A comparative study of the predictive efficacies of preoperative cervical vertebral bone quality score and endplate bone quality score on cage subsidence risk after anterior cervical discectomy and fusion surgery

English Keywords:Anterior cervical discectomy and fusion  Cervical endplate bone quality score  Cervical vertebral bone quality score  Zero-Profile  Cage subsidence

English Abstract:

  【Abstract】 Objectives: To evaluate the clinical values of cervical vertebral bone quality(CVBQ) score and cervical endplate bone quality(CEBQ) score in predicting the settlement of Zero Profile(Zero-P) cage after anterior cervical discectomy and fusion(ACDF). Methods: A retrospective analysis was performed on 72 patients who underwent ACDF with Zero-P cage in the Second Affiliated Hospital of Soochow University. General patient information(including sex, age, comorbidity), laboratory parameters(such as blood calcium and blood glucose), surgical details(surgical level and cage type), and imaging data(preoperative cervical MRI and anteroposterior and lateral X-rays within one week and after more than three months) were collected. On the lateral X-rays taken within one week and >3 months postoperatively, the heights of the upper and lower margins of vertebrae were measured, and the difference between was defined as the cage subsidence distance. Patients with a subsidence distance≥2mm were assigned to the subsidence group, and those with <2mm subsidence distance were divided to the non-subsidence group. On preoperative cervical sagittal T1-weighted MRI, placing regions of interest(ROIs) in the medullary region of adjacent vertebral bodies, the subchondral bone region of the endplates, and the cerebrospinal fluid(CSF) in the cerebellomedullary cistern. CVBQ and CEBQ values were the ratios of the average signal intensity of the medullary region of the surgical adjacent vertebral bodies(for CVBQ) and the subchondral bone region of the endplates(for CEBQ) to the signal intensity of the cerebrospinal fluid in the cerebellomedullary cistern. A stratified analysis by gender was conducted to further clarify whether the predictive value of bone quality scores for subsidence is influenced by gender factors. The Pearson correlation coefficient was used to assess the relationship of CVBQ and CEBQ with cage subsidence distance. Receiver operating characteristic(ROC) curves were applied to evaluate the diagnostic efficacy of CVBQ and CEBQ for cage subsidence. Univariate logistic regression analysis was performed to screen for potential risk factors, after that age and diabetes, which showed statistical significance, along with CVBQ and CEBQ, were incorporated into the multivariate analysis to assess their independent effects. Results: Cage subsidence occurred in 14 patients(subsidence rate: 19.4%). Compared with the non-subsidence group, the subsidence group of patients was older(male: 61.4±16.5 years vs 51.1±10.8 years, P=0.049; female: 62.6±13.1 years vs 51.2±7.8 years, P=0.005) and had a higher proportion of patients with diabetes(male: 42.9% vs 3.4%, P=0.018; female: 42.9% vs 6.9%, P=0.040). Both CVBQ and CEBQ were significantly higher in the subsidence group(CVBQ-male: 2.75±0.73 vs 2.02±0.53, P=0.004; female: 2.84±0.69 vs 2.00±0.40, P=0.005; CEBQ-male: 2.82±0.688 vs 2.05±0.56, P=0.004; female: 2.94±0.68 vs 2.05±0.42, P=0.002). Pearson correlation analysis revealed a moderate positive correlation between both CVBQ(r=0.58, P<0.001) and CEBQ(r=0.59, P<0.001) with subsidence distance. ROC curve analysis indicated that both CVBQ(AUC=0.83) and CEBQ(AUC=0.85) had good predictive values for subsidence, with CEBQ showing slightly better predictive performance. Univariate logistic regression analysis identified age, diabetes, CEBQ, and CVBQ as risk factors for subsidence(P<0.05). Multivariate analysis showed that after adjusting for age and diabetes, both CEBQ(OR=11.466, P=0.004) and CVBQ(OR=8.804, P=0.005) remained independent risk factors for subsidence, while age and diabetes lost independent significance. The strength of association with subsidence was greater in CEBQ than in CVBQ. Conclusions: Patients with higher CVBQ and CEBQ scores are more likely to experience fusion cage subsidence, and both CEBQ and CVBQ can be used to predict cage subsidence in patients after single-level ACDF, CEBQ has better predictive ability than CVBQ.