Lower Hounsfield units on CT are related to 3D-Print Artificial Vertebral Body subsidence after anterior cervical corpectomy and fusion

Abstract Objective The subsidence of vertebral body replacement may occur after cervical spine ACCF surgery, which may lead to cervical kyphosis, spinal cord compression and neurological dysfunction. The author used CT to measure the relationship between HU value and the subsidence of 3D-Print artificial vertebral body(3D-PAVB) after cervical spine ACCF surgery. Methods The data of patients with cervical spondylosis treated by ACCF surgery from 2017 to 2020 in Bethune Hospital of Shanxi were analyzed retrospectively. The statistical data included age, sex, type of cervical spondylosis, body mass index (BMI), disease type, surgical segment, whether to incorporate the ACDF,vertebral height, Cobb Angle, and HU values of vertebral body and endplate. Clinical efficacy was evaluated using VAS, JOA and NDI. Univariate analysis was performed to determine the factors contributing to the subsidence of the 3D-printed artificial vertebra, and independent risk factors were determined by logistic regression. The ROC curve and area under the curve (AUC) were used to analyze the HU value and predict the 3D-PAVB subsidence. Results 66 patients met the inclusion criteria. 19 patients had 3D-PAVB subsidence, the subsidence rate was 28.8%. Postoperative JOA, VAS and NDI scores of patients in the subsidence group and non-subsidence group were significantly improved. Univariate analysis showed statistically significant differences in age, diabetes, smoking and lower vertebral CT values between the two groups. The average HU value of the subsidence group (251.39 ± 52.62, n = 19) was significantly lower than that of the non-subsidence group (317.06 ± 73.59, n = 47, p<0.01). Multivariate analysis confirmed that smoking and HU of the lower vertebra were independent risk factors for 3D-PAVB subsidence, with an AUC of 0.772 and an optimal threshold of 272 for HU (sensitivity 78.9%, specificity 74.5%). Conclusion Smoking and low HU before surgery are independent risk factors for early postoperative 3D-PAVB subsidence. Understanding smoking history before surgery and measuring CT HU value are helpful to predict early 3D-Print artificial vertebral subsidence after cervical spine ACCF surgery. The lower the CT HU value, the higher the subsidence risk.