Percutaneous Vertebroplasty 

Vertebroplasty is a minimally invasive, image-guided therapy used to relieve pain from a vertebral body fracture. It has been used for osteoporotic or malignant fractures. Initially, the major indication was treatment of spinal hemangiomas, as described in 1987 by Galibert et al.^[1] With experience, other indications have emerged. Vertebroplasty can increase patient mobility, decrease narcotic needs, and prevent further vertebral collapse.

Percutaneous vertebroplasty (PVP) usually involves percutaneous injection of a cement, polymethylmethacrylate (PMMA), into the vertebral bodies. Occasionally, PMMA has been placed manually into vertebral lesions during open surgical operations.

For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center. Also, see eMedicine's patient education article Vertebral Compression Fracture.

Percutaneous vertebroplasty is indicated for painful osteoporotic or neoplastic vertebral compression fractures refractory to medical therapy.

Osteoporotic vertebral fracture

Osteoporosis is complicated by vertebral fracture that occurs spontaneously or is caused by minor trauma (see eMedicine's Osteoporosis and Spinal Cord Injury article for more details). In the United States, the incidence of compression fractures is more than 500,000 patients per year, which is higher than the incidence of hip fractures. Lifetime risk of osteoporotic vertebral fracture is 16% in women and 5% in men.^[2]

These vertebral fractures are often highly painful and are treated with immobilization, analgesic drugs, and specific treatment of osteoporosis. Immobilization increases demineralization. Initial symptoms tend to disappear in 4-6 weeks. In spite of long-term medical treatment, some patients have severe, persistent, incapacitating pain. Later consequences of vertebral fracture are reduced height, kyphosis, and chronic back pain.

Multiple retrospective and prospective studies have favorably compared vertebroplasty to medical management. The VERTOS study prospectively compared osteoporotic compression fracture treatment of 18 patients with vertebroplasty to 16 patients with optimal medical management.^[3] This study found significant short-term improvement in pain relief and function in the vertebroplasty group.^[3] These results were confirmed with the Vertos II larger prospective randomized trial (101 patients were treated with vertebroplasty and 101 were treated with conservative management).^[4]

However, 2 widely discussed recent studies comparing vertebroplasty to sham procedures demonstrated no significant improvement with vertebroplasty.^{[5, 6]} This mixed evidence has sparked considerable debate as to the appropriate role of this procedure.

Spinal tumors

In painful vertebral metastasis (ie, previously untreated), radiotherapy is useful in 70% of patients to alleviate spinal pain, but this effect is delayed and may require 2-6 weeks. Vertebroplasty is a palliative treatment that typically provides more immediate analgesia.

Vertebral hemangioma

Vertebroplasty has been used successfully in severe focal spinal pain with radiologically unaggressive vertebral (body) hemangioma.

Absolute contraindications^[7]

• Asymptomatic fracture
• Active osteomyelitis of the target vertebra
• Uncorrectable coagulopathy
• Allergy to vertebroplasty cement or opacifying agent

Relative contraindications^[7]

• Significant central canal narrowing from retropulsion of bony fragment or epidural tumor
• Ongoing systemic infection
• Myelopathy or radiculopathy from fracture level

Equipment

Multiple vertebroplasty kits are available. A Stryker precision delivery system costs approximately $600-700; a physician can customize it for $200. Materials include the following:

• Needle, 6 in (DBMNJ1106-11G, MD Technologies)
• PMMA cement (Howmedica Simplex)
• Barium (opacifying agent) - Sterile barium sulfate, 6-g packets (Bryant Corporation)
• Luer-Lok syringes, 1 mL

Preprocedure patient evaluation

Confirm appropriate history and perform a brief physical examination to confirm the appropriateness of the procedure (of note, localizing tenderness on palpation is not associated with superior vertebroplasty response^[8] ).

Review the patient's record, including plain films and MRI, to identify the vertebra to be injected. Exclude significant central canal narrowing or signs of infection on MRI. Double check vertebral counting, particularly with thoracic lesions.

Obtain informed consent.

Setup and positioning

Procedure time varies from 30-120 minutes.

