Vertebroplasty and Kyphoplasty

Vertebroplasty and kyphoplasty are minimally invasive procedures that inject bone cement, typically PMMA (polymethylmethacrylate), percutaneously into a vertebral compression fracture (VCF) to relieve pain and stabilise it mechanically. Vertebroplasty injects the cement alone; kyphoplasty first expands a balloon in the vertebral body and may restore some height. Both were popular before landmark sham-controlled trials called their efficacy into question.

History. Galibert first performed vertebroplasty in France in 1987, for a painful cervical haemangioma. Kyphoplasty followed in the 1990s, adding a balloon to create a cavity and potentially restore vertebral height. Adoption was rapid, and it came before rigorous evidence existed.

The controversy. The evidence splits cleanly along trial design, and that is the single most examined point in this topic. Open-label trials comparing augmentation with conservative care were positive, showing superior early pain and function; double-blind sham-controlled trials found no benefit over a sham injection, even in acute fractures. The one dissenting sham-controlled trial, VAPOUR, enrolled only very acute (under 6-week), severely painful fractures, used an "adequate vertebral fill" technique, and was positive.

Where practice stands. The 2018 Cochrane review concluded there is no important benefit over sham. Practice has consequently shifted toward conservative management first, rigorous selection and shared decision-making. The individual trials are set out under Outcomes.

The anatomy that matters. The target is the vertebral body, the anterior column, and the needle reaches it through the pedicle. Behind the body lie its posterior wall and then the spinal canal with the neural structures. The basivertebral venous plexus is the pathway along which cement leaks.

The fracture. Axial loading on osteoporotic bone fails the anterior column, and the vertebra wedges anteriorly; the posterior wall and pedicles are usually spared. The pain comes from the periosteal nerves, from instability and from the inflammatory response. The thoracolumbar junction (T11-L2) is the most common level.

Osteoporosis is the primary risk factor. The others:

• Corticosteroid use
• Metastatic disease
• Multiple myeloma
• Primary bone tumours

The cement. PMMA provides immediate stability, but it has no biological incorporation and remains a foreign body. It polymerises exothermically, generating heat, and its viscosity changes during injection.

Height restoration. In kyphoplasty the balloon creates a cavity in the cancellous bone and may restore some vertebral height. Kyphosis correction is usually modest, and height restoration may not correlate with clinical outcome.

Fractures are graded by how much height they have lost and grouped by cause; the procedures are grouped by approach and by how the cavity, if any, is made.

Who is a candidate. A painful osteoporotic VCF that has failed 3-6 weeks of conservative treatment, in a patient in whom:

• MRI shows bone marrow oedema, confirming the fracture is acute
• The pain localises to the fracture level
• There is no neurological deficit
• The posterior wall is intact on imaging

History. The mechanism is typically minimal trauma in an osteoporotic fracture. Establish how long the symptoms have lasted, the character and location of the pain, and the functional limitation, and ask about the red flags for malignancy or infection.

Examination. Look for midline tenderness over the fracture level and for tenderness elsewhere in the spine that may mean more than one level. Examine the neurology to rule out a deficit, and assess sagittal alignment for kyphosis.

Contraindications. A neurological deficit needs decompression, not cement, and heads the absolute list.

Absolute

• Neurological deficit requiring decompression
• Active infection, vertebral or systemic (osteomyelitis, discitis)
• Uncorrectable coagulopathy
• Severe posterior wall destruction or burst fracture with canal compromise

Relative

• Healed fracture, with no oedema on MRI
• Minimal symptoms (consider other sources of the pain)
• Retropulsion of fragments
• More than 3 levels requiring treatment
• Young patient (consider other options)

Differential diagnosis. Before augmenting, the surgeon must be certain the fracture is benign and osteoporotic, not a sinister mimic. Augmenting a malignant or infected vertebra without a tissue diagnosis is a classic exam trap.

Radiographs. AP and lateral views of the affected region document the height loss and show alignment and kyphosis. They cannot determine whether the fracture is acute, cannot assess the soft tissues and may miss subtle fractures, so they serve for initial screening and follow-up but are not sufficient for planning augmentation.

