Initial Patella Vertical Fracture Displacement Is a Predictor of Nonunion and Hardware Failure

OBJECTIVES: To determine if initial vertical fracture displacement affects postoperative outcomes after operative treatment of patella fractures. DESIGN: Prognostic retrospective study. SETTING: Single multisite urban academic institution. PATIENT SELECTION CRITERIA: Included were patients aged ≥18 years who underwent open reduction internal fixation of a patella fracture (AO/OTA 34A-C) with minimum 6-month follow-up and complete trauma knee x-ray series. Vertical fractures and those without significant vertical displacement (26.6 mm and >21.7 mm identified patients at increased risk for nonunion and hardware failure. Each millimeter increase in displacement raised nonunion and hardware failure risk by 14.9% (OR = 1.1, P = 0.003) and 14.6% (OR = 1.1, P = 0.003). CONCLUSIONS: This study supports the future use of initial vertical fracture displacement as a prognostic tool for nonunion and hardware failure after patella open reduction internal fixation. Displacement >2 cm placed patients at high risk for these complications. Nonunion rates were higher in both suture-only and screw-with-suture fixation when compared with other fixation constructs. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.