Isolated distal radial metaphyseal fractures with an intact ulna: risk factors for loss of reduction.

PURPOSE: The purpose of this study was to determine the risk factors for loss of reduction in patients with an isolated distal radius fracture and intact ulna.
METHODS: Outpatient records and initial, post-reduction, and follow-up radiographs of children with displaced distal radial metaphyseal fractures and intact ulnas that required closed reduction and casting at our institution were reviewed for demographic factors, body mass index (BMI), initial fracture displacement, residual displacement after reduction, and 3-point cast index. Loss of reduction was defined as angulation ≥15° in the coronal plane for all ages and/or angulation ≥20° in the sagittal plane for patients ≥11 years of age and ≥30° for children <11 years of age. Additionally, all patients who were remanipulated and/or pinned were considered to have lost reduction.
RESULTS: Thirty-five of the 76 patients in our series met the criteria for loss of reduction (46%). Multivariate logistic regression revealed that initial angulation in the coronal plane and post-reduction translation in the coronal plane were independent predictors for loss of reduction. Patients with >11° of initial angulation in the coronal plane were 6.3 times as likely to lose reduction (confidence interval [CI]: 1.43-28.3, P = 0.015) and those with any amount of residual translation in the coronal plane after closed reduction were 7.8 times as likely to lose reduction (CI: 2.5-24.0, P < 0.001).
CONCLUSION: Our study, the largest dedicated series of distal radial metaphyseal fractures with intact ulnas, indicates that loss of reduction is common, and that risk factors include initial angulation in the coronal plane and post-reduction translation in the coronal plane.