What Is Percutaneous Vertebroplasty and How Does It Work?

Percutaneous vertebroplasty is a minimally invasive procedure in which a doctor injects medical-grade bone cement through a needle into a fractured spinal vertebra, typically to relieve pain from osteoporotic compression fractures. Developed in France in the 1980s, it became one of the most commonly performed spinal procedures worldwide before a pair of high-profile sham-controlled trials in 2009 threw its effectiveness into serious question. The debate that followed reshaped clinical practice and remains unresolved in some respects, making vertebroplasty one of the more genuinely controversial procedures in modern spine medicine.

How the Procedure Works

You lie face down on a procedure table, and the doctor uses live X-ray imaging (fluoroscopy) to guide a large-bore needle through the skin of your back, through the pedicle of the fractured vertebra, and into the vertebral body itself. Local anesthesia numbs the skin and tissue along the needle path; some patients receive light sedation as well. Once the needle tip is confirmed to be in the correct position inside the vertebral body, bone cement is mixed and injected while still in a semi-liquid state. The cement used is almost always polymethyl methacrylate, or PMMA, the same acrylic polymer used in joint replacements. Within about ten to fifteen minutes the cement hardens, stabilizing the fracture internally.

The procedure typically takes under an hour per vertebra and is usually done as an outpatient visit or with a single overnight stay. Many patients report dramatic pain relief within hours. That rapid response, combined with the relative simplicity of the technique, drove explosive growth in vertebroplasty use through the 2000s. But how much of that pain relief comes from the cement itself, and how much from other factors, turned out to be a harder question than anyone expected.

The Sham Trial Controversy

In 2009, two randomized trials published in the New England Journal of Medicine compared vertebroplasty to a sham procedure in which patients received local anesthesia and needle placement but no cement. Both found that vertebroplasty provided no meaningful advantage over the sham at any time point. One trial reported pain reductions of 2.6 points in the vertebroplasty group versus 1.9 points in the sham group on a ten-point scale, a difference that was not statistically significant at three months or at any other follow-up visit.¹ The results stunned spine specialists. Both groups improved substantially from baseline, suggesting that something other than the cement itself, whether it was the local anesthetic, the placebo effect, or natural healing, was doing much of the work.

A later sham-controlled trial, VERTOS IV, confirmed these findings. At every follow-up point through 12 months, pain scores improved in both the vertebroplasty and sham groups, but the differences between groups were small and never reached statistical significance.² The clinical implications were swift: the American Academy of Orthopaedic Surgeons issued guidelines recommending against vertebroplasty for osteoporotic fractures, and Medicare billing for the procedure dropped sharply starting in 2009 and continued declining through at least 2014, even after more favorable studies appeared in the following years.³

Critics of the sham trials argued that the study designs were flawed in important ways. Both enrolled patients with fractures of widely varying ages, some several months old, when natural healing may have already begun. They also included patients with relatively moderate pain levels, potentially washing out any real effect. The counterargument from vertebroplasty proponents was not that the sham trials were wrong in their populations, but that they were testing the procedure in the wrong patients.

When Timing and Patient Selection Change the Answer

The strongest evidence in vertebroplasty’s favor comes from trials that focused on patients with severe pain and recent fractures. The VERTOS II trial, an open-label randomized study, enrolled patients whose fractures were six weeks old or less and whose pain had not responded to conservative treatment. At every time point through a year, pain relief in the vertebroplasty group was significantly greater than in the conservative treatment group.⁴ Similarly, the blinded VAPOUR trial, which used a sham control but selected patients with fractures of three weeks or less, found that vertebroplasty produced meaningfully better outcomes. A critical review of this literature concluded that the evidence supports using vertebroplasty in patients with severely painful fractures of three weeks’ duration or less.⁵

An open-label randomized trial comparing vertebroplasty to optimal medical management found a pain difference of about three points on a ten-point scale at one week, along with restoration of vertebral body height averaging 8 mm and an 8-degree improvement in spinal alignment. The rate of new fractures was also lower in the vertebroplasty group, at about 2% compared to roughly 13% with medical management alone.⁶ A meta-analysis pooling data from multiple trials found that vertebroplasty was associated with significantly greater pain relief, better daily function, and higher quality of life compared to conservative treatment.⁷

The honest read of the evidence is that vertebroplasty probably works well for a specific patient profile: someone with a fresh, acutely painful osteoporotic compression fracture that has not responded to a short course of pain management. For patients with older fractures, milder pain, or less clear imaging findings, the procedure appears to be no better than a placebo injection. The disagreement in the literature is less about whether the cement does anything, and more about who should get it and when.

What the Cement Does to the Spine Mechanically

When PMMA cement hardens inside a fractured vertebra, it dramatically changes the mechanical properties of that bone. A cadaveric study found that filling just 14% of a vertebral body (about 3.5 cubic centimeters of cement) was enough to restore its stiffness to pre-fracture levels. But filling 30% of the vertebral body increased stiffness more than 50% above what it was before the fracture.⁸ That overshoot is where problems begin. A vertebra that is dramatically stiffer than its neighbors creates an uneven distribution of forces during normal spinal loading.

