P18. Factors influencing the lowest visible level on lateral cervical fluoroscopy during anterior cervical discectomy and fusion

Abstract

BACKGROUND CONTEXT

Obtaining adequate intraoperative visualization of cervical vertebra can prove challenging during anterior cervical discectomy and fusion (ACDF). There is little information about patient and surgeon factors that can effectively predict the degree of intraoperative visualization of cervical vertebral level. We hypothesize that the degree of cervical visualization is impacted by specific patient variables, preoperative lateral upright radiographic parameters, and intraoperative patient positioning technique.

PURPOSE

The purpose of this study is to identify patient variables and surgeon positioning variables that influence lowest visible vertebra on intraoperative radiographs for patients undergoing ACDF.

STUDY DESIGN/SETTING

Retrospective chart review at a regional multicenter hospital.

PATIENT SAMPLE

Adult patients who underwent ACDF

OUTCOME MEASURES

Identification of predictive demographic factors for intraoperative visualization, as well as a novel cervical visualization score calculated based on intraoperative vertebral level difference from preoperative baseline upright cervical radiographs.

METHODS

This retrospective study examined adult patients who underwent ACDF in a large, integrated system. Patient demographic factors were obtained to identify predictors of intraoperative visualization based on a series of radiographic cervical parameters measured on upright radiographs. A novel cervical visualization score was calculated based on intraoperative vertebral level difference from preoperative baseline level. Patient demographic and radiographic parameters were analyzed using a multivariate backward linear regression. Differences in pre-and-intraoperative visualization among traction versus non-traction techniques were determined with a two-sample t-test. One-way ANOVA and post hoc analyses were used to identify differences in visualization scores in traction and non-traction groups separately. Inter-rater reliability was assessed for all radiographic measurements made by two independent researchers.

RESULTS

There were 151 electronically identified patients included. Elevated BMI and use of traction significantly reduced visualization scores. High T1 slope modestly improved visualization. Traction group visualization scores at lowest visualized vertebra (C7 lower half and C7-T1 disc) showed a significant decrease compared to non-traction group with equal preoperative visualization. Pairwise comparisons for traction stabilized patients showed a significantly reduced visualization at the preoperative C7-T1 disc level compared to C6 upper half. ANOVA analysis within the non-traction group showed no statistical significance. The averaged ICC of 0.90 demonstrates excellent inter-rate reliability (ICC range of 0.75-0.97)

CONCLUSIONS

These data indicate that specific factors such as BMI, use of traction and T1 slope impact the lowest visible cervical vertebra for patients undergoing ACDF. Patients without use of traction have similar visualization scores across all preoperative vertebral levels. In addition, use of intraoperative traction appears to reduce visualization scores especially at the C7-T1 level.

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.