Vertebroplasty, as an open operation, has been used to strengthen pedicle screws and fill the defects left by tumor resection for decades. Surgery is to inject bone tissue or bone cement into the vertebral body to enhance its structural strength mechanically. In some cases, because of the high risk of open surgery, both doctors and patients stopped, so percutaneous vertebroplasty (PVP) appeared. Percutaneous vertebroplasty inherits the advantages of vertebroplasty and has no complications related to open surgery. 1984, this operation was first completed by Galibert and Deramond of university of amiens Medical Radiology Department, and 1 case of cervical hemangioma was successfully treated by percutaneous injection of PMMA, which pioneered the percutaneous vertebroplasty. Neuroradiologists and neurosurgeons in the Affiliated Hospital of the University of Lyon, France, used a slightly improved technique (18G) to inject bone cement into the vertebral bodies of 7 patients, including 2 patients with vertebral hemangioma VHs, 1 patient with vertebral metastatic tumor and 4 patients with osteoporotic vertebral compression fracture. Results Pain was relieved in 7 patients, with excellent in 6 cases and good 1 case. Kaemmerlen et al reported that this technique was used to treat spinal metastases 19. Among 20 patients with vertebral metastasis, 16 patients achieved remarkable curative effect, 2 patients were ineffective and 2 patients had complications. The author thinks that the pain osteolytic vertebral metastasis without peripedicle invasion is one of the best surgical indications for percutaneous vertebroplasty.
1994 PVP (using Deramond method) was first introduced to the United States by the University of Virginia. Since then, PVP has become a common method to treat painful spinal diseases. The application of percutaneous vertebroplasty is gradually popularized. Except vertebral hemangioma, myeloma and osteolytic metastasis, it is mostly used for patients with osteoporotic vertebral compression fracture with intractable pain. With the extension of the survival time of patients with tumor metastasis, the requirements for their quality of life and activity in the late stage of the disease also increase. In patients with spinal metastases, it is reported that PVP can relieve pain and structurally strengthen the vertebral body damaged by osteolysis, so that patients can relieve pain and continue their daily weight-bearing activities. European experience mainly focuses on the treatment of pain related to tumor (benign and malignant), while American experience mainly focuses on the treatment of pain related to osteoporotic compression fracture.
Percutaneous kyphoplasty
Percutaneous kyphoplasty (PKP) is an improvement and development of percutaneous vertebroplasty. 1999, Mark Reiley, an American plastic surgeon in Berkeley, invented an expandable bone rammer. This technique uses percutaneous puncture and balloon dilatation in the vertebral body to reset the vertebral body and form a space in the vertebral body, which can reduce the thrust required for injecting bone cement, and the bone cement is not easy to flow in it. Compared with conventional methods, this method has no difference in biomechanical properties. Clinical application shows that it can not only relieve or alleviate pain symptoms, but also obviously restore the height of compressed vertebral body, increase the stiffness and strength of vertebral body, restore the physiological curvature of spine, increase the volume of thoracic and abdominal cavity, improve organ function and improve the quality of life of patients. The inflatable bone expansion balloon (KyphXTM) developed and produced by Kyphon Company in the United States is expensive, and the improved inflatable bone expansion balloon produced by Guanlong Company in China has been used in clinic, which greatly reduces the cost and is conducive to popularization and application. A new kyphoplasty system developed by Disc-O-Tech company in Israel & mdash；; Sky bone expander system has also been applied in clinic. In addition, kyphoplasty of Sunflower system developed by A-spine Company uses four metal steel plates to restore the vertebral body, provides a stable cavity at the same time, can also control the shape and volume of the cavity, and can put capsules (Vessel-X&: reg； Angioplasty with bone cement in vertebral body will also be applied in clinic.
