Abstract
Purpose: We compare the accuracy and precision of patient-specific plastic guides versus computer-assisted navigation for distal radius osteotomy (DRO). We hypothesize that guides would provide similar accuracy and precision compared to computer-assisted surgery, and that they would be faster to use than navigated surgery.
Method: We used CT scans, computer models, and planned corrections of radii from seven patients who had previously received computer-assisted DRO. The planned correction included the locations and directions of the screw holes for the fixation plate on the intact deformed radius. Using computer-assisted technique, the surgeon drills the holes for the fixation plate using computer navigation before performing the osteotomy; after cutting the radius, the plate is fixated to the distal radius, and the distal radius is distracted until the holes in the proximal radius align with the holes of the fixation plate. A patient-specific guide can be manufactured that fits on the intact deformed radius to guide the drilling of the screw holes. The guide is designed so that it mates exactly with the dorsal surface of the radius. Each guide was designed using custom software and manufactured in ABS plastic using a 3D printer. The surgeon places the guide on the radius and uses a metal drill sleeve in each guide hole to guide the drilling of the plate screw holes. We manufactured urethane plastic phantoms of the seven deformed radii. Our laboratory experiment had six surgeons each perform four computer-assisted and four patient-specific guide procedures on the phantom radii; the specimen and type of guidance were randomly chosen. The time from the start of the procedure to when the shaping of the distal radius was completed was recorded; we did not record the time required to cut and fixate the radius because this time does not depend on the type of guidance used. The plated phantoms were assessed for errors in ulnar variance, radial inclination, and volar tilt as compared to the planned correction.
Results: The results for the computer-assisted procedures were: ulnar variance error (−0.2 +/ − 2.0 mm), radial inclination error (−0.9 +/ − 6.1 deg), volar tilt error (−0.9 +/ − 1.9 deg). The results for the customized jig procedures were: ulnar variance error (−0.7 +/ − 0.6 mm), radial inclination error (−1.0 +/ − 1.4 deg), volar tilt error (−0.4 +/ − 2.2 deg). There were no significant differences detected in the means of the measurements (significance level 0.05) using the two-sample t-test. Significant differences were detected in the variances of the ulnar variance and radial inclination errors (significance level 0.05) using Levene’s test. It took (705 +/ − 144 sec) to perform the computer-assisted procedures and (214 +/ − 98 sec) to perform the customized guide procedures. The differences between the means and variances were statistically significant.
Conclusion: Patient-specific guides are as accurate, more precise, and require less time than computer-assisted navigation for DRO.
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