Abstract: BACKGROUND: The ideal distribution in percutaneous vertebroplasty is to make the bone cement diffuse and evenly distributed in the vertebral body as much as possible, to avoid local agglomeration and cause uneven stress distribution in the injured vertebra and fracture again. The difficulty of clinical practice is determining how to distribute bone cement to achieve the most ideal state.
OBJECTIVE: To investigate the clinical significance and distribution characteristics of CT values in the compression fracture vertebra and L1 in patients with osteoporotic vertebral compression fractures. 
METHODS: From February 2021 to February 2022, 47 patients with osteoporotic vertebral compression fractures were selected at Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, 22 males and 25 females, aged (71.3±8.8) years. All patients received percutaneous vertebroplasty. CT values of different regions in injured vertebra and L1 vertebra were measured before operation. Patients were divided into high CT value injection group (n=24) and low CT value injection group (n=23) according to the relative high or low CT value of the area where the puncture needle tip was located during the operation. After percutaneous vertebroplasty, the distribution of bone cement, Cobb angle of kyphosis, anterior edge and middle height of injured vertebral body were measured. 
RESULTS AND CONCLUSION: (1) Eight of the 47 patients affected L1 osteoporotic vertebral compression fractures. The CT value of the L1 vertebral body region in the middle 1/3 area was significantly higher than that of the upper and lower 1/3 areas in 47 patients (P < 0.05). The CT value of the anterior half of the vertebral body was lower than that of the posterior half (P < 0.05). The CT value of the upper 1/3 areas of the compression fractures vertebra was significantly higher than that of the middle and lower 1/3 areas (P < 0.05), and the CT value of the anterior half of the vertebral body was lower than that of the posterior half (P < 0.05). (2) Cobb angle of kyphosis, anterior edge and middle height of injured vertebral body in high CT value injection group and low CT value injection group after operation were significantly improved compared with those before operation (P < 0.05); there was no significant difference between the two groups (P > 0.05). (3) The distribution of bone cement in 24 cases of high CT value injection group was diffuse type, while in 23 cases of low CT value injection group, the distribution of bone cement was diffuse type in 2 cases and non-diffuse type in 21 cases. There was a difference in the distribution of bone cement between the two groups (P < 0.05). The point biserial correlation analysis showed that there was a significant positive correlation between the type of bone cement dispersion and the relative CT value of the injection area (r=0.918, P < 0.05). (4) These findings confirm that CT values in the L1 vertebra and the injured vertebra have a specific regional distribution pattern in patients with osteoporotic vertebral compression fractures. There is a correlation between the CT value in the region where the needle tip is located and the type of bone cement distribution in percutaneous vertebroplasty. The tip of the puncture needle is placed in an area with a high CT value, which promotes the uniform diffusion of bone cement throughout the vertebral body. 

Key words: CT value of vertebral body, osteoporosis, vertebral fracture, bone cement dispersion, percutaneous vertebroplasty