Patient-specific Implants Improve Volumetric Surgical Accuracy Compared to Stock Reconstruction Plates in Modern Paradigm Virtual Surgical Planning of Fibular Free Flaps for Head and Neck Reconstruction

Background

Virtual surgical planning (VSP) for composite microvascular free flaps has become standard of care for oncologic head and neck reconstruction. Controversy remains as to the use of three-dimensional (3D)-printed patient-specific titanium implants (PSIs) versus hand-bent stock reconstruction plates. Proponents of PSIs cite improved surgical accuracy, reduced operative times, and improved clinical outcomes. Detractors purport increased cost associated with PSIs and presumed equivalent accuracy with less expensive stock plates.

Purpose

The study purpose was to measure and compare the 3D-volumetric accuracy of PSI versus stock reconstruction plates among subjects undergoing VSP-guided mandibular fibular free flap reconstruction.

Study Design, Setting, Sample

A retrospective cohort study of subjects undergoing VSP-guided fibular free flap reconstructions at Mayo Clinic between 2016 and 2023 was performed. Subjects were excluded for non-VSP guidance, midfacial reconstruction, nonfibular free flaps, and lack of requisite study variables.

Predictor Variable

The primary predictor was the type of reconstruction plate utilized (PSI vs stock plate).

Main Outcome Variable

The main outcome was volumetric surgical accuracy of the final reconstruction compared to the preoperative surgical plan by root mean square error (RMSE) calculation. Lower RMSE values indicated a higher surgical accuracy.

Covariates

Covariates included age, sex, race, smoking status, American Society of Anesthesiologists (ASA) Physical Status Classification System, Charlson Comorbidity Index, preoperative diagnosis, and number of fibular segments.

Analyses

Differences in surgical accuracy were assessed between preoperative and postoperative segmented scans using volumetric overlays from which RMSE values were calculated. Univariate and multivariate modeling of plate type to RMSE calculation was performed. Statistical significance set to P < .05.

Results

Total of 130 subjects were identified, 105 PSI and 25 stock plates. Calculated mean RMSE in millimeters (mm) for stock plates was 1.46 (standard deviation: 0.33) and 1.15 (standard deviation: 0.36) for PSIs. Univariate modeling demonstrated a statistically significant difference in RMSE of 0.31 (95% confidence interval: 0.16-0.47) (P < .001) equating to a 21.2% (P < .001) improved volumetric surgical accuracy for PSIs. The association of improved volumetric accuracy with PSIs has been maintained in all multivariate models controlling for confounding.

Conclusion and Relevance

In modern era VSP-guided head and neck fibular free flap reconstruction, patient-specific 3D-printed titanium implants confer a statistically significant improvement in volumetric surgical accuracy over stock reconstruction plates.