Virtual Conference
Chih Wei Huang

Chih Wei Huang

Taichung Veterans General Hospital , Taiwan

Title: The residual exposed endplate ratio is predictive of heterotopic ossification after cervical Bryan disc


Heterotopic ossification (HO), a potential complication of cervical disc arthroplasty (CDA), is reportedly a major cause of postoperative artificial disc dysfunction. Residual exposed endplate (REE) is one possible reason for HO development after Bryan CDA. The aim of this study was to determine the cut value of the REE ratio and to predict the development of HO after Bryan CDA based on radiographic analysis.
This retrospective study included consecutive adult patients (>18 years) who underwent 1- or 2-level Bryan CDA by a single neurosurgeon between 2007 and 2016 with two years or more of follow-up were included.
Postoperative radiographic analysis and measurement were performed to obtain the REE(ratio of the residual endplate) ratio and the HO grade. The McAfee classification was used for HO grading. SPSS version 22 was used for statistical analysis of the relationship between the REE ratio and resulting HO formation.
Of 249 patients with 384 surgical levels who underwent Bryan CDA during the study period, 114 (45.8%) received one-level CDA and 135 (54.2%) received two-level CDA. Lateral radiographs showed that 169 implants (44%) had posterior HOs in all grades after two years or more of follow up and 14 implants (3.65%) had severe HO (McAfee grades 3 and 4). In 329 implants (85.7%), a comparison of radiographs to CT examination of HO grading showed a substantial relationship. Using area under the curve (AUC) analysis, a REE ratio >9% (>2.2 mm), with 65.1% sensitivity and 86.5% specificity (60.4% sensitivity and 90.7% specificity), was the cut point for HO formation.
REE is highly correlated with the development of postoperative HO after Bryan CDA, regardless of the level of implantation. An undersized implant causing a REE ratio >9% is a predictor of postoperative HO formation after cervical Bryan CDA.