Main Outcome Measurements: Failure of nonoperative management, defined as conversion to surgery, malunion, and delayed union/nonunion.Results: Nonoperative management failed in 33 (31%) of 106 included patients with 27 patients (25%) requiring surgery. On multivariate analysis, female sex [odds ratio (OR): 3.50, 95% confidence interval (CI): 1.09 to 11.21], American Society of Anesthesiologist classification .1 (OR: 7.16, CI: 1.95 to 26.29), initial fracture medial/lateral (ML) translation (OR: 1.09, CI: 1.01 to 1.17, per unit change), and initial fracture anterior-posterior (AP) angulation (OR: 1.09, CI: 1.02 to 1.15, per unit change) were independently associated with failure of nonoperative management. Initial fracture displacement values that maximized the sensitivity (SN) and specificity (SP) for failure included an AP angulation .11 degrees (SN 75%, SP 64%) and ML translation .12 mm (SN 55%, SP 75%). The failure rate in patients with none, 1, or both of these fracture parameters was 3.1% (1/32), 35.6% (20/56), and 66.6% (12/ 18), respectively.Conclusions: Nearly one-third of patients experienced failure of initial nonoperative management. Failure was found to be associated with greater initial fracture AP angulation and ML translation. Fracture displacement cut-off values were established that may be used by surgeons to counsel patients with these injuries.