Can anterior midfoot tarsectomy procedure be improved using patient-specific cutting guide? An experimental study.

Background: Anterior midfoot tarsectomy remains difficult to achieve for the treatment of cavovarus foot. Computer-assisted planning and printed patient-specific cutting guides (PSCG) aim to reduce technical errors. This study investigated the accuracy and safety of PSCG-assisted anterior tarsectomy from a cadaveric analysis.

Hypothesis: PSCGs provide an accurate correction and safety, disregarding the experience of the operator.

Material and methods: Ten foot and ankle specimen underwent an anterior tarsectomy using PSCG with a dorsal closed-wedge effect of 15°. An initial CT-scan of the foot was performed to create 3D geometrical foot models, then used to virtually plan the closed osteotomy. Outcomes were investigated from preoperative, computer-assisted planed and postoperative 3D reconstructions. Accuracy was defined as differences between planed and postoperative reconstructions, using computational matrix transformation to quantify angular corrections and surface-distance mapping. Differences in accuracy between two differently-skilled operators were evaluated. Finally, the specimens were dissected to verify the absence of iatrogenic lesions.

Results: The mean sagittal error was 1.1° ± 1.0° (95% CI: 0.4-1.7°), and the accuracy in the Méary's angle correction was 2.5° ± 1.7° (95% CI: 1.4-3.6°). The maximal error was shown for the setting of pronation-supination. Overall, 92% of the surface distance mapping were < 2 mm. No significant differences in accuracy were found between operators. No iatrogenic neuro-vascular lesions were found after dissection.

Conclusions: Our study validated the use of PSCG in performing anterior tarsectomy with a good accuracy, with neuro-vascular safety. Therefore, the use of PSCG can decrease the risk for iatrogenic flatfoot or undercorrection. The operator experience did not influence the risk for angular errors, as shown by other papers dealing with PSCG. Patient-specific cutting guides-assisted anterior tarsectomy showed high accuracy to correct Meary's angle, disregarding the experience of the operator. Further perspectives need to be considered, including correction guides to monitor the pronation-supination.

Level of evidence: IV; experimental study.