Percutaneous vertebroplasty (PVP) is a minimally invasive spine surgery technique that involves percutaneous injection of cement into the vertebral body through the pedicle or external pedicle to increase strength and stability, prevent collapse, relieve pain, and even partially restore vertebral body height. Vertebroplasty has been used for decades as an open procedure to augment the pedicle screw and to fill the defect left after tumor resection. The procedure involves percutaneous vertebroplasty in which bone tissue or bone cement is injected into the vertebral body to mechanically strengthen its structure. For some cases, percutaneous vertebroplasty (PVP) emerged because the risks of open surgery were too great and stopped the doctor and patient in their tracks. Percutaneous vertebroplasty inherits the advantages of vertebroplasty without the complications associated with open surgery. This procedure was first performed by Galibert and Deramond at the Department of Medical Radiology, University of Amiens, France, in 1984, where a patient with cervical 2 vertebral hemangioma was successfully treated with percutaneous injection of polymethyl-methacrylate PMMA, pioneering percutaneous vertebroplasty. Using a slightly modified technique (18G), neuroradiologists and neurosurgeons at the University Hospital of Lyon, France, injected bone cement into the vertebral bodies of seven patients, two of whom had vertebral hemangiomas (VHs), one had a metastatic spinal tumor, and four had osteoporotic vertebral compression fractures. In 1989, Kaemmerlen et al. reported the use of this technique for the treatment of vertebral metastases. 16 of 20 patients with vertebral metastases achieved significant results, 2 were ineffective, and 2 had complications. The authors concluded that painful osteolytic metastases without periprosthetic invasion are one of the best indications for percutaneous vertebroplasty. PVP (applying Deramond’s method) was first introduced to the United States by the University of Virginia in 1994. Since that time, PVP has become a common treatment for painful vertebral disorders. In recent years the use of percutaneous vertebroplasty has gradually spread and is more commonly used in patients with osteoporotic vertebral compression fractures with intractable pain, in addition to spinal hemangiomas, myeloma, and osteolytic metastases. As the survival time of patients with tumor metastases increases, so do their requirements in terms of quality of life and being able to be active in the final stages of the disease. In patients with spinal metastases, PVP has been reported to relieve pain and structurally strengthen the osteolytically damaged vertebrae, allowing patients to experience less pain and to continue daily weight-bearing activities. European experience has focused on the treatment of tumor-related pain (both benign and malignant), while American experience has focused on the treatment of pain associated with osteoporotic compression fractures. Percutaneous kyphoplasty (PKP) is a modification and development of percutaneous kyphoplasty. In 1999, Mark Reiley, a Berkeley orthopaedic surgeon, developed an expandable expansion balloon (KyphXTM , Inflatable Bone Tamp), which uses a percutaneous puncture of the vertebral body to reposition the vertebral body and create a space inside the vertebral body, thus reducing the amount of thrust required to inject the bone cement and making it less likely to flow when placed inside. Compared with conventional methods, there is no difference in biomechanical properties between the two, and clinical application shows that it not only relieves or alleviates pain symptoms, but also significantly restores the height of the compressed vertebral body, increases the stiffness and strength of the vertebral body, restores the physiological curvature of the spine, and increases the volume of the thoracoabdominal cavity and improves the function of the organs, thus improving the quality of life of patients. The expandable bone expansion balloon (KyphXTM) developed and produced by Kyphon in the United States is expensive, but the improved expandable bone expansion balloon produced by Guanlong in China has been used in clinical practice, which is much less expensive and beneficial to promote its application. Recently, a new type of vertebral body kyphoplasty system developed by Israel Disc-O-Tech—Sky Bone Expender system has also begun to be used in clinical practice. In addition, A-spine’s Sunflower system, which uses four metal plates to reposition the vertebral body and provide a stable cavity for kyphoplasty, and the Vesselplasty technique, which controls the shape and volume of the cavity and allows a capsule (Vessel-X®) to be placed in the vertebral body and filled with bone cement, will also be used in the clinic. In 2002, 38,000 percutaneous vertebroplasty and 16,000 percutaneous kyphoplasty procedures were performed in the United States, mainly for the treatment of osteoporotic vertebral compression fractures, with reported pain relief rates of more than 90% and few serious complications, and their good efficacy and high safety have been recognized by the majority of doctors and patients. Table of contents Mechanism (a), enhancement of vertebral body strength Biomechanical testing of vertebral specimens from 40 fresh osteoporotic patients by Bo et al. showed that their axial