFL and CFL views provide a more precise diagnosis but do not affect the outcome of the functional treatment.