Lateral Deviation of the Hyoid Bone and Thyroid Cartilage Influences Prevertebral Soft-Tissue Swelling and Dysphagia After Anterior Cervical Diskectomy and Fusion

BACKGROUND AND OBJECTIVES: Prevertebral soft-tissue swelling (PSTS) after anterior cervical diskectomy and fusion (ACDF) is known to be influenced by several factors. We considered the effect of lateral deviation on the traction force and attempted to find a relationship with the PSTS. This study was designed to evaluate the preoperative lateral deviation of the hyoid bone and thyroid cartilage and its effect on PSTS, airway collapse, and clinical outcomes after ACDF. METHODS: Preoperative lateral deviations of the hyoid bone and thyroid cartilage at the superior cornu and inferior cornu were measured. To assess the effect of lateral deviation, patients who underwent 1 or 2 level ACDF with the left-sided approach were divided into a deviation group (left-sided deviation >5 mm or >10 mm) and a nondeviation group (left-sided deviation <5 mm or <10 mm). Difference of preoperative and postoperative PSTS (dPSTS), airway collapse, dysphagia score, and Neck Disability Index were compared between the 2 groups. RESULTS: Lateral deviation was measured in 290 patients, and 145 were enrolled to assess the effect of lateral deviation. Left-sided deviation was more common than right-sided deviation in all 3 structures (the hyoid bone, superior cornu, and inferior cornu of the thyroid cartilage). The deviation group demonstrated a significantly larger dPSTS at the C3 and C4 levels, more airway collapse at the C4 level, and a higher dysphagia score. There was no significant difference in the Neck Disability Index between the 2 groups. Lateral deviation significantly correlated with dPSTS (C3, C4, C5, and C6 levels) and airway collapse (C3 and C4 levels). CONCLUSION: A left-sided deviation of more than 5 mm of the hyoid bone or thyroid cartilage discouraged the left-sided approach for ACDF because of the aggravation of dPSTS, airway collapse, and dysphagia postoperatively.