Finite-element modeling studies have shown that cement augmentation decreases stress within the treated vertebra but can increase stress on the endplate regions of adjacent vertebrae by a small but meaningful amount.⁹ Cadaveric biomechanical work tells a complementary story: a vertebral fracture reduces pressure inside the disc at the fractured level to roughly half of normal, and vertebroplasty partially reverses this, restoring disc pressure to about three-quarters of baseline at both the treated and adjacent levels.¹⁰ The stiffness mismatch between a cement-filled vertebra and the weak osteoporotic bone next door has been proposed as one factor driving fractures at adjacent levels after the procedure. The high compressive stiffness of PMMA bone cement is widely discussed as a potential contributor to those adjacent fractures.¹¹

Adjacent Vertebral Fractures After Vertebroplasty

New fractures in the vertebrae immediately above or below a treated level are a recognized concern. A retrospective study of postmenopausal women who underwent vertebroplasty or kyphoplasty found that roughly 9% experienced an adjacent vertebral fracture. Independent risk factors included a prior history of osteoporotic compression fracture, lower bone density as measured by CT scan, and lower body mass index.¹² Adjacent fractures also tend to occur earlier than fractures at more distant spinal levels, typically within a year or so of the procedure, while remote fractures take longer to appear.¹³

What remains debated is how much of this is caused by the cement and how much reflects the natural progression of osteoporosis. These patients already have fragile spines, and compression fractures in osteoporotic patients tend to cluster regardless of treatment. Still, the biomechanical evidence showing increased stress transfer to adjacent vertebrae has led to interest in developing lower-stiffness cements that more closely match osteoporotic bone. Research groups have experimented with modified PMMA formulations that reduce the elastic modulus of the cement to lessen stress concentration on surrounding bone tissue.¹⁴ Additional risk factors for refracture include older age, cement leakage during the initial procedure, poor cement distribution within the vertebral body, and comorbidities like hypertension and chronic kidney disease.¹⁵

Cement Leakage and Other Complications

The most common complication of vertebroplasty is cement leakage, where liquid PMMA escapes outside the vertebral body before it hardens. The detection rate depends heavily on how you look for it. Plain X-rays miss many leaks, while CT scans reveal that small asymptomatic leaks are actually quite common.¹⁶ Most leaks are harmless: a small amount of cement seeps into surrounding soft tissue or into the disc space without causing symptoms. But in rare cases, cement can leak into the spinal canal, press on nerves, or enter the venous system and travel to the lungs.

Pulmonary cement embolism, in which cement fragments reach the pulmonary arteries, has a reported incidence ranging from roughly 2% to 26% depending on the study and the imaging used to detect it.¹⁷ The vast majority of these are asymptomatic and discovered incidentally on imaging done for other reasons. One case report described a patient whose CT happened to reveal cement in the pulmonary trunk and both pulmonary arteries, yet she had no symptoms and required no treatment.¹⁸ Symptomatic pulmonary cement embolism is much rarer but can be life-threatening.

Even more unusual is intradural cement leakage, where cement enters the membrane surrounding the spinal cord. A case report described a patient who developed progressive leg weakness and urinary incontinence five years after vertebroplasty, ultimately found to be caused by cement that had leaked into the dura during the original procedure.¹⁹ These dramatic complications, while rare, underscore the importance of careful fluoroscopic monitoring during cement injection and stopping immediately if leakage is observed.

High-Viscosity Cement and Reducing Leakage

One of the most practical technical advances in vertebroplasty has been the development of higher-viscosity bone cements. Traditional low-viscosity PMMA flows easily but also leaks easily. High-viscosity formulations are injected in a more paste-like state, which makes them less likely to migrate outside the vertebral body. A meta-analysis comparing the two found that high-viscosity cement reduced the overall leakage rate by roughly 77%, with the benefit most pronounced for leaks into the disc space, paravertebral tissue, and peripheral veins.²⁰ A head-to-head clinical study of mid-thoracic fractures found that high-viscosity cement allowed a larger volume to be injected while simultaneously producing fewer leaks and better postoperative pain relief.²¹ An earlier study using a specific high-viscosity PMMA system found venous leaks in only about 8% of treated vertebrae, compared to 41% with conventional cement.²²

Researchers have also explored alternatives to PMMA entirely. Calcium phosphate cements are biocompatible and can promote bone regeneration, but they have significant practical drawbacks: lower compressive strength, slower curing, higher cost, and a tendency to fracture under load. These limitations have kept calcium phosphate cements to niche use, and at least one randomized trial found that a calcium phosphate cement was unsuitable for routine use in vertebral augmentation because of its poor resistance to the forces acting on the spine.²³

Vertebroplasty Versus Kyphoplasty

Kyphoplasty is a related procedure in which a balloon is inflated inside the vertebral body to create a cavity before cement is injected. The idea is that the balloon can restore some of the lost vertebral height and correct the forward curvature (kyphosis) that compression fractures cause. Biomechanical studies show that kyphoplasty is initially better at restoring height and reducing kyphotic deformity, but these gains tend to be lost over time with repetitive spinal loading.²⁴ A prospective comparative study confirmed that height restoration at one year was significantly greater in kyphoplasty patients.²⁵

In terms of pain relief and functional improvement, both procedures perform similarly. Kyphoplasty is generally more expensive because of the balloon device. It may also carry a slightly lower cement leakage rate because the cavity created by the balloon provides a contained space for the cement to fill. For most patients, the choice between the two comes down to how much height loss has occurred and whether there is significant kyphotic deformity worth trying to correct.

