Predictors of Osteochondral Fractures Following Patellar Dislocation in the Pediatric Emergency Department.

BACKGROUND

Patellar dislocations are frequently seen in the emergency department (ED). Almost all children with a reduced patellar dislocation will have a knee radiography, while only 10% have a fracture identified on x-ray.

OBJECTIVE

The primary purpose of the study was to identify factors predicting osteochondral fractures among children with patellar dislocation reduced in the ED.

METHODS

This was a retrospective cohort study of all children aged between 1 and 18 years old with patellar dislocation who needed a reduction in a tertiary care pediatric ED between 2019 and 2024. The primary outcome was the presence of a fracture identified by radiology (x-ray or MRI) during ED visit or follow-up at the orthopedic clinic. Multiple independent variables were evaluated as potential predictors. These were related to the patient (age, sex, previous patellar dislocation), the accident, and the physical examination before and after reduction, as well as finding at the follow-up at the orthopedic clinic. All charts were evaluated using a standardized form, and 10% were evaluated in duplicate to ensure interrater reliability. The primary analysis was the association between the independent variable and fracture using logistic regression.

RESULTS

There was a total of 316 diagnoses of patellar luxation in 276 children with a median age of 14 years. Ninety-six children had their patellar dislocation reduced at the ED and were included in the study, of whom 19 (20%) had a fracture. Of all variables tested, only the persistence of knee swelling at orthopedic follow-up was associated with a higher risk of fracture (OR: 13.39; 95% CI: 1.70-105.32).

CONCLUSION

Approximately 20% of children who needed a reduction in the ED for patellar dislocation had a fracture. Persistent knee swelling at follow-up is a potential predictor of fracture.