Lateral Ankle Avulsion Fracture Versus Subfibular Ossicles in Pediatric Lateral Ankle Sprain: A Novel Dynamic Ultrasonographic Technique.

Background: Differentiating lateral ankle avulsion fractures from subfibular ossicles in pediatric ankle sprains remains diagnostically challenging with conventional radiography. This study evaluates a novel dynamic ultrasonography technique for reliable differentiation, offering clinicians a rapid, accurate diagnostic tool.

Methods: We collected radiographic and dynamic ultrasound imaging data from 95 children with lateral ankle sprains, all of whom underwent examination using the novel dynamic ultrasonographic technique. Four observers with varying levels of clinical experience evaluated the images. Each observer made diagnoses based on radiographs alone and then in combination with dynamic ultrasound images. Interobserver reliability was assessed using the multirater free-marginal kappa, while intraobserver reliability was evaluated using the linear weighted kappa. The changes in diagnoses of the observers after the addition of dynamic ultrasound images were collected and analyzed.

Results: The study of 95 cases identified 5% (5/95) subfibular ossicles, 16% (15/95) distal fibular avulsion fractures, 4% (4/95) lateral process talus fractures, and 75% (71/95) radiographically negative cases. Among the 24 radiographically positive cases, initial interobserver agreement for distinguishing subfibular ossicles from avulsion fractures was slight (κ=0.33) using radiographs alone, which improved to excellent (κ=0.89) with dynamic ultrasound images. Ultrasound prompted diagnostic changes in 26% of cases (6.25 cases) from subfibular ossicles to avulsion fractures, and 6% (1.5 cases) from avulsion fractures to subfibular ossicles.

Conclusion: The dynamic ultrasonographic technique accurately differentiates between lateral ankle avulsion fractures and subfibular ossicles in pediatric lateral ankle sprains. This dynamic ultrasound technology can also be used to assess the stability of lateral ankle bone fragments, providing valuable information for treatment planning.

Level of evidence: Level III-diagnostic study.