Vertebroplasty and Kyphoplasty

Vertebroplasty and kyphoplasty are minimally invasive procedures involving percutaneous injection of bone cement (typically PMMA) into vertebral compression fractures to provide pain relief and mechanical stabilization. While initially popular, landmark sham-controlled trials have called their efficacy into question.

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Historical Development

Vertebroplasty was first performed by Galibert in France in 1987 for a painful cervical hemangioma. Kyphoplasty was developed in the 1990s with the addition of a balloon to create a cavity and potentially restore vertebral height. Rapid adoption occurred before rigorous evidence existed.

Current Controversy

The evidence splits cleanly along trial design, which is the single most examined point in this topic. Open-label trials comparing augmentation with conservative care were positive - VERTOS II (Klazen, Lancet 2010) and the FREE kyphoplasty trial (Wardlaw, Lancet 2009) both showed superior early pain and function. Double-blind sham-controlled trials were negative - two landmark trials published back-to-back in NEJM in 2009 (Kallmes/INVEST and Buchbinder) found no benefit over a sham injection, and VERTOS IV (BMJ 2018) confirmed this even in acute fractures. The one dissenting sham-controlled trial, VAPOUR (Lancet 2016), enrolled only very acute (under 6-week), severely painful fractures and used an "adequate vertebral fill" technique - and was positive. 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.

Vertebral Anatomy

Relevant Structures:

• Vertebral body (anterior column)
• Posterior wall of vertebral body
• Pedicle (needle pathway)
• Basivertebral venous plexus (cement leakage pathway)
• Spinal canal and neural structures posteriorly

Vertebral Compression Fracture Pathophysiology

Mechanism:

• Axial loading on osteoporotic bone
• Anterior column failure (anterior wedging)
• Usually spares posterior wall and pedicles
• Pain from periosteal nerves, instability, inflammatory response

Risk Factors for VCF:

• Osteoporosis (primary)
• Corticosteroid use
• Metastatic disease
• Multiple myeloma
• Primary bone tumors

Cement Biomechanics

PMMA Properties:

• Exothermic polymerization (heat generation)
• Viscosity changes during injection
• Provides immediate stability
• No biological incorporation (remains foreign body)

Height Restoration (Kyphoplasty):

• Balloon creates cavity in cancellous bone
• May restore some vertebral height
• Height restoration may not correlate with clinical outcome
• Kyphosis correction usually modest

Patient Selection

Clinical Assessment

History:

• Mechanism (minimal trauma typical for osteoporotic)
• Duration of symptoms
• Pain character and location
• Functional limitation
• Red flags for malignancy or infection

Physical Examination:

• Midline tenderness over fracture level
• Neurological examination (rule out deficit)
• Sagittal alignment (kyphosis assessment)
• Other spinal tenderness (multiple levels?)

Contraindications

Absolute:

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

Relative:

• Healed fracture with no edema
• Minimal symptoms
• Retropulsion of fragments
• More than 3 levels requiring treatment
• Young patient (consider other options)

Differential Diagnosis of a Vertebral Compression Fracture

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

Additional Investigations

Bone Density (DEXA):

• Confirms osteoporosis
• Baseline for treatment monitoring
• T-score guides systemic treatment

Laboratory:

• Rule out myeloma (SPEP, UPEP, light chains)
• Inflammatory markers if infection suspected
• Coagulation studies before procedure

Nuclear Medicine (Bone Scan):

• Alternative if MRI contraindicated
• Increased uptake = active fracture
• Less specific than MRI

Technical Pearls

Cement Viscosity:

• "Toothpaste" consistency preferred
• Too thin = extravasation risk
• Too thick = difficult injection

Fluoroscopy:

• Continuous monitoring during injection
• Lateral view for posterior wall
• AP view for midline and pedicle

Volume:

• Typically 2-5 mL per vertebra
• Avoid overfilling
• Quality over quantity

Postoperative Care

Same Day or Next Day Discharge:

• Mobilize when comfortable
• Analgesia as needed
• Resume activities as tolerated
• Follow-up in 4-6 weeks

Cement Extravasation

Other Complications

Pulmonary Cement Embolism:

• Reported incidence varies widely, from about 2% to 26% (systematic review, Wang 2012); most are asymptomatic and detected incidentally
• Cement migrates through the paravertebral and basivertebral venous system to the lungs
• May be asymptomatic or, rarely, cause cardiopulmonary compromise or death
• Prevention: high-viscosity cement, slow injection, stop immediately if venous filling is seen on fluoroscopy
• Treatment: supportive; anticoagulation for symptomatic peripheral emboli; surgical retrieval only for large central emboli

Adjacent / New Symptomatic Vertebral Fracture:

• Across randomised trials, new symptomatic fractures occur at broadly similar rates after vertebroplasty and control (Cochrane 2018 found no clear increase)
• Whether cement increases adjacent-level risk remains genuinely contested
• Likely reflects underlying 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 (thoracic levels)
• Hematoma
• Transient radiculopathy

Immediate Postprocedure

Recovery:

• Monitor for 2-4 hours
• Neurological assessment
• Pain assessment
• Mobilize when comfortable

