American Association for Hand Surgery
Theme: Beyond Innovation

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Evaluating Factors Associated with Scaphoid Nonunion Following ORIF
Pooja Prabhakar, BS1; Lauren Wessel, MD2; Joseph Nguyen, MPH2; Michelle Carlson, MD2; Duretti T Fufa, MD2
1UT Southwestern, Dallas, TX, 2Hospital for Special Surgery, New York, NY

INTRODUCTION:
Scaphoid fractures are a common wrist injury and can represent clinical challenges when complicated by nonunion or avascular necrosis. Nonunion after open reduction and internal fixation (ORIF) of scaphoid fractures is reported in 5-30% of cases. The purpose of this study is to determine fracture characteristics and surgical factors which may influence progression to nonunion after scaphoid fracture ORIF.
METHODS:
This was a retrospective case control study of scaphoid nonunions treated at a single institution between 2003 and 2017. Criteria for inclusion required surgical fixation within six months from date of injury, one year postoperative follow-up, and post-operative CT demonstrating union or nonunion. Sixteen nonunions meeting criteria were identified. Nonunions were matched by age, sex and fracture location to patients who progressed to union in a 1:2 ratio. Three-dimensional modeling of each fracture was performed to assess the volume of fracture fragments, fracture orientation, screw orientation, distance from screw to subchondral bone, and area of fracture across respective zones of the scaphoid. These characteristics as well as mechanism of trauma, length of time to initial treatment, implant length and caliber, surgical approach and use of bone graft were modeled in a conditional stepwise regression analysis.

RESULTS:
Sixteen nonunion cases were matched with 32 unions in this series of 48 scaphoid fractures treated by ORIF. Fracture location was proximal pole in 19% (9/48) and waist in 81% (39/48). Length of time from injury to initial ORIF was significantly higher in the nonunion group (63.3 vs. 29.5 days). On multivariate analysis, longer time to surgical fixation and smaller average percent of proximal fragment volume were significantly associated with scaphoid nonunion after ORIF. Increased likelihood for nonunion was found when the fracture was treated greater than 31 days from injury and when fracture volume was less than 34% of the entire scaphoid.

DISCUSSION AND CONCLUSION:
These results suggest that scaphoid fractures should be treated within one month from injury in order to decrease nonunion risk. Additionally, patients with fracture fragments that are less than 1/3 of the entire scaphoid volume should be counseled with regard to increased nonunion risk.







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