MRI is the gold standard for fracture acuity and for ruling out other pathology, and it is essential to patient selection. The acute fracture is T1 hypointense and T2/STIR hyperintense, and it is the bone marrow oedema on STIR that confirms acuity. Oedema typically persists 3-6 months; a fracture without it is chronic or healed and unlikely to benefit from cement. The same scan assesses the integrity of the posterior wall, rules out infection (endplate changes, a paravertebral collection) and evaluates for malignancy.

CT gives superior bony detail for planning. It defines the posterior wall integrity, which is critical, along with the fracture morphology and any canal compromise, and it plans the needle trajectory and evaluates cement from any previous procedure. It is essential when posterior wall involvement is suspected, when planning for a burst-type pattern, and for evaluating bone quality.

Other tests.

• DEXA confirms osteoporosis, gives a baseline for monitoring treatment, and its T-score guides systemic treatment
• Laboratory tests: SPEP, UPEP and light chains to rule out myeloma; inflammatory markers if infection is suspected; coagulation studies before the procedure
• Bone scan: the alternative if MRI is contraindicated. Increased uptake means an active fracture, but it is less specific than MRI

Most VCFs improve with conservative care, and augmentation is reserved for the fracture that does not. The pathway runs:

1. Diagnose and assess. Confirm a painful VCF on history and examination, image with an X-ray and then MRI to assess acuity and rule out tumour or infection, and assess for a neurological deficit and posterior wall involvement.
2. Rule out contraindications. A neurological deficit means considering surgery, and a burst fracture with canal compromise means surgery. Active infection is treated, and coagulopathy is corrected before any procedure.
3. Conservative treatment for 3-6 weeks. Most patients improve.
4. Persistent severe pain. Confirm the MRI oedema is still present (an acute fracture), discuss the evidence and the VERTOS controversy with the patient, and make the decision together. Because the trial evidence is mixed, that shared decision includes the risks of cement leak and embolism.
5. If augmentation is chosen. Vertebroplasty or kyphoplasty (outcomes are similar), informed consent that includes the risks of extravasation, a transpedicular approach under fluoroscopic guidance, and continued osteoporosis management after the procedure.

Algorithm

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Conservative care. Analgesia (paracetamol, NSAIDs, opioids if needed), activity modification, physiotherapy as tolerated and osteoporosis treatment. Bracing is controversial and its evidence limited. The trial typically runs 3-6 weeks before intervention is considered, though persistent severe pain may prompt earlier intervention.

Treat the osteoporosis. Whatever is decided about cement, the systemic treatment is essential:

• Calcium and vitamin D supplementation
• Bisphosphonates or denosumab
• Anabolic agents (teriparatide) considered for severe cases
• Fall prevention and lifestyle modification

Vertebroplasty or kyphoplasty. The choice depends on the fracture characteristics and the desired outcome.

When to operate instead. Open surgery is indicated for neurological compromise or instability:

• Neurological deficit
• Significant canal compromise
• Unstable burst fracture
• Progressive kyphosis requiring correction
• Infection (debridement needed)
• Tumour requiring resection

Both procedures are done under local anaesthesia with sedation, or general anaesthesia, with the patient prone and biplanar fluoroscopy (AP and lateral).

VertebroplastyKyphoplasty

Needle placement.

1. Local anaesthetic to the skin and periosteum
2. An 11-13G trocar needle through the pedicle (transpedicular)
3. Advance to the anterior third of the vertebral body
4. AP view: the needle should not cross the medial pedicle wall until it is in the body
5. Lateral view: the tip in the anterior third of the body

Cement injection.

1. Mix the PMMA to an appropriate viscosity
2. Inject slowly under continuous fluoroscopy
3. Watch for extravasation (epidural, disc, venous)
4. Stop if cement approaches the posterior wall
5. Fill typically 2-5 mL per level

One pedicle or two. A unipedicular approach uses a single needle and may not fill the contralateral side. A bipedicular approach uses two needles and fills better, at the cost of a longer procedure.

The set-up, positioning and transpedicular needle placement are the same as for vertebroplasty. Then:

1. Place a working cannula through the pedicle
2. Insert the balloon tamp into the vertebral body
3. Inflate the balloon with radiopaque contrast, monitoring pressure and volume; it creates a cavity and may restore height
4. Deflate and remove the balloon
5. Inject cement into the cavity, monitored with fluoroscopy

Why the cavity helps. It gives the cement a controlled space, which fills at lower pressure with less extravasation. A potentially lower extravasation rate, possible height restoration and controlled cement placement are the advantages that make kyphoplasty the preferred technique when height restoration is desired.

