Correlation between the subsidence of titanium mesh and CT values of the upper and lower vertebrae of lumbar tumors at different periods after total en bloc spondylectomy

English Keywords:Lumbar neoplasm  Giant cell tumor  CT value  Total en bloc spondylectomy  Prosthesis subsidence

English Abstract:

  【Abstract】 Objectives: To measure the preoperative CT values in hounsfield unit(HU) of the upper and lower vertebrae of lumbar tumor and analyze and determine their relationships with the subsidence of titanium mesh at different follow-up periods after total en bloc spondylectomy(TES). Methods: The data of 29 patients with lumbar tumors who underwent TES with titanium mesh reconstruction in our hospital between January 2008 and May 2018 were retrospectively analyzed, including 12 males and 17 females. The age of the patients was 42.4±14.5 years (23-69 years), and the follow-up period was 121.2 months(48-175 months). The inter-vertebral height of lumbar spine was measured on CT at postoperative 3, 6, 12, and 24 months. According to the difference of intervertebral height between postoperative follow-up and discharge, the patients were divided into subsidence group(>1mm) and non-subsidence group(≤1mm). The number of patients, gender, and age(categorized by median age), tumor location, and postoperative adjuvant radiotherapy of the two groups were collected, and the preoperative CT values(HU) of the upper and lower vertebrae of tumor segments were measured, which were subdivided into low CT value and normal CT value with referrence of the CT value standard of osetoporosis. The differences of clinical parameters between the two groups at different postoperative periods were compared, and ROC analysis was employed to analyze and determine the roles of preoperative CT values of upper and lower vertebral bodies in predicting titanium mesh subsidence. Results: At three months after operation, there were 3 cases in the subsidence group and 26 cases in the non-subsidence group; at 6 months after operation, there were 11 cases in the subsidence group and 18 cases in the non-subsidence group; at 12 months, there were 18 cases in the subsidence group and 11 cases in the non-subsidence group; at 24 months, there were 22 cases in the subsidence group and 7 cases in the non-subsidence group. There was no statistically significant difference in the age, tumor location, and postoperative adjuvant radiotherapy between the two groups at different follow-up time points(P>0.05). At postoperative 6 months, there was statistically significant difference between the two groups in terms of the low CT values of the upper and lower vertebrae(P<0.01). At postoperative 12 months, there was a statistically significant difference in the low CT values of the lower vertebra between the two groups(P<0.01). However, there was no significant difference in the the low CT values of the upper and lower vertebrae between the two groups at 3 and 24 months after operation(P>0.05). The area under the ROC curve was 0.7-0.9, and the accuracy of the preopeative low CT value of upper and lower vertebrae at 6 and 12 months after surgery in predicting titanium mesh subsidence was medium. Conclusions: The preoperative low CT value of the upper and lower vertebrae of the tumor involved vertebral body may be related to the early subsidence rate of the titanium mesh after TES with titanium mesh recontstruction of lumbar tumors.