• Conscious sedation (midazolam and fentanyl) and local anesthesia are used in almost all patients.
• Prophylactic antibiotics should be considered.
• Place the patient in the prone position.
• Align posterior ribs to obtain a good lateral view.
• On the anteroposterior (AP) view, find the obliquity that projects the pedicle over the upper outer third of the vertebral body. Mark this point.

Radiation exposure

A study was performed evaluating patient and operator radiation exposure during 11 vertebroplasty cases. Patient effective doses were estimated at 34mGy with average fluoroscopy times of 28 minutes (in comparison, a typical CT abdomen and pelvis effective dose is 8-14 mGy). Operator exposures were highest to the hands and chest, although there was a decrease in occupational dose by 76% with the use of mobile shielding. It was estimated that an operator could perform 150 procedures annually before exceeding annual dose constraints.^[9]

Needle placement

Use lidocaine for local anesthesia. Use a spinal needle to anesthetize the periosteum.

Confirm proper needle path with AP and lateral fluoroscopic views.

For large pedicles (ie, lumbar, lower thoracic), use an 11-gauge needle; use a 13-gauge needle for smaller pedicles (ie, midthoracic).

While maintaining good back tension with a large clamp, use a sterile hammer to gently tap the needle. Direct the needle into the vertebral body, using AP and lateral views for verification.

• For a unipedicular approach, advance needle into the anterior third of the central vertebral body.
• For a bipedicular approach, advance needles into the midportion of the hemivertebrae.
• A parapedicular approach may be considered as well.

Polymethylmethacrylate mixing and injection procedure

Mix polymethylmethacrylate (PMMA) and barium sulfate (opacifying agent) as per the manufacturer's instructions. Slowly inject this mixture until the vertebral body is well filled, making certain to stop before PMMA leaks posteriorly into the epidural area or significantly fills a vein.

Although many practitioners attempt to fill the vertebral body as completely as possible, note that pain relief is not associated with cement volume.^[10]

Postprocedure care

Keep patients on bed rest for 1-2 hours.

Administer analgesics for postoperative pain and muscle relaxants for significant muscle spasms, as needed.

Ensure that the patient's primary care physician is medically managing osteoporosis; if he or she is not, management must be instituted. Without systemic osteoporosis therapy, 20% of patients with a fracture develop a second fracture.^[11] Treatment for osteoporosis includes DEXA scans, lifestyle modifications (smoking cessation, alcohol moderation, exercise), dietary supplementation (calcium, vitamin D), and medical management (antireabsorbatives).^[12] See eMedicine's Osteoporosis article for more details.

Chiras et al reported incidents and complications in 274 patients.^[13] These complications were more common with malignant spinal tumor (10%) and vertebral hemangioma (2-5%) than with osteoporotic lesions (1-3%).

Major complications occur in < 1% of patients treated for osteoporosis-related compression fractures; minor complications occur in < 2% of these patients. In patients with neoplastic involvement, major complications occur in < 5% and minor complications occur in approximately 10%.

Complications include the following:

• Neurologic defect (from central canal or neural foraminal narrowing)
• Fracture of vertebra, rib, or sternum (from positioning on table or placement of needle)
• Infection
• Allergic reaction
• Pulmonary embolus
• Hemorrhage
• Pneumothorax or hemothorax

If a patient experiences new radicular pain, a CT scan may show migration of polymethylmethacrylate (PMMA) into the epidural venous plexus. New vertebral region pain may be evaluated with MRI to exclude adjacent fracture. Chest pain may be evaluated with a rib series or CT pulmonary angiogram to exclude rib fracture or pulmonary embolus. Severe back pain can indicate a fractured pedicle or transverse process, which is observed easily on CT scan. Paralysis has been reported but is very uncommon. Precautions should be taken while injecting above L1, with attention to the posterior vertebral body wall; do not allow PMMA to flow into the epidural venous plexus.

Reports are mixed as to whether vertebroplasty predisposes patients to develop additional vertebral fractures.^[14]

Percutaneous vertebroplasty is a minimally invasive procedure with promising results for the treatment of vertebral fracture. It provides significant pain relief with the potential for improving functional outcome.