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Cement. A "toothpaste" consistency is preferred. Too thin and it risks extravasation; too thick and it is difficult to inject. Avoid overfilling: quality of fill matters more than quantity.

Fluoroscopy. Monitor continuously throughout the injection, with the lateral view watching the posterior wall and the AP view the midline and pedicle. Continuous screening is the key: it detects extravasation the moment it starts.

Cement leakage is the most common complication. On direct comparison vertebroplasty leaks more often than kyphoplasty, at about 39% of levels against 29% (Rose 2024). Leaks usually go into the disc, the epidural space or the paravertebral veins and are almost always asymptomatic; they become symptomatic only through neural compression or pulmonary cement embolism. High-viscosity cement and continuous fluoroscopy reduce the risk.

New neurological symptoms after augmentation require urgent imaging and spine-surgical assessment rather than observation. Radiographs after kyphoplasty may miss an epidural cement leak.

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Pulmonary cement embolism. Cement migrates through the paravertebral and basivertebral venous system to the lungs. Reported incidence varies widely, from about 2% to 26% (systematic review, Wang 2012); most emboli are asymptomatic and detected incidentally, and rarely they cause cardiopulmonary compromise or death.

• Prevention: high-viscosity cement, slow injection, and stop immediately if venous filling is seen on fluoroscopy
• Treatment: supportive; anticoagulation for symptomatic peripheral emboli; surgical retrieval only for large central emboli

New and adjacent fractures. Across the randomised trials, new symptomatic vertebral fractures occur at broadly similar rates after vertebroplasty and after control, and the Cochrane 2018 review found no clear increase attributable to cement. Whether cement increases the adjacent-level risk remains genuinely contested.

• Some argue cement stiffening increases the adjacent-segment risk
• Cement leaking into the disc space may increase stress at the adjacent levels, potentially contributing to adjacent-level fractures
• Others argue new fractures simply reflect the underlying osteoporotic progression, and both augmented and non-augmented patients sustain them
• They likely reflect the osteoporotic progression as much as the procedure
• Risk factors: osteoporosis severity, cement volume, residual kyphosis

Other complications. Infection (rare, less than 1%), pedicle fracture, rib fracture at thoracic levels, haematoma and transient radiculopathy. Thermal injury from the exothermic reaction is rare.

Recovery. Monitor for 2-4 hours, with neurological and pain assessment, and mobilise when comfortable. Discharge is typically the same day or the next, with a return to normal activities as tolerated and analgesia as needed, often reduced. Follow-up is a clinical assessment at 4-6 weeks, with radiographs if new symptoms appear, and DEXA per the osteoporosis guidelines.

The negative sham-controlled trials. Three double-blind sham-controlled RCTs found no benefit:

• Kallmes / INVEST (NEJM 2009), 131 patients: no significant difference in RDQ disability or pain at 1 month, with high crossover from control to vertebroplasty by 3 months (51% vs 13%)
• Buchbinder (NEJM 2009), 78 patients in Australia with MRI-confirmed unhealed fractures less than 12 months old: no benefit over sham at 1 week or at 1, 3 or 6 months
• VERTOS IV / Firanescu (BMJ 2018), 180 patients with acute fractures: no significant difference in VAS pain across 12 months, extending the negative sham finding to acute fractures

The positive open-label trials. Both compared augmentation with conservative care without a sham arm, and the open-label design limits interpretation.

• VERTOS II / Klazen (Lancet 2010), 202 patients with acute fractures (MRI oedema, under 6 weeks): greater pain relief with vertebroplasty at 1 month and 1 year
• FREE / Wardlaw (Lancet 2009), 300 patients, balloon kyphoplasty against non-surgical care: SF-36 PCS improved 7.2 vs 2.0 points at 1 month (difference 5.2), the benefit diminishing by 12 months

The dissenting sham trial. VAPOUR / Clark (Lancet 2016) was a double-blind, placebo-controlled RCT of 120 patients with acute fractures (under 6 weeks) and NRS pain of at least 7/10. 44% vs 21% achieved NRS pain below 4/10 at 14 days, a between-group difference of 23 percentage points, which suggests that acuity and vertebral fill matter.

