Reverse-engineered stock plates as a "makeshift" patient-specific alternative: expanding the role of conventional plates in mandibular free fibula reconstruction.

[AIM] Stock reconstruction plates in mandibular reconstruction lack the ability to use pre-determined screw holes in the digital workflow, reducing their accuracy compared to patient-specific implants (PSIs). We aim, through reverse engineering and integration of predictive screw holes, to enhance virtual surgical planning (VSP) guided reconstruction, making it a useful option in resource-limited settings.

[METHODS] Ten patients underwent mandibular reconstruction using free fibula flaps. The stock plates were pre-bent on STL models, 3D scanned and through reverse engineering; the screw hole positions were transferred to mandibular and fibular guides. Accuracy was evaluated by comparing planned and actual mandibular positions across four anatomical landmarks, using both linear and angular deviation measurements. Further, demographics and clinical variables were tested to assess their impact on reconstruction accuracy.

[RESULTS] The mean overall linear deviation was 1.92 mm, and RMSE was 2.11 mm, with no significant deviations. Compared to a clinical threshold of 2 mm, all deviations were within range, except the anteroposterior deviation, which was significantly lower (1.36 mm. The mean gonial angle deviation was 1.66°. No clinical or demographic variables significantly influenced accuracy, except for higher intergonial deviation in two-segment reconstructions, specifically in lateral defects.

[CONCLUSION] The reverse-engineered stock plates demonstrated accuracy comparable to the 2 mm clinical threshold. This method offers a promising, cost-effective alternative to PSI for mandibular reconstruction, especially in resource-limited settings, without compromising clinical outcomes. Further research is warranted to improve the workflow of the "makeshift" custom plates.

[TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION] NCT05672056, Registered 2023-01-03.