Improving subtalar arthrodesis with a skin-matched patient-specific surgical guide: A comparative cadaveric study

To evaluate the accuracy and fluoroscopy shot count of a novel skin-matched, patient specific Instrument (PSI) for subtalar arthrodesis compared with the conventional freehand technique in a cadaveric setting.

Twelve cadaveric specimens were randomized into PSI-guided (n = 6) and freehand (n = 6) groups, with preoperative computed tomography scans used to design 3D-printed guides. Each PSI incorporated 2 pre-angled cannulated sleeves to allow optimal guidewire placement from the calcaneus into the talus. Outcomes included fluoroscopy usage, number of wire placement attempts, angular devia tion between planned and actual wire trajectories (assessed in sagittal, coronal, and axial planes), and linear deviations at entry (calcaneal) and distal (talar) points. Statistical analysis used the Mann-Whitney U and Wilcoxon signed-rank tests with significance set at P < .05.

Fluoroscopy usage was significantly lower in the PSI group (median 3.0 [interquartile range, IQR 3.0-6.0]) compared with the free hand group (17.0 [15.3-18.8]; P = .009). Similarly, the number of attempts was reduced in the PSI group (2.0 [2.0-2.8]) versus the freehand group (6.0 [5.3-6.8]; P = .009). Angular deviation from the preoperative plan was low (median 3.0° [IQR 1.8°-4.7°]), indicating high trajec tory fidelity. Linear deviation at the calcaneal entry point was minimal (median 0.9 mm [IQR 0.4-1.2 mm]), whereas greater variability occurred distally at the talar point (median 3.6 mm [IQR 2.0-5.1 mm]), remaining within clinically acceptable limits.

The use of a skin-matched PSI for subtalar arthrodesis significantly reduced the number of fluoroscopy shots and wire place ment attempts while ensuring high accuracy of guidewire trajectory. These findings support the potential of 3D-printed PSIs to improve surgical precision, suggesting clinical applicability for subtalar arthrodesis and related hindfoot interventions.   Cite this article as: Karaismailoglu B, Subasi O, Tung W, et al. Improving subtalar arthrodesis with a skin-matched patient-specific surgical guide: a comparative cadaveric study. Acta Orthop Traumatol Turc., 2025;59(6):368-373.