compression strength and stiffness after vertebral compression fracture were 527 ±43N, 84 ±11N/mm, respectively; while the test results after intravertebral injection of calcium phosphate or PMMA showed that the calcium phosphate group was 1063 ±127N, 157±21N/mm, respectively, and 1036±100N, 156±8N/mm, respectively, in the PMMA group, and CT examination showed good intravertebral body cement filling, except for the posterior part of the vertebral body, which was 85-95% filled in the calcium phosphate group and 79-90% filled in the PMMA group. It has been shown that intravertebral injection of self-curing calcium phosphate cement (CPC) can significantly restore the mechanical properties of the fractured vertebral body, and the degree of restoration is related to the amount of injected bone cement, and its strength can reach up to two times of the normal condition, while the stiffness can exceed about 15% of the original; after vertebral fracture, the fracture is filled with CPC via the pedicle. The strength and stiffness of the vertebral body can also be restored by filling the fracture space and intravertebral space with CPC after vertebral fracture, increasing by 16.67% (P<0.05) and 11.05% (P<0.05), respectively. (ii) Modification of vertebral body stability Mermelstein found that after vertebroplasty for compression fractures in osteoporotic patients, the compliance of the vertebral body motion segments in which they were located was significantly reduced compared to the preoperative period, with flexion-extension and lateral bending compliance decreasing by 23% and 26%, respectively, but Kifune’s study showed that after vertebral compression fractures, flexion-extension and lateral bending compliance increased by 34% compared to the pre-fracture period. Biomechanical experiments on cadaveric specimens have shown that self-curing artificial bone cement injected into the diseased vertebrae via the pedicle immediately reduces the stress on pedicle screws. mermelstein found a 40% increase in flexion-extension stiffness after internal fixation of burst fractures, calcium phosphate vertebroplasty, and calcium phosphate significantly increased the stability of the anterior column and reduced the stress acting on the pedicle, ultimately causing osteoporotic, burst fractures and enhanced stability after internal arch fixation. Although the results of the studies vary, they all show that vertebroplasty has a significant effect on the stability of the spinal segments in patients with vertebral compression fractures. An additional problem that may occur with increased strength and altered rigidity of the vertebral body after vertebroplasty is the increased loading of the upper and lower discs (more pronounced in the upper disc), which can lead to disc degeneration or fracture of the adjacent vertebral body. Studies have shown that after the change in vertebral body strength, excessive stiffness can, to a certain extent, cause redistribution of the spinal stress and displacement fields, but strengthening of the vertebral body with CPC has no significant effect on the stress of the adjacent vertebral body, and the effect on the adjacent discs is also small. (iii) Relief of spinal pain Minute fractures of the vertebral body and micro-movement of the fracture line cause irritation of the nerve endings in the vertebral body causing pain, and percutaneous vertebroplasty can produce excellent pain relief in this case. In this sense, percutaneous vertebroplasty is a fracture repair technique, not just a mere filling of the vertebral body. Almost all clinical results show pain relief rates of more than 90% in patients with either osteoporotic compression fractures or old thoracolumbar fractures, for reasons for which there is no definite explanation, and which may lie in the following: (1) microfractures within the vertebral body are stabilized after vertebroplasty; (2) the bone cement takes up a significant portion of the axial stress, thus reducing the irritation of the nerves within the vertebral body by micromovements of the fracture line. (3) The intravertebral sensory nerve endings are destroyed. Because of the exothermic and toxic effects of PMMA, which may damage the nerve endings in the bone, many people initially thought that the pain relief after PMMA vertebroplasty was mainly due to this last factor, but later it was found that calcium phosphate vertebroplasty could also achieve the same pain relief effect, which shows that the damage effect on the nerve endings is not the only factor, and the previously thought explanation of pain caused by wedge compression of vertebral osteophytes causing posterior spinal nerve branches The explanation of pain caused by distension of the posterior branch of the spinal nerve due to wedge compression of the vertebral body cannot be ruled out either. In China, Po et al. found a large distribution of posterior spinal nerve fibers in vertebrae, intervertebral discs and small joints of osteoporotic rats, which may be related to instability. In the case of vertebral tumors, after injecting bone cement, its mechanical effect can interrupt local blood flow, and its chemical toxic effect and polymerization heat can also cause necrosis of nerve endings in tumor tissues and their surrounding tissues to achieve pain relief, and even have the effect of killing tumor cells to some extent in a sense.