Levy E, Rumley J
Center for Spine and Orthopedics, Denver, CO, United states
Introduction
Anterior cervical discectomy and fusion (ACDF) is a well-established and effective treatment for symptomatic cervical myelopathy and radiculopathy. Interbody cage subsidence is a known complication associated with ACDF. Subsidence rates of ACDF interbody cages with single long anterior plate fixation has been variable in the published literature with ranges from 0-80%. Recent systematic reviews of published literature report a mean incidence of 21%.1 The rate of subsidence for ACDF with multilevel segmental plate fixation has not been studied.
Methods
The electronic medical record (EMR) at Center for Spine and Orthopedics will be queried to identify patients who underwent two and three level ACDF with segmental anterior plate fixation using the appropriate billing codes. These patients will have the operative reports reviewed to ensure appropriate inclusion in the study. Initial post-op and 6 month and 1 year postoperative cervical spine x-rays will be evaluated to calculate subsidence of the interbody cage at both time points. All patients from a single surgeon from Jan 1, 2020 until Jan 1, 2022 will be included if they meet inclusion criteria.
Statistical analysis will be performed using SAS v9.4. Descriptive Statistics will be computed for all study variables. Continuous variables will be described with measures of central tendency (mean, median) and dispersion (range, standard deviation). Categorical variables will be summarized as frequencies and percentages. Categorical variables will be compared with the Chi-Square test, and continuous variables will be compared with the Student’s t-test or nonparametric equivalent, Mann Whitney U test. We will utilize all of the relevant patient data and radiographic data that meet inclusion criteria in order to give us the strongest sample size in order to draw conclusions from. P-values less than 0.05 will be considered statistically significant.
Results
Initial post-op, 6 month and 1 year postoperative cervical spine x-rays were evaluated to calculate subsidence of the interbody cage at both time points. Subsidence was defined as ≥ 3mm loss of intervertebral height compared to immediate postoperative x-rays. Our results were compared to established and previously published subsidence rates for multilevel ACDF with single long anterior plate fixation. 206 patients met inclusion criteria. All patients studied were from a single surgeon from Jan 1, 2020 until Jan 1, 2022. The segmental plate fixation showed no statistically significant increase in subsidence compared to standard multilevel long anterior ACDF plate fixation. Our overall subsidence rate was 3.1% which is below many of the published values for ACDF interbody cage subsidence rates.
Conclusions
There is no increased risk of subsidence in patients undergoing multilevel ACDF treated with segmental plate fixation compared to established and previously reported subsidence rates with multilevel ACDF with single long anterior plate fixation.
