In our study, the compression improvement of vertebral front edge and vertebral center and the correction degree of kyphosis were obviously improved postoperatively compared with preoperatively. The VAS had significantly decreased at 1 day postoperatively, and the decreased sustained at the last follow-up. Therefore, PVP combined with postural reduction technique can effectively restore vertebral height, improve kyphosis, relieve pain and increase living quality of patients for the management of Kümmell’s disease. PVP with appropriate volume of the injected bone cement can effectively restore strength and stability of the fractured vertebral body.
Currently, there is no uniform standard for the amount of bone cement injection. Some scholars believed that the lower dose of bone cement can restore the mechanical properties of the fractured vertebral body, and the volume of bone cement has no obvious correlation with the analgesic effect . 1.5 ml bone cement injected in the fractured vertebral body can obtain satisfactory analgesic effect . However, some scholars held the opposite view that bone cement should be injected to make a higher filling rate of the vertebral body, which helps to restore the strength and rigidity of the vertebral body and obtains better clinical outcomes . Besides, the volume of bone cement perfusion was related to the analgesic effect . The analgesic effect of PVP was mainly due to the restoration of the stability of the fractured vertebrae after the strengthening of bone cement . Furthermore, the strength of the fractured vertebral body can be restored by filling about 2 ml bone cement or 16% of the body volume, and the stiffness can be restored by filling about 4 ml bone cement or 24% of the vertebral body volume . In our study, the bone cement that was injected by the side opening guide needle can be injected into the fissures and cavities of the vertebral body. The injection volume was 2.7-8 ml, with an average of 5.38 ± 1.33 ml, which had reached the requirement of restoring the strength and stiffness of the vertebral body. So, the pain relief was satisfactory after the operation.
Kümmell’s disease is a special type of osteoporotic vertebral compression fractures. The cracks and cavities will expand or compress as the body position moves. So, the postural reduction can effectively perform the reduction of fractured vertebral body and restore its height without further use of the balloon to expand the vertebral body. Moreover, the severely compressed Kümmell’s disease, after balloon dilation, will further destroy the integrity of the vertebral bone and increase the number of cracks, which may increase the risk of bone cement leakage . Zhang et al.  compared and evaluated the safety and efficacy of PVP and percutaneous kyphoplasty (PKP) for the management of Kummell’s disease, which found that the correction of Cobb’s angle between two groups had no significant differences. Furthermore, Yu et al.  found that cement leakage occurred in PKP group (3/13 cases) was higher than in PVP group (1 cases/7 cases). The priming volume of cement in PVP group (6.40 ± 0.94 ml) also larger than in PKP group (5.46 ± 1.09 ml). The vertebral height restoration and kyphotic improvement, VAS of low back pain and ODI were no significant differences between two groups. Zhang et al.  reported that the VAS and anterior vertebral height in both PVP group and PKP group had significantly improved at 1-day postoperatively, and the improvement sustained at the final follow-up, but there were no significant differences between the PVP and PKP groups. Therefore, the postural reduction can effectively restore the degree of vertebral compression and kyphosis. PKP, compared with PVP, has no obvious advantages in restoring vertebral height, correcting kyphosis and relieving pain on the treatment of Kümmell’s disease. PVP is more economical and can be considered a preferred method of treatment with more clinical value.
The most common complication of PVP is bone cement leakage. It is easy for the bone cement to leak through the vertebral veins, fractured cracks, but causing clinical symptoms is less common . The amount of bone cement injected was positively correlated with the occurrence of bone cement leakage . However, some scholars believed that only the degree of compression of the vertebral body before surgery and the presence of fissures in the cortical bone were related factors of bone cement leakage . In our experience, accurate puncture intraoperatively is an effective measure to prevent bone cement leakage. During the operation, it is forbidden to break through the inner wall of the pedicle into the spinal canal for the pursuit of the so-called optimal position. The prevention of the too thinning bone cement, a proper amount of bone cement, and the repeating fluoroscopy intraoperatively can effectively reduce the incidence of bone cement leakage. When the bone cement was fully dispersed in the vertebral body and continuing injection could not be further spread, surgeon should terminate the injection of bone cement.
PVP can quickly relieve pain for most patients with acute or subacute osteoporotic vertebral fractures . Park et al.  reported that the mean VAS score significantly decreased after PVP and was maintained through to the final follow-up. However, cement leakage was observed in 26.3% without clinical symptoms. Ren et al.  observed that the VAS scores in both unipedicular and bipedicular PVP were lowered at 1d postoperatively, 3 months postoperatively and at the final follow-up compared to in pre-operation. In our study, the VAS scores were significantly improved at each time points postoperatively compared with in pre-operation, which confirmed that PVP surgery has a definite and sustained analgesic effect for the treatment of Kümmell’s disease.
Limitations of this study included retrospective nature, low patient numbers, single center, lack of control, and randomization. More and multi-center clinical studies are still needed to further evaluate this method and compare it to PKP control method or non-operative group.