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.