The majority of anterior vertebral column compression fractures are caused by osteoporosis, but some cases arise from benign or malignant tumors of the vertebral body. The prevalence of vertebral compression fractures in people over 70 years of age is 70%, and the prevalence in postmenopausal women is approximately 16%. For patients with anterior vertebral column compression resulting in low back pain, conventional surgical approaches are highly invasive and have long postoperative recovery times. In recent years, minimally invasive spine surgery techniques have developed rapidly, and percutaneous vertebroplasty (PV or PVP) is one of the representative treatment methods. PVP is used to treat osteoporotic vertebral compression fractures, vertebral metastases, and primary vertebral damage, with the goal of stabilizing the fractured vertebrae, relieving the osteopathic pain caused by these disorders, and improving the function of the patient’s body. Currently, it is widely used in the treatment of thoracolumbar osteoporotic compression fractures with good clinical results. PKP is developed from PVP, which uses an expandable balloon to reposition a collapsed vertebral body and create a space within the vertebral body into which PMMA is injected to restore height, strengthen the vertebral body, and relieve the patient’s pain.
Advantages of vertebroplasty.
The operation time is short, the pain relief effect is clear, and the vertebral body can be reconstructed; 2. The systemic interference to the elderly patients is light and the safety is high; 3. The postoperative recovery is fast, the complications are few, and the hospitalization time is short (generally 3-5 d); 4. The pain can be relieved in time, and the toxic side effects and dependence of taking drugs can be avoided; 5. The continued pressure deformation and fracture displacement of the vertebral body can be prevented. It can be seen that vertebroplasty is significantly better than the traditional conventional surgery.
Pain relief mechanism.
1. after bone cement injection, its mechanical effect truncates the local blood vessels, and the chemical toxic effect and the thermal effect produced during polymerization can necrosis the nerve endings of the surrounding tissues.
2. the injection of bone cement strengthens the vertebral body and reduces the stimulation of vertebral nerves in the fracture area
3. the bone cement fixes the local fracture, and local braking of the fractured vertebral body is the main mechanism of pain relief.
Vertebroplasty biomechanics.
The mechanical strength of the osteoporotic vertebral body is reduced, and the vertebral body is strengthened and enhanced by percutaneous perforation of the vertebral body with bone cement infusion. The relationship between vertebral strength and the amount of bone cement infused: experimental studies have shown that infusion of 15% of the volume of the vertebral body with bone cement can restore the strength of a fractured vertebral body to the level of an intact vertebral body, while infusion of 30% of the volume of the vertebral body with bone cement can achieve 150% of the strength of a normal vertebral body.
Although general vertebroplasty techniques emphasize infusion of as much bone cement as possible, clinical studies have failed to confirm the relationship between infusion volume and clinical outcome.
Indications.
Osteoporotic compression fractures
osteolytic and metastatic bone tumors: stabilization and pain relief
Vertebral hemangioma
Contraindications.
Severe cardiopulmonary disorders
Bleeding disorders
incomplete vertebral endplates, destruction of the middle column, spinal cord compression, etc.
pain not limited to the vicinity of the fractured vertebral body
no pressure pain in the fractured segment
Presence of neurogenic pain
Unstable fracture with posterior spinal column involvement
Posterior synostosis fractures with posteriorly protruding bone masses toward the spinal canal should not be applied
Treatment.
The optimal timing of vertebroplasty for vertebral compression fractures is inconclusive and is usually performed after failure of conservative treatment. Most investigators have performed vertebroplasty 1 to 4 months after fracture, but there is no statistical correlation between clinical outcome and time to fracture. A retrospective study found that vertebroplasty significantly reduced pain and improved mobility regardless of the time of fracture and duration of symptoms, although this study had limitations such as small sample size and retrospective nature.