Long-Term Outcomes

While most studies of vertebroplasty track patients for one to two years, a few have looked further out. A control study with an average follow-up of ten years found that patients maintained consistently improved quality of life and sustained pain relief over the full decade.²⁶ A more recent cohort study tracking outcomes at two years found substantial improvements in disability scores, physical function, and pain, but also found that increasing age independently predicted worse functional recovery. For every ten-year increase in age, physical function scores were meaningfully lower at two years.²⁷ The variables related to the procedure itself, like the amount of cement injected or the number of vertebrae treated, did not predict long-term outcomes. What mattered was the patient’s age and overall health going into the procedure.

Radiation Exposure During the Procedure

Because vertebroplasty requires continuous fluoroscopic guidance, radiation exposure is a concern primarily for the doctors performing the procedures rather than for patients, who typically undergo it once or twice. One study found that without special precautions, the operator’s hand dose averaged over 2 mSv per vertebra treated and the whole-body dose was about 1.4 mSv per vertebra. After implementing shielding techniques and radiation-reduction protocols, the same institution brought those figures down dramatically, to 0.07 mSv for the hand and 0.004 mSv for the whole body.²⁸ Using specialized cement injectors that allow the operator to stand farther from the X-ray beam also helps; one study found that a bone cement injector reduced hand radiation exposure by roughly two-thirds compared to manual injection with a syringe.²⁹ Even with these measures, an analysis of cumulative exposure for surgeons performing many procedures per year found that the annual risk of developing a thyroid cancer was very small and the risk of radiation-induced cataracts was low but not negligible.³⁰

Vertebroplasty for Spinal Metastases

Outside of osteoporotic fractures, vertebroplasty has found a role in treating vertebral fractures caused by cancer that has spread to the spine. These patients have a different goal: the procedure is palliative, aimed at reducing pain and stabilizing a weakened vertebra rather than curing the disease. A study of patients with osteolytic metastatic spinal tumors treated with vertebroplasty followed by radiation therapy found that nearly half achieved marked-to-complete pain relief within three days, and the average pain score dropped from about 8 out of 10 to 3 out of 10. No major complications were observed, and no further collapse of the treated vertebrae occurred during follow-up.³¹ A broader review confirmed that vertebroplasty appears effective as a palliative procedure for compression fractures from solid tumors and can be combined with radiation and chemotherapy.³²

The sham trial controversy does not apply here in the same way, because no one has performed sham-controlled vertebroplasty trials in cancer patients, and the ethical considerations of withholding treatment from cancer patients in severe pain make such trials unlikely. The clinical consensus for metastatic vertebral fractures is more straightforward: vertebroplasty is a useful tool in a broader palliative plan.

Predicting Who Will Respond

Before vertebroplasty, most patients get an MRI to look for bone marrow edema, which is a sign that the fracture is still actively healing and generating pain. The intuition is straightforward: if the fracture shows active inflammation, stabilizing it with cement should help. One study found that patients with extensive bone marrow edema on MRI had significantly better pain improvement after vertebroplasty compared to patients without edema, with pain scores dropping by about 4.6 points versus 2.7 points.³³ However, the relationship is not absolute. Another study found that while all patients with edema improved, some patients without edema on MRI also benefited, and the absence of edema did not reliably predict a poor outcome.³⁴

CT-based bone density measurements have emerged as a more reliable predictor of complications than of initial pain relief. Low bone density at the vertebral level next to the treated one, measured as Hounsfield units on CT, is a strong predictor of adjacent fractures after the procedure.³⁵ This means the same imaging that helps plan the procedure can also flag patients who need more aggressive osteoporosis treatment afterward to protect the rest of their spine.

Cost and Access

Vertebroplasty is generally less expensive than kyphoplasty and can be performed as an outpatient procedure in many cases. A U.S. cost-effectiveness analysis found that outpatient vertebroplasty cost roughly $12,000 per quality-adjusted life year gained compared to conservative medical management, well below standard thresholds for what the healthcare system considers worthwhile spending. Inpatient vertebroplasty was more expensive at around $40,000 per QALY gained but still within the accepted range.³⁶ A European study found that vertebroplasty was significantly more cost-effective than conservative treatment in the first week and at three months, though the advantage narrowed by twelve months as conservative treatment patients gradually improved.³⁷ The cost picture reinforces the clinical one: the strongest case for vertebroplasty is in patients with severe, acute pain who stand to benefit from rapid relief rather than waiting weeks or months for natural improvement.