Point-of-Care Ultrasound Evaluation of Ankle Injuries in Children

Objectives To determine if point-of-care ultrasound (POCUS) of ankle injuries in children, in conjunction with validated ankle injury clinical prediction rules, can accurately diagnose ankle fracture in children. Methods A prospective observational study was conducted on patients (birth-21 years) presenting to a pediatric emergency department with an ankle injury requiring ankle radiograph. POCUS of the injured ankle was performed to evaluate for fracture. Clinical prediction rule scores (Ottawa Ankle and Low Risk Ankle) were recorded along with pre- and post-ultrasound clinical suspicion for fracture. Diagnosis of ankle fracture was confirmed via radiology radiograph report. Test characteristics of sensitivity, specificity, positive and negative predictive values were calculated. Results Forty-eight patients were enrolled, 58% were female, with a mean age of 12.2 years (SD 3.8). Twelve (25%) patients had ankle POCUS positive or indeterminate for fracture. Nine (19%) patients had fracture based on radiograph, and 6 of the 9 (67%) patients with fracture had open growth plates. Ankle POCUS was found to have a sensitivity of 56% (95% confidence interval [CI], 23-85%), specificity of 82% (95% CI, 66-92%), positive predictive value of 42% (95% CI, 17-71%), and negative predictive value of 89% (95% CI, 73-96%). Conclusions Our findings suggest that ankle POCUS in children is a difficult application to perform and interpret compared with radiographic diagnosis of fracture. Open growth plates may complicate accurate identification of fracture using POCUS and at this time serves as a poor screening exam to assess for fracture or the need for radiographs.