For a single thoracolumbar compression fracture (>70%) caused by osteoporosis, Chin et al. used a soft pillow to reposition the patient in a hyperextended position, after which PVP or PKP could be performed. This method is based on PVP via the pedicle approach, followed by PMMA injection into the pedicle pin channel to stabilize the pedicle. In a preliminary clinical application report, Verlaan et al. performed kyphoplasty (KP) via the posterior pedicle screw system and then injected calcium phosphate cement (CPC) into 20 patients with thoracolumbar burst fractures without neurological injury within 1 w of injury, and postoperative radiographs and MRI showed that CPC was distributed within the injured vertebral body. The CPC was well distributed in the injured vertebral body, and 78% and 91% of the central and anterior heights of the injured vertebral body were restored, respectively, and cement leakage occurred in five cases, but did not cause clinical discomfort.
One author observed 12 elderly women with compression fractures of the thoracolumbar spine undergoing kyphoplasty, and measured pulmonary function and VAS scores before and after surgery. The results showed a significant improvement in pulmonary function and a decrease in VAS scores 5 d after kyphoplasty, which were significantly different from those before surgery (P < 0105). This indicates that elderly women with thoracolumbar compression fractures had significant pain relief and improved pulmonary function at 5 d after kyphoplasty.
Other authors compared the clinical results and advantages and disadvantages of balloon-expanded percutaneous kyphoplasty (PKP) with those of the Sky bone expander PKP. PKP was performed on 86 vertebral bodies in 49 patients, including 29 vertebral bodies in 24 cases in the Sky group and 57 vertebral bodies in 25 cases in the Balloon group, using the Balloon Bone Expander (Balloon group) and the Sky Bone Expander (Sky group), respectively. It was confirmed that both balloon-expandable PKP and Sky bone expander PKP had good clinical efficacy in the treatment of painful compression fractures; Sky bone expander PKP was better in single-segment vertebrae, and balloon-expandable PKP was more suitable for multi-segment vertebral fractures.
Surgery-related complications.
Complications associated with percutaneous puncture operations: injury to blood vessels, spinal cord, pleura, abdominal organs
Bone cement leakage: leakage in the spinal canal and neurogenic foramen, spinal cord compression, immediate surgical decompression, good postoperative neurological recovery, intervertebral and paravertebral bone cement leakage, generally no significant effects
In a small number of patients, PMMA cement leakage into the intervertebral space causes unrelieved back pain and requires surgical fixation of the intervertebral disc.
Cardiopulmonary complications
Pulmonary embolism: leakage of PMMA bone cement through the paravertebral vein
Mild symptoms, continue observation
severe symptoms, anticoagulation
Leakage of bone cement can be as high as
Despite the high incidence of cement leakage, only a minority of patients have clinical complications
re-fracture of the adjacent segmental vertebrae
New vertebral fractures have been reported in 12.4% of patients after vertebroplasty, with 67% of these fractures involving the adjacent vertebral body
Reason 1: The patient’s clinical condition improves quickly after vertebroplasty, resulting in new vertebral fractures as a result of participating in more activities than previously possible
Reason 2: Vertebroplasty strengthens one segment of the vertebral body, but places greater stress on other segments of the vertebral body, thereby predisposing it to re-fracture
Controversy! Prophylactic vertebroplasty.
Vertebroplasty is performed to strengthen a vertebra adjacent to a fractured vertebra without a compression fracture to prevent it from fracturing
It is believed that once a compression fracture occurs in one vertebra, the incidence of fracture in the adjacent vertebrae is significantly higher
However, the timing and extent of prophylactic vertebroplasty is not yet standardized and requires further study
Efficacy of surgery.
Recent results are positive
It is clinically proven that vertebroplasty is a simple, safe and effective minimally invasive technique that provides rapid and durable relief of pain caused by vertebral compression fractures
Long-term efficacy: to be observed and followed up
Outlook.
Although it has not been clinically used for a long time, PKP has been fully recognized for its safety and effectiveness, and has a promising application. However, PKP still needs further in-depth research, such as the accuracy of the puncture device, how the bone cement reacts with the bone interface, what are the changes in the biomechanics between the treated vertebrae and the adjacent vertebrae; the development of new safe, economic, biocompatible bone cement with low toxic side effects, and the trials of prospective randomized controlled studies.