Avulsion fracture of the distal fibula is associated with recurrent sprain after ankle sprain in children

PURPOSE: The purpose of this study was to clarify radiographic and clinical outcomes, as well as their association, of ankle sprain in children. METHODS: Patients who sustained a first-time ankle sprain were prospectively surveyed. Patients underwent radiography of the ankle in the mortise, lateral, anterior talofibular ligament (ATFL), and calcaneofibular ligament views at the first clinic visit to assess avulsion fractures of the distal fibula. Patients with avulsion fractures underwent radiography after 8 weeks to assess bone union. The treatment method was not standardized and was determined by the patient, their parents, and the treating physician. Recurrent sprain and quality of life were evaluated by using the Self-Administered Foot Evaluation Questionnaire and reviewing the medical records of patients. The association between avulsion fracture and recurrent sprain was assessed using univariate and multivariate analyses. RESULTS: A total of 143 patients with a median age of 9 (range 6-12) years were analyzed. Avulsion fractures were present in 89 (62%) patients. The sensitivity of the ATFL view for the diagnosis of avulsion fractures was 0.94, whereas that for the anteroposterior and lateral views was significantly lower at 0.46 (P < 0.001). Only 17% of fractures united at 8 weeks. Of 114 (follow-up rate, 80%) patients who were followed up for a median period of 24 months, recurrent sprain occurred in 41 (36%) patients. The incidence rate was significantly higher in patients with avulsion fractures than in patients without the fractures (44 vs. 23%, P = 0.027). In multivariate logistic regression analysis, avulsion fracture was independently associated with recurrent sprain (P = 0.027). CONCLUSION: More than one-third of patients experienced recurrent sprain. The presence of avulsion fracture was associated with an increased risk of recurrent sprain. Patients with avulsion fracture and their parents should be informed about the risk of recurrent sprain and subsequent ankle instability, and careful follow-up is needed for these patients. LEVEL OF EVIDENCE: III.