Predictive value of vertebral Hounsfiled Unit for titanium mesh cage subsidence following ACCF surgery.

OBJECTIVE:To investigate the predictive value of cervical Hounsfiled Unit (HU) values for postoperative titanium mesh cage (TMC) subsidence. METHODS:Clinical data of patients who underwent ACCF surgery for degenerative cervical myelopathy between January 2016 and August 2018 were analyzed. Among the 126 patients included, 74 were male and 52 were female, with a mean age of 61.0 ± 9.9 years. The mean follow-up was 37.1 ± 11.2 months. Preoperative vertebral HU values were measured and the degree of TMC subsidence during follow-up was assessed. Patients were divided into two groups according to the presence or absence of subsidence: the subsidence group and the control group. Vertebral HU values were compared between the two groups, and correlation analysis was performed between HU values and TMC subsidence values. In addition, the predictive value and threshold of HU were analyzed by using ROC. RESULTS:There were 22 patients (14 males and 8 females) who developed TMC subsidence (subsidence group), while 104 patients (60 males and 44 females) did not develop TMC subsidence (control group) during follow-up. Comparative analysis of demographic characteristics between the two groups showed no significant differences in gender, age, BMI, diagnosis, surgical levels, and follow-up duration (all P values > 0.05). There was a significant difference in mean HU between the subsidence group (287.6 ± 49.6) and the control group (342.4 ± 61.4) (t = -3.92, P < 0.01). In the subsidence group, there was a significant correlation between subsidence values and HU values (r = -0.52, P = 0.01), whereas no such correlation was observed in the control group (r = - 0.07, P = 0.51). ROC analysis indicated that vertebral HU values could potentially be used to predict subsidence after ACCF, with an area under the ROC curve of 0.77 (95% CI 0.66-0.87; P < 0.01). The optimal HU threshold was found to be 298, with a sensitivity of 76.9% and specificity of 68.2%. CONCLUSION:Preoperative vertebral HU values were associated with postoperative TMC subsidence. Vertebral HU may be a valuable predictor of postoperative subsidence.