Lee, C.; Flores, A. R.; Culcu, M.; Ropper, A. E.; Avila, R.

Dysphagia, difficulty swallowing due to irritation or damage to the esophagus, is one of the most common complications following anterior cervical discectomy and fusion (ACDF), the most frequently performed cervical spine procedure in the United States. Surgical retraction hardware imposes sustained compression on the esophagus during surgery, generating nonuniform stress and strain fields that may contribute to temporary postoperative soft tissue damage. Current intraoperative assessment relies on visual inspection and manual inspection by the surgical team and does not provide quantitative measures of esophageal deformation, strain, or retraction displacement. Here, we present a comprehensive mechanics analysis of esophageal compression during ACDF that integrates experiments on esophageal phantoms, nonlinear finite element modeling, and theoretical thick-wall scaling relationships. Modeling results quantify peak contact pressures and corresponding stress distributions, identifying conditions under which circumferential strain in the compressed esophageal wall increases sharply as localized pressures approach the upper physiological range (~6-17 kPa). Parametric investigation of retractor blade width, placement depth, and polymeric biocompatible coating properties demonstrates that targeted, yet mechanically simple, design modifications can help to attenuate strain concentrations. In particular, the introduction of compliant polymeric coatings redistributes contact loads and reduces peak wall stress by up to 20% relative to unbuffered blades (17 kPa to 13.5 kPa). Increasing blade width from 20 mm to 50 mm further decreases peak interface stress from 2.48 kPa to 0.45 kPa, corresponding to an 82% reduction. Reducing these stresses may help limit mechanically induced complications such as postoperative dysphagia. Experiments performed on esophageal phantoms with embedded pressure sensors replicate surgical ACDF retraction protocols under displacement-controlled conditions. This setup establishes physiologically relevant loading and enables quantitative validation of computational predictions by correlating measured voltage output with contact pressure and esophageal deformation. Measured relationships between applied retraction displacement, contact pressure, and tissue deformation govern stress amplification during ACDF retraction. Together, these results establish a predictive mechanics framework that links retractor blade design variables to esophageal stress fields, providing quantitative criteria to mitigate soft tissue damage during ACDF.