Percutaneous vertebroplasty and percutaneous balloon kyphoplasty are widely carried out in the world. In 2002, there were 38,000 cases of percutaneous vertebroplasty and 65,438 cases of percutaneous kyphoplasty in the United States, which were mainly used to treat osteoporotic vertebral compression fractures. The reported pain relief rate is over 90%, and there are few serious complications. Its good curative effect and high safety have been recognized by doctors and patients. Enhance vertebral body strength
The biomechanical test of 40 fresh osteoporotic patients' vertebral specimens by Bo et al. showed that the axial compressive strength and stiffness after vertebral compression fracture were 527.43N and 84.11n/mm respectively. After injecting calcium phosphate or PMMA into vertebral body, the test results showed that the calcium phosphate group was 1063. 127N, 157.2 1N/mm, and the PMMA group was 1036. 100N,/respectively. The research shows that injecting self-curing calcium phosphate cement (CPC) into vertebral body can significantly restore the mechanical properties of fractured vertebral body, and the degree of recovery is related to the amount of injected cement. The maximum strength can be twice as high as that under normal conditions, and the stiffness can exceed the original 65,438+05%. Pedicle calcium phosphate cement can also restore the strength and stiffness of vertebral body by filling fracture space and intravertebral space, increasing by 65438 06.67% respectively (P < 0.05) and11.05% (p&; lt； 0.05)。
Change spinal stability
Mermelstein found that after vertebroplasty, the compliance of vertebral motion segments in patients with osteoporotic compression fractures decreased significantly compared with that before operation, and the compliance of flexion, extension and lateral bending decreased by 23% and 26% respectively, but Kifune's research showed that the compliance of flexion, extension and lateral bending increased by 34% after compression fractures. Biomechanical experiments of cadaveric specimens show that the stress of pedicle screw can be reduced immediately after injecting self-curing artificial bone cement into the diseased vertebral body through pedicle. Mermelstein found that the flexion and extension stiffness increased by 40% after pedicle internal fixation and calcium phosphate vertebroplasty. Calcium phosphate can significantly increase the stability of the anterior column, reduce the stress acting on the pedicle, and finally enhance the stability of osteoporosis, burst fracture and pedicle internal fixation. Although the results of various studies are different, they all show that vertebroplasty has a significant impact on the stability of the spinal segment where patients with vertebral compression fractures are located.
The increase of vertebral strength and stiffness after vertebroplasty may cause another problem, that is, the load of upper and lower intervertebral discs increases (the upper intervertebral disc is more obvious), which may easily lead to intervertebral disc degeneration or fracture of adjacent vertebral bodies. The research shows that excessive stiffness can cause the redistribution of stress field and displacement field of spine to a certain extent after changing the strength of vertebral body, but the stress of adjacent vertebral bodies strengthened with CPC has no obvious effect and has little effect on adjacent intervertebral discs.
Relieve spinal pain
Micro-fracture of vertebral body and micro-motion of fracture line stimulate nerve endings in vertebral body, causing pain. In this case, percutaneous vertebroplasty can relieve pain. In this sense, percutaneous vertebroplasty is a fracture repair technique, not just a simple vertebral body filling. Almost all clinical results show that the pain relief rate of patients with osteoporotic compression fracture or old thoracolumbar fracture is as high as over 90%. The reasons are not clear, which may be as follows: (1) the microfractures in the vertebral body are stable after vertebroplasty; ⑵ Bone cement bears a considerable part of axial stress, which reduces the stimulation of fracture line fretting on nerves in vertebral body; ⑶ The sensory nerve endings in the vertebral body were destroyed.
Because PMMA has exothermic and toxic effects, it may damage nerve endings in bone, so many people think that the last factor is the main factor to relieve the pain after PMMA vertebroplasty, but it is later found that calcium phosphate vertebroplasty can also achieve the same analgesic effect, which shows that the injury of nerve endings is not the only factor, and the explanation that the pain caused by the stretching of the posterior branch of spinal nerve caused by wedge-shaped compression of vertebral osteoporosis cannot be ruled out. In China, Pu Bo et al. found that there are a large number of spinal nerve posterior branch fibers in the vertebral body, intervertebral disc and facet joints of osteoporosis rats, which may be related to instability.
In the aspect of spinal tumor, after injecting bone cement, its mechanical action can block local blood flow, and its chemical toxicity and polymerization heat can also kill nerve endings of tumor tissue and its surrounding tissues, thus achieving the effect of relieving pain and even killing tumor cells in a certain sense. Indications:
Vertebral tumor was the earliest application object of percutaneous vertebroplasty, and achieved good results. Its applicable objects mainly include:
Vertebral hemangioma
myeloma
Primary and metastatic malignant tumors of vertebral body
Benign tumor of partial vertebral body
The indications of benign tumors of vertebral body are that benign tumors lead to vertebral fracture collapse and cause pain, including eosinophilic granuloma and vertebral lymphoma. Vertebral malignant tumor, mainly osteolytic, can not only be stabilized by injecting PMMA into vertebral body, but also be diagnosed by tumor tissue biopsy.
Vertebral hemangioma, percutaneous vertebroplasty can increase vertebral strength, relieve pain and embolize tumor; Posterior laminectomy is needed when necessary, which simplifies the operation. It has been reported that decompression before and after vertebroplasty can greatly reduce the amount of bleeding. Laredo et al. divided hemangioma into two types according to imaging manifestations: invasive and potentially invasive. The main imaging manifestation of hemangioma is irregular palisade trabecula of vertebral body, which can involve the whole vertebral body and vertebral arch. The edge of the lesion can be clear or not, and it can break through cortical bone and extend to epidural space. CT and MRI can find the masses around the vertebral body.