Discharge:

• Same day or next day typical
• Return to normal activities as tolerated
• Analgesia as needed (often reduced)

Activity Guidelines

Osteoporosis Management - Critical

Essential Systemic Treatment:

• Calcium and Vitamin D supplementation
• Bisphosphonates or denosumab
• Consider anabolic agents (teriparatide) for severe cases
• Fall prevention strategies
• Lifestyle modifications

Follow-up:

• 4-6 weeks: Clinical assessment
• DEXA: Per osteoporosis guidelines
• Radiographs if new symptoms

Evidence Summary - The Controversy

Kallmes / INVEST (NEJM 2009):

• Double-blind, sham-controlled RCT, 131 patients
• No significant difference in RDQ disability or pain at 1 month
• High crossover from control to vertebroplasty by 3 months (51% vs 13%)

Buchbinder (NEJM 2009):

• Double-blind, sham-controlled RCT, 78 patients (Australia)
• 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):

• Double-blind sham-controlled RCT, 180 patients with acute fractures
• No significant difference in VAS pain across 12 months
• Extends the negative sham finding to acute fractures

VERTOS II / Klazen (Lancet 2010):

• Open-label RCT, vertebroplasty vs conservative care, 202 patients (acute, MRI oedema, under 6 weeks)
• Greater pain relief with vertebroplasty at 1 month and 1 year
• Open-label design (no sham) limits interpretation

VAPOUR Trial / Clark (Lancet 2016):

• Double-blind, placebo-controlled RCT, 120 patients, acute (under 6 weeks), NRS pain at least 7/10
• 44% vs 21% achieved NRS pain below 4/10 at 14 days (between-group difference 23 percentage points)
• The dissenting positive sham-controlled trial - suggests acuity and vertebral fill matter

FREE Trial / Wardlaw (Lancet 2009):

• Balloon kyphoplasty vs non-surgical care, 300 patients (open-label)
• SF-36 PCS improved 7.2 vs 2.0 points at 1 month (difference 5.2)
• Benefit diminished by 12 months; not sham-controlled

Interpretation

Arguments Against Augmentation:

• Sham-controlled trials show no benefit
• Placebo effect likely significant
• Complications from cement are real

Arguments For Selective Use:

• Acute fractures (under 6-8 weeks) may benefit
• Rapid pain relief (even if diminishes over time)
• VAPOUR and other trials suggest early intervention helps
• Patient selection may be key

Adjacent / New Vertebral Fractures

Incidence: across the randomised trials, new symptomatic vertebral fractures occur at broadly similar rates after vertebroplasty and control; the Cochrane 2018 review found no clear increase attributable to cement.

Debate:

• Some argue cement stiffening increases adjacent-segment risk
• Others argue it simply reflects underlying osteoporotic progression
• Both augmented and non-augmented VCF patients sustain new fractures

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) VCF

Different Considerations:

• Palliative intent (pain relief, quality of life)
• May provide stability for radiation therapy
• Cement extravasation risk may be higher (tumor destruction)
• Consider in conjunction with radiation/systemic therapy

When to Consider Surgery Instead:

• Neurological deficit
• Significant canal compromise
• Need for tissue diagnosis
• Life expectancy warrants more definitive treatment

Multiple Level Fractures

Challenges:

• Each level adds procedural time and risk
• Cumulative cement load
• Prioritize most symptomatic levels
• Consider staged procedures

Timing Considerations

Acute (under 6 weeks):

• VAPOUR trial suggests possible benefit
• May offer faster pain relief
• Edema on MRI confirms acuity

Subacute (6 weeks to 3 months):

• Debatable benefit
• Conservative treatment often effective
• Consider if severe refractory pain

Chronic (more than 3 months):

• Little evidence for benefit
• No edema on MRI = healed
• Unlikely to respond to cement

Young Patients

Avoid if Possible:

• Traumatic VCF in young patients usually treated surgically
• Consider underlying bone pathology
• Long-term effects of cement unknown
• Reserve for exceptional circumstances

Sacroplasty - The Sacral Analogue

Management Pathway

Step 1: Diagnosis and Assessment

• Confirm painful VCF (history, examination)
• Imaging: X-ray then MRI (assess acuity, rule out tumor/infection)
• Assess for neurological deficit, posterior wall involvement

Step 2: Rule Out Contraindications

• Neurological deficit → Consider surgery
• Active infection → Treat infection
• Burst fracture with canal compromise → Surgery
• Coagulopathy → Correct before procedure

Step 3: Conservative Treatment (3-6 weeks)

• Analgesia, activity modification
• Osteoporosis treatment (essential)
• Physical therapy as tolerated
• Most patients improve

Step 4: Persistent Severe Pain

• Confirm MRI edema still present (acute fracture)
• Discuss evidence with patient (VERTOS controversy)
• Shared decision-making

Step 5: If Augmentation Chosen

• Vertebroplasty vs kyphoplasty (similar outcomes)
• Informed consent including extravasation risks
• Transpedicular approach, fluoroscopic guidance
• Continue osteoporosis management post-procedure

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.