With the extension of life expectancy and ageing of the general population, osteoporosis has become a significant health problem. Osteoporotic fractures are severe consequences of osteoporosis. Among osteoporotic fractures, vertebral compression fractures have the highest incidence. The current treatment methods for OVCFs include conservative treatment and surgical treatment. Conservative treatment for patients with long-standing back pain is not very clinically effective. PVP has been recommended for patients with compression fractures who have pain and are not satisfied with the conservative treatment results. The conventional PVP technique relies on the injection of bone cement due to external pressure to open the vertebral body. The injected bone cement cannot reach the cavity in different directions, which easily causes bone cement leakage. The success rate of PVP in the treatment of OVCFs is 89% - 93%, as reported in the literature.
In 1997, Jensen et al. described a PVP technique involving a puncture and catheterization based on the surface projection of the pedicle. With C-arm fluoroscopy, the puncture sleeve was drilled to be parallel to the upper and lower edges of the pedicle and positioned slightly forward and downward so that the tip of the puncture sleeve reached the anterior and inferior 1/3 sections of the vertebral body under lateral fluoroscopy. Clearly, this kind of puncture ultimately leads to the bone cement injection point being fixed at the anterior and lower parts of the vertebral body, but the fracture areas are not the same across patients. Clinically, it can be observed that the fracture areas in patients with OVCFs can involve the upper, middle or lower parts of the vertebral fracture body, two of these parts, or even three of these parts at the same time; when using straight-mouth push rods, it is difficult to disperse the amount of bone cement recommended by studies in the literature in the fracture area, which is located relatively far away from the point of injection of the bone cement. Thus, conventional PVP can lead to insufficient dispersion of bone cement in the fracture area in some patients. It has been reported that the clinical effect of PVP is directly proportional to the degree of diffusion of bone cement[18, 19].
To optimize the PVP technique, we improved the push rod used in PVP. With the modified PVP technique, the direction of the puncture needle is adjusted under fluoroscopy during the operation so that the tip of the puncture trocar, namely, the bone cement injection point, is positioned as close as possible to the plane of the fracture area. At the same time, a side-hole push rod was used to control the direction in which the bone cement was injected, and the fracture area was taken as the centre to inject bone cement into the nonfracture area above and below the fracture area. The modified PVP technique can diffuse bone cement well in the cancellous bone space of the vertebral body, serving as an anchor and providing improved stability. Molloy et al. observed that the filling rate of bone cement in a fractured vertebral body was significantly positively correlated with the stiffness of the vertebral body.
This study showed that there were no significant differences in intraoperative bone cement injection results between conventional PVP and modified PVP. Compared with conventional PVP, modified PVP can lead to the cement being filled in the fracture area more accurately. The cement was dispersed better in the cancellous bone space of the nonfracture area. In addition, the leakage rate of bone cement in the modified PVP group was only 24.3%, which was significantly lower than that in the control group (46.9%). Zhu et al. concluded that the leakage rate of PVP bone cement reached 58.2%. According to the relevant literature, the leakage rate of bone cement in conventional PVP surgery is 30%~70%, and 66% of postoperative complications are related to the leakage of bone cement. The full dispersion of bone cement can reduce the amount of leakage of bone cement, which also shows that the modified PVP technique could reduce the amount of leakage of bone cement to a certain extent. There were no cases of bone cement leakage to the posterior edge of the vertebral body or spinal canal. On postoperative day 3, the VAS score of the modified PVP group was better than that of the conventional PVP group, which may be because the bone cement can diffuse better in the fracture line, leading to fixation of the fractured bone trabeculae, a reduction in the micromotion of the fracture end, an improvement in the immediate stability of the postoperative vertebral body, a reduction in the stimulation of the nerve endings and, thus, pain relief.
In this study, the sample sizes of the groups are limited, which may cause deviations in the parameter measurements. Despite the above limitation, we found that modified PVP is safe and effective in the treatment of OVCFs, according to the values of relevant parameters. Compared with the traditional technique, the modified technique can lead to the sufficient diffusion of bone cement, a smaller amount of bone cement leakage, and better short-term effects. However, additional data must be collected and additional statistical analyses conducted to determine the long-term efficacy.