Vertebral hemangiomas are divided into the following groups according to clinical and imaging manifestations: ① Hemangiomas with negative invasive signs but painful symptoms; ⑵ Hemangiomas with aggressive signs but no clinical symptoms; ⑶ Hemangiomas with invasive imaging signs and clinical symptoms; ⑷ Hemangiomas have invasive imaging features and symptoms of spinal cord nerve compression. The first group is the selective indication of PVP. Deramond et al reported that 90% of the cases were relieved and no recurrence of hemangioma was found. The second group is the best indication of PVP; In the third group, anhydrous alcohol was injected into vertebral body instead of bone cement to harden hemangioma and strengthen the bearing capacity of vertebral body. The neurological symptoms of most patients gradually disappeared, and some cases disappeared after image follow-up. The fourth group of hemangioma PVP is only an auxiliary means. The day before routine operation, n-butyl cyanoacrylate resin was injected into PVP focus to embolize hemangioma, which reduced intraoperative bleeding and made the operation easier.
Metastasis and myeloma are the most common osteolytic malignant tumors in the spine, which often lead to severe back pain and loss of mobility. The treatment measures depend on the number and location of vertebral bodies involved, the degree of spinal involvement, the presence or absence of neurological symptoms, the general situation of patients, the degree of pain and the degree of mobility limitation. Widely used radiotherapy can relieve more than 90% of patients' symptoms, but it usually takes 10 ~ 20 days to show the effect, and it can't maintain the stability of vertebral body. The tumor can still recur in the vertebral body after radiotherapy. The best indications of PVP in the treatment of spinal malignant tumor are local severe pain caused by malignant tumor, bed rest due to limited activity, analgesic to relieve symptoms and no invasion of dural structure in spinal canal; For vertebral compression fractures, the vertebral body should be at least 1/3 normal height, and the cortex at the back of the vertebral body need not be complete. Because vertebral malignant tumors are prone to compression fractures, PVP treatment is still a good method even if patients have no symptoms. According to the data, after PVP treatment, more than 80% patients' symptoms were obviously relieved and their quality of life was improved. After PVP is used to treat vertebral malignant tumors, radiotherapy can be used to consolidate the curative effect, because radiotherapy does not affect the physical and chemical properties of bone cement.
Myeloma is often multifocal, and it is impossible to achieve multi-segmental resection and fusion. The pain of 90% patients was relieved or disappeared within 10 ~ 14 days after radiotherapy. Moreover, radiotherapy weakens the ability of bone reconstruction, which usually begins 2 ~ 4 months after radiotherapy. The vertebral body of patients with myeloma is easy to collapse after radiotherapy, which increases the risk of nerve compression. PVP can immediately relieve pain, increase the strength and stability of the spine, correct kyphosis caused by vertebral collapse, greatly improve the quality of life of tumor patients, and is beneficial to further chemotherapy and radiotherapy.
Absolute contraindications:
(1) uncorrected coagulation disorder and bleeding constitution;
(2) allergic to anything needed for surgery.
Relative contraindications:
(1) obviously exceeds the root pain of vertebral body pain, which is caused by compression syndrome unrelated to vertebral body collapse; (2) The tumor spread to the epidural space and caused obvious spinal canal compression;
(3) Vertebroplasty is difficult to operate when the vertebral body is extensively destroyed or seriously collapsed (the height of the vertebral body is less than 1/3 of the original height);
(4) Osteogenic tumor;
(5) Processing 3 or more fragments at a time.
In the United States, percutaneous vertebroplasty and kyphoplasty are more widely used in patients with osteoporotic vertebral fractures. Details are as follows:
Indications:
(1) painful osteoporotic vertebral compression fracture, which was ineffective after drug treatment;
(2) Painful vertebral fracture related to osteonecrosis;
(3) unstable compression fracture;
(4) Multiple osteoporotic vertebral compression fractures lead to kyphosis, which affects lung function, gastrointestinal function and change of center of gravity;
(5) Chronic traumatic fracture with nonunion or internal capsule degeneration;
(6) Acute traumatic fracture without neurological symptoms.
Absolute contraindications:
(1) asymptomatic stable fracture;
(2) Patients with obvious improvement after drug treatment;
(3) Patients with no signs of acute fracture should be given preventive treatment;
(4) uncorrected coagulation disorder and bleeding constitution.
(5) The target vertebral body has osteomyelitis;
(6) allergic to anything needed for surgery.
Relative contraindications:
(1) obviously exceeds the root pain of vertebral body pain, which is caused by compression syndrome unrelated to vertebral body collapse;
(2) The vertebral canal is obviously compressed due to the retreat of the fracture block;
(3) Severe vertebral collapse;
(4) Painless stable fracture with a course of more than 2 years;
(5) Processing 3 or more fragments at a time.