Reading the split. Patient selection, fracture age and vertebral-fill technique are all disputed between the trials.

Against augmentation. The sham-controlled trials show no benefit, the placebo effect is likely significant, and the complications from cement are real.

For selective use. Acute fractures (under 6-8 weeks) may benefit, and pain relief is rapid, even if it diminishes over time. VAPOUR and other trials suggest early intervention helps, and patient selection may be key.

Global Epidemiology

Osteoporotic vertebral compression fracture is the most common fragility fracture worldwide, and its burden is rising with population ageing - the over-65 population is the fastest-growing demographic globally, driving a parallel rise in age-related spinal disorders including osteoporotic compression fractures. The thoracolumbar junction (T11-L2) is the predominant level because it is the mechanical transition between the rigid thoracic and mobile lumbar spine. Most fractures are low-energy in women over 60 with established osteoporosis; only a minority are clinically recognised, as many are detected incidentally on imaging.

Major Guidance, Side by Side

The practical exam point is that the disagreement is real and design-driven: bodies weighting the double-blind sham-controlled trials (Cochrane, NICE) are restrictive, while those weighting open-label and the positive VAPOUR sham trial are more permissive.

Registry and Outcome Evidence

There is no dedicated international vertebral-augmentation joint registry analogous to the arthroplasty registries (NJR, AJRR, AOANJRR). Evidence therefore comes from RCTs and large administrative cohorts, which is part of why the controversy persists. Across the randomised literature, new symptomatic vertebral fractures after vertebroplasty occur at broadly similar rates to controls (Cochrane 2018: no clear increase), arguing against the older fear that cement reliably causes adjacent-level fracture.

Global Practice Variation

Pathological (neoplastic) fractures. The intent is palliative: pain relief and quality of life. Cement may provide stability for radiation therapy and is considered in conjunction with radiation or systemic therapy, but the extravasation risk may be higher where tumour has destroyed the bone. Consider surgery instead for a neurological deficit or significant canal compromise, where a tissue diagnosis is needed, or where life expectancy warrants more definitive treatment.

Multiple levels. Each level adds procedural time and risk, and the cement load is cumulative. Prioritise the most symptomatic levels and consider staged procedures.

Timing. Acuity is judged on the MRI oedema:

• Acute (under 6 weeks): VAPOUR suggests possible benefit, and augmentation may offer faster pain relief
• Subacute (6 weeks to 3 months): benefit debatable and conservative treatment often effective; consider for severe refractory pain
• Chronic (more than 3 months): little evidence of benefit, and a healed fracture is unlikely to respond to cement

Young patients. Avoid augmentation if possible and reserve it for exceptional circumstances. Traumatic VCF in young patients is usually treated surgically, an underlying bone pathology should be considered, and the long-term effects of cement are unknown.

Key Takeaways

1. Design-Driven Controversy: Double-blind sham-controlled trials (Kallmes/INVEST and Buchbinder, NEJM 2009; VERTOS IV, BMJ 2018) found no benefit over sham, while open-label trials (VERTOS II Lancet 2010, FREE Lancet 2009) were positive. Do not confuse VERTOS II (open-label, positive) with the negative NEJM trials - this is the commonest exam trap.

2. Acute Fractures May Differ: The VAPOUR sham-controlled trial (Lancet 2016) showed benefit for very acute fractures (under 6 weeks). Timing may matter - MRI oedema confirms acuity.

3. Cement Leakage is Common: Leakage occurs in about 39% of vertebroplasty and 29% of kyphoplasty levels, mostly asymptomatic. Serious complications (epidural compression, pulmonary cement embolism) are rare but can occur.

4. Contraindications are Critical: Neurological deficit requires decompression, not cement. Healed fractures without edema will not benefit.

5. Kyphoplasty vs Vertebroplasty: Kyphoplasty creates a cavity (lower extravasation, may restore height) but clinical outcomes are similar. Height restoration does not clearly correlate with pain relief.

6. Treat the Osteoporosis: Systemic osteoporosis management is more important than the augmentation procedure. All patients need calcium, vitamin D, and anti-resorptive therapy.

7. Shared Decision-Making: Given the controversial evidence, honest discussion with patients about the limited evidence is essential. Conservative treatment remains a reasonable alternative.