Computer-assisted navigation for dorsal percutaneous scaphoid screw placement: a cadaveric study.

Purpose: To investigate computer-assisted surgery (CAS) for dorsal insertion of percutaneous scaphoid screws and to compare operative time, accuracy, and fluoroscopy time with the traditional mini C-arm method. We hypothesized that CAS techniques would improve accuracy, reduce actual K-wire insertion time, and decrease fluoroscopy time.

Methods: Ten fresh cadaveric upper limbs were randomized to either CAS or traditional dorsal percutaneous scaphoid screw placement by a single surgeon. Custom orthoses were applied to the CAS arms followed by intraoperative computed tomography (CT) scan and navigation calibration. Time was recorded for the portion of setup that required surgeon input, ideal guide wire placement, and fluoroscopy. Postoperative CT scans of the CAS arms were obtained to confirm accuracy. Two-tailed unpaired Student t test was used to analyze the outcome variables.

Results: The CAS group required on average 4.8 ± 0.8 minutes longer for setup. The time for placement of the guidewire in the ideal position was 4.6 ± 1.5 minutes in the CAS group compared with 11.8 ± 4.4 minutes in the control group. Fluoroscopy time was 18 ± 4 seconds for the CAS group and 114 ± 38 seconds for the control group. Postoperative CT scans demonstrated 1.5 ± 0.6 mm maximum deviation from the planned ideal screw. No significant differences were found in the accuracy between methods, the number of guidewire attempts, or the total surgical time.

Conclusions: Computer-assisted surgery navigation of dorsal percutaneous scaphoid screw placement takes on average 5 minutes longer to set up, but leads to significantly reduced guidewire placement time and no differences in overall procedural time. This CAS method was as accurate as the traditional method and resulted in an approximate 6-fold reduction in fluoroscopy time.

Clinical Relevance: This is an effective imaging alternative to the mini C-arm for scaphoid fixation using existing intraoperative CT scanners and navigation software.