Radiographic Parameters to Predict Union After Volar Percutaneous Fixation of Herbert Type B1 and B2 Scaphoid Fractures

Purpose To study the angle of screw placement in relation to the scaphoid fracture plane and its effect on union after percutaneous fixation of scaphoid waist fractures. Methods Twenty-four consecutive scaphoid waist fractures were retrospectively evaluated for the orientation of screws in relation to the fracture plane using a method in which the sum-of-smaller angles (SSA) in 3 different radiographs were used to correlate with time to fracture union. Results All but one patient achieved union after percutaneous fixation of the scaphoid. Another patient required revision surgery within the study period for inadequate fixation. A shortened time to union was significantly correlated to larger SSA. Conclusions SSA may be a reasonable predictor of union after percutaneous fixation of scaphoid waist fracture. It can be reliably calculated using plain radiographs. An SSA of 190° or more correlated with union by 8 weeks postoperatively. Type of study/level of evidence Prognostic IV.