Severe vertebral compression fractures is a special type of spinal compression fractures in elderly patients, and the vertebral compression generally exceeded 2/3 of the original height. Most scholars believe that such compression fracture is excessive, and that it is difficult for needle to enter vertebral body, which may cause puncture needle to perforate vertebral body, vertebral bone cement leakage, vertebral injury or needle being unable to reach the desired position. Hence, most patients received conservative treatments such as bed rest and medication unless they were combined with neurological symptoms[6, 7]. But long-term bed rest can produce complications such as pneumonia, pulmonary embolism, decubitus, malunion, or develop into chronic fracture because of poor healing. A small number of patients can develop disuse osteoporosis or become disabling and even fatal due to long-term bedridden, muscle atrophy and reduced weight-loading. Thus, scholars try to use surgical treatment for severe compression fracture[8, 9]. But it is still controversial on the puncture path and bone cement injection. Chen C reported Severe OVCFs should be candidates for PVP. The unilateral PVP can get the same clinical results with fewer complications compared with the bilateral PVP. Significant improvement on the visual analog scale and Oswestry disability index scores were noted in each group, and there were no significant differences between the 2 groups. Cement leakage was seen more in bilateral PVP[10, 11].
In this study, the authors Compared unilateral and bilateral percutaneous vertebroplasty in the treatment of severe vertebral compression fractures. and found that pain of both groups was relieved, function was well recovered, surgery process was easy and feasible, and the complication rate was low.
In the present study, the patients pain relief rate was 100%, and the puncturation success rate was 100%. During vertebroplasty process, it is generally considered that the tip of puncture needle should be in front of the 1/3 of the vertebral body. But needle can only reach the middle or the posterior 1/3 of the vertebral body in patients with severe vertebral compression. This study observed that, even if the needle could not reach into the middle or even less than 1/2 of the vertebral body, bone cement can be well distributed and have no significant leakage within the vertebral body because of the cement fluidity under severe osteoporosis condition. In this study, needle can only reach the middle or posterior 1/3 vertebral body in 4 vertebrae, but the authors used spiral pressure to slowly inject bone cement under the C-arm fluoroscopy monitoring, without leakage occurrence. Moreover, some patients had good bone cement distribution within the vertebral body. The study observed that the needle position was not associated with whether the bone cement dispersed to the contralateral side. However, MRI in this study showed that in the 4 patients who failed to spread bone cement to the contralateral side, STIR had low signal change on vertebral body and bone cement was poorly dispersed, while bone cement was better dispersed in vertebrae with high signal change on STIR shown by MRI. But even in the 4 patients who failed to spread bone cement to the contralateral side, the pain was relived too.
During surgical process, when needle failed to reach the posterior edge of the vertebrae under lateral perspective observation, the anteroposterior needle tip can not exceed the medial border of the pedicle. Meanwhile, it should be noted that the needle should pass through the vertebra and try not to destroy the superior and inferior endplate. Theoretically, larger amount of bone cement injection can obtain greater vertebral intensity support and better clinical effect. However, clinical studies have shown that bone cement injection volume is not directly related to the clinical analgesic effect, and the amount of bone cement injection had no effect on vertebral fracture within 1 year.
Cement leakage: calcium phosphate cement (CPC) is biodegradable and its solidification temperature is low, which can reduce thermal damage to adjacent tissue even leakage occurs. Kaufmann et al. reported that the injected dose was not significantly related with the therapeutic effect of bone cement. In PKP, if the injection dose of bone cement was over the maximum volume of the cavity formed by balloon expansion, the pressure within the vertebral body would be suddenly increased, and the probability for bone cement leakage was larger. Belkoff et al. suggested that, 2 ml injection of bone cement could restore the vertebral strength. Studies showed that 3 ml of thoracic injection and of 5 ml lumbar injections could obtain good efficacy. However, previous studies have reported that PVP for treating severe vertebral compression fractures had higher cement leakage rate. Marc et al. reported that 34 of 37vertebrae occurred vertebral bone cement leakage, with the leakage rate of 91.9%[13, 14]. Wilfred reported the bone cement leakage rate of 43% and Casey et al. the leakage rate of 72%. Patients with bone cement leakage had no clinical signs of leakage, and no other complications, which may be related to the amount of bone cement injected. In the reported studies with high leakage rate which used vertebroplasty for severe compression fracture surgery, the amount of injected bone cement was large, and was generally higher than 6 ml. In this study, most patients were injected with 1–4 ml of bone cement injection. In this study, only 4 of 32 vertebrae were found with bone cement leakage in group A, 9 of 32 vertebrae were found with bone cement leakage in group B.the proportion of CPC leakage was not high, with the leakage rate of 12.5% in group A, 27.7% in group B. This study observed that even small doses of bone cement injection can get good results and significantly reduce the risk of leakage in patients with severe compression fractures due to small vertebral space.
In summary,both unilateral and bilateral vetebral pedicle approach for severe vertebral compression fractures, preoperative radiologic assessment and bone cement injection under C-arm guidance in percutaneous vertebroplasty can obtain satisfactory results.PVP by unilateral vertebral pedicle approach in treating severe vertebral compression fractures can significantly relieve pain and promote functional recovery, which has advantages such as convenient operation and low complication rate.