CASE
An 83-year-old male with an osteoporotic compression fracture of the second lumbar vertebra (L2), sustained in a fall, complained of continuing pain despite conservative treatment for the past 3 weeks. He had no neurologic deficits on physical examination. Pain was elicited when the spinous processes of L2 and L3 were palpated. The patient stated he was feeling depressed from being confined to bed and being unable to lead the active life he had enjoyed before his injury. He was referred to a specialist to see if he was a candidate for a minimally invasive procedure called vertebroplasty. The specialist ordered radiographs, a radionuclide bone scan, and an MRI of the lumbar spine to further characterize the fracture and evaluate the spinal canal (see Figure 1 and Figure 2). What do these images reveal?
DISCUSSION
Figure 1 is a radiograph demonstrating the mild compression fracture of L2. Notice its loss of height compared to the vertebral bodies above and below it. The bone scan (not shown in this article) demonstrated increased uptake of the radioisotope at L2 and L3. MRI of the lumbar spine demonstrated fluid (edema) at L2 and L3 compatible with active fractures. The fluid looks bright or whiter on a postcontrast sagittal T1 fat-saturated image (see Figure 2). Although the plain radiographs revealed the compression fracture of L2 only, the MRI demonstrated the additional fracture of L3, even though there was no loss of height or distortion of that vertebral body. The patient went on to have vertebroplasty of L2 and L3 with successful improvement of his symptoms (see Figure 3). If vertebroplasty had been performed at L2 only, he may have continued to experience severe back pain.
According to estimates, more than 700,000 osteoporosis-related compression fractures of the spine occur eachyear. Treatment is usually conservative and may include bed rest (for a short period), muscle relaxants, analgesics, physical therapy, and back bracing. Although many patients do well with conservative therapy alone, others continue to have problems with pain and disability. Before vertebroplasty was available, many of these patients had to resort to surgical intervention.
PERCUTANEOUS VERTEBROPLASTYis a minimally invasive procedure in which acrylic cement (polymethyl methacrylate) is injected into a compressed or weakened vertebra to stabilize it. The procedure is usually performed by an interventional radiologist, pain management physician, orthopedic spine surgeon, or neurosurgeon. Vertebroplasty can be performed on an outpatient basis.
Clinical evaluation and imaging are used to determine which patients maybenefit from vertebroplasty. The indications for the procedure include (1) osteoporotic compression fracture of a vertebra that occurred at least 2 weeks previously, causes moderate to severe pain, and has been unresponsive to conservative therapy; (2) painful metastasis or multiple myeloma of the vertebra (vertebroplasty is used as palliative therapy); (3) vertebral osteonecrosis; (4) reinforcement of a weakened vertebra before stabilization surgery; and (5) painful vertebral hemangioma.
Plain radiographs are usually taken first to assess for the presence and degree of compression of a vertebral fracture. CT or MRI is used to assess for any compromise to the spinal canal,to exclude other causes of back pain, and to determine the stability of the posterior wall of the vertebral body. MRI can also demonstrate edema within a vertebra, which indicates an active process. A radionuclide bone scan can demonstrate an active process as well. When an actively healing fracture is present, the bone scan will demonstrate a “hot spot” in the affected vertebra. This appears as an area that is blacker than surrounding skeletal structures because of its increased uptake of the radioisotope. Other conditions that can cause hot spots on a bone scan include metastasis and other processes with high bone turnover.
Clinically, the history and physical findings should correlate with the imaging findings with respect to the vertebral level and the symptoms of pain. Palpation of the spinous process of the fractured or affected vertebra should elicit pain or symptoms. Vertebroplasty has been shown to be most successful at improving symptoms if performed earlier (that is, on more recent fractures) rather than later.
CONTRAINDICATIONS to vertebroplasty include (1) a fracture that is healed or responding to conservative treatment; (2) diskitis, osteomyelitis, or sepsis; and (3) untreated coagulopathy. Relative contraindications are (1) a fracture older than 1 year; (2) collapse of the vertebral body of greater than 80% to 90%; and (3) significant spinal canal compromise by bone or tumor. If severe collapse of the vertebral body has occurred, spinal fusion surgery may be an option for some patients.
Vertebroplasty is not used to treat chronic back pain or herniated disks. It also does not prevent additional fractures. In fact, patients with compression fractures due to osteoporosis are at increased risk of having more fractures. The osteoporosis, therefore, should also be treated.
DURING VERTEBROPLASTY, the patient is usually given conscious sedation. Only rarely is general anesthesia utilized. The patient is placed in a prone position. Using sterile technique, the specialist places a needle into the vertebral body from a transpedicular or parapedicular approach. The cement mixture is injected into the vertebral body under fluoroscopy, so the specialist can observe as it fills the body. The same vertebral body may be accessed from both pedicles unless there is adequate cross-filling when accessing from one side. The cement hardens within the vertebral body in less than 1 hour, forming an internal cast. The procedure itself is performed in 1 to 2 hours, depending on how many levels are treated. After the procedure, the patient remains in bed 1 to 2 hours to allow the cement to set. Before discharge, the patient should be assessed for neurologic deficits, new chest pain, and relief of back pain. Many patients experience immediate pain relief. Some may require NSAIDs to ease procedure-related pain. Others may take up to 3 days to obtain relief. Approximately 75% to 90% of patients will have complete or significant decrease in symptoms. As many as two thirds will decrease or discontinue their pain medication within a few weeks following vertebroplasty.
COMPLICATIONS of vertebroplasty are uncommon and occur in fewer tha1% to 3% of patients. Some complications may be transient, including fever, nerve root irritation, hemorrhage, orworsening pain for hours after the procedure due to heat generated by the polymerization of the cement. Other complications include cement embolization to the lungs via the paravertebral venous plexus, infection, pneumothorax, paralysis, neurologic deficits, or increased back pain. Vertebroplasty does not restore the vertebral body height or shape. A procedure called kyphoplasty attempts to restore the height and shape by inflating a high-pressure balloon in the vertebral body and then filling the cavity with cement. Both procedures may benefit patients for whom conservative therapy fails and who continue to suffer with back pain and its disabling effects. JAAPA
Julie Vajnar is the department editor for Diagnostic Imaging Review and practices in a radiology group at North Oaks Health System, Hammond, Louisiana. She has indicated no relationships to disclose relating to the content of this article.