Comparison of percutaneous dorsal versus volar fixation of scaphoid waist fractures using a computer model in cadavers.

PURPOSE Percutaneous screw fixation (PSF) is widely used to treat acute nondisplaced scaphoid waist fractures. PSF can be performed through a volar or dorsal approach. The aim of our study was to compare a dorsal versus volar surgical approach for PSF according to the sagittal orientation of the waist fracture (B1 or B2 in Herbert and Fisher's classification scheme, in which B1 and B2 designate, respectively, oblique and transverse nondisplaced scaphoid waist fractures) on computer modeling of cadaver wrists. METHODS We used 12 upper limbs, and for each wrist we performed 3 computed tomography scans in maximal flexion, neutral position, and maximal extension. For each position, a parasagittal slice corresponding to the plane of ideal screw placement was obtained by numerical reconstruction. On each slice, we modeled B1- and B2-type fractures and the placement of the corresponding screws (S1 and S2) inserted through a volar or dorsal approach. Optimal screw orientation was perpendicular to the fracture. For each configuration, we measured the angle between the S1 screw and B1 fracture, which we designated V1 when modeling volar PSF and D1 when modeling dorsal PSF. Similarly, we measured angles V2 and D2. RESULTS For B2 fractures, virtual screw placement perpendicular to the fracture was achieved equally well with the 2 approaches. For B1 fractures, the virtual screw could not be placed perpendicular to the fracture with either approach, but the dorsal approach with maximal wrist flexion allowed the best screw placement. CONCLUSIONS For B2 fractures, the dorsal and volar approaches allow optimal virtual screw placement, and the choice of the approach depends on the surgeon's preference. For B1 fractures, we recommend the dorsal approach.