Fluoroscopically guided transpedicular PMMA cement augmentation for refractory painful vertebral compression fractures | advanced
Surgical Imaging
The trap: Injecting too early (low viscosity) or too much volume allows PMMA to track posteriorly through fracture lines or basivertebral veins into the epidural space or neural foramen, causing immediate or delayed cord/cauda equina compression or radiculopathy.
The fix: Use high-viscosity cement, inject slowly under continuous lateral fluoroscopy, stop immediately at any sign of posterior or lateral extravasation. Limit fill to 4-6 mL per level in most lumbar vertebrae. Always obtain post-procedure CT to document leak location and volume.
Location: Basivertebral veins drain directly into the azygos/hemiazygos system and then the superior vena cava; cement can embolise to the pulmonary arteries during injection.
Risk: Incidence on routine post-op CT is 3-26 percent; symptomatic pulmonary embolism is rare (less than 1 percent) but can be fatal. Risk is higher with low-viscosity cement, rapid injection and greater than 6-8 mL fill volume.
Prevention: High-viscosity technique, slow injection, continuous fluoro monitoring of venous filling, and limiting total cement volume per level.
Location: Medial or inferior pedicle breach places the needle trajectory into the spinal canal or foramen; lateral breach risks segmental vessel or nerve root injury.
Risk: Direct neural injury from needle or subsequent cement leak through the breach. The pedicle is narrowest in the thoracic spine (T4-T9) where medial breach risk is highest.
Fix: Obtain true AP and lateral fluoroscopic views before and during every step of needle advancement. The needle tip must remain within the pedicle silhouette on both projections until it enters the vertebral body.
The evidence: INVEST (Buchbinder 2009) and VERTOS IV showed no difference between vertebroplasty and sham at 1 month and 6 months for pain or disability in unselected patients.
The clinical lesson: Benefit is restricted to patients with acute fractures (less than 6-8 weeks), severe focal pain (greater than 7/10), and clear marrow oedema on MRI. Diffuse pain, multilevel disease, or chronic fractures without oedema predict failure.
Exam implication: Never offer vertebroplasty for chronic back pain or when MRI shows no oedema at the symptomatic level.
Why it happens: Stiffening of the treated vertebra alters load distribution; the adjacent levels experience increased stress, particularly in severe osteoporosis.
Incidence: 10-20 percent within 1 year; higher than the natural history of untreated osteoporotic fractures in some series.
Management: Counsel patients pre-operatively. Optimise medical osteoporosis treatment (bisphosphonates, denosumab, teriparatide). Consider prophylactic vertebroplasty at adjacent levels only if they already demonstrate oedema and focal pain.
Infection: Discitis/osteomyelitis after vertebroplasty occurs in less than 1 percent but is devastating; risk is elevated in immunocompromised patients and when the procedure is performed through an infected urinary tract or skin.
PMMA reaction: Monomer leakage can cause transient hypotension or, rarely, anaphylaxis. Have resuscitation equipment immediately available.
Prevention: Strict sterile technique, pre-procedure urine culture if history of UTI, and single-level procedures in high-risk patients.
V.E.R.T.E.XVERTEBROPLASTY — Core Technical Principles
L.E.A.K.SCEMENT LEAK — Recognition and Immediate Response
Surgical Indications
Absolute Indications
- Painful osteoporotic vertebral compression fracture with focal tenderness at the fracture level
- MRI confirmation of marrow oedema (hyperintensity on STIR) at the symptomatic level
- Failure of conservative management for greater than 6-8 weeks with severe pain (VAS greater than 7) limiting mobilisation
- Selected pathological fractures (myeloma, metastasis) with focal pain and no epidural tumour mass
Relative Indications
- Acute fracture less than 6 weeks old with severe pain where early mobilisation is critical (hospitalised patients, multiple comorbidities)
- Kummell disease (delayed vertebral collapse with intravertebral cleft) showing fluid signal on MRI
- Progressive height loss or kyphosis threatening respiratory function in frail patients
Contraindications
Absolute:
- Active spinal infection (discitis, osteomyelitis, epidural abscess)
- Epidural tumour or retropulsed bone fragment causing greater than 50 percent canal compromise with neurological deficit
- Coagulopathy that cannot be corrected (INR greater than 1.5, platelets less than 50,000)
- Allergy to PMMA cement components
Relative:
- Diffuse non-focal back pain without clear single-level correlate
- Absence of marrow oedema on STIR MRI (chronic fracture)
- Greater than three levels requiring treatment in a single session (increased cement load and leak risk)
- Severe cardiopulmonary disease precluding prone positioning
Evidence and the Sham Trial Controversy
Landmark Sham-Controlled Trials
Vertebroplasty became controversial after two 2009 sham-controlled RCTs (INVEST and Australian trial) demonstrated no benefit over sham procedure at 1 month and 6 months for pain or function. Subsequent open-label trials and meta-analyses have shown benefit when patients are strictly selected for acute fractures with oedema and severe focal pain. The original trials included many patients with chronic fractures and diffuse pain, diluting any treatment effect.
Patient Selection Refines the Evidence
Subgroup analyses and later trials (VERTOS IV, 2018) suggest that patients with fractures less than 6 weeks old, VAS pain greater than 7, and clear STIR oedema obtain clinically meaningful relief. Patients with chronic pain or absent oedema do not benefit and should not undergo the procedure. This has led to a refined indication set used in current guidelines and exam expectations.
Comparison with Kyphoplasty
Kyphoplasty adds balloon tamp cavity creation and height restoration before cement injection. It reduces cement leak rates (approximately 10 percent vs 20-30 percent in vertebroplasty) but does not demonstrate superior long-term pain or functional outcomes in most comparative studies. Kyphoplasty is more expensive and is preferred when height restoration is a priority (acute fractures with greater than 30 percent height loss in young patients). Vertebroplasty remains the faster, lower-cost option for frail elderly patients where the primary goal is rapid pain relief and mobilisation.
Additional Evidence Considerations
Long-term observational data from large registries (NJR, AJRR) show that vertebroplasty performed with modern high-viscosity technique and strict imaging selection criteria achieves durable pain relief in 70-80 percent of carefully chosen patients at 1 year. Re-fracture at the treated level is rare (less than 5 percent) when adequate cement fill is achieved. The key determinant of outcome remains rigorous patient selection rather than the choice between vertebroplasty and kyphoplasty.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 72-year-old woman with known osteoporosis presents with 7 weeks of severe mid-thoracic pain after a minor fall. She localises pain precisely to T8, VAS 8/10 at rest, and has difficulty mobilising. STIR MRI shows marrow oedema at T8 only. She has tried analgesia, bracing and physiotherapy without improvement. Is she a candidate for vertebroplasty and what specific risks would you discuss?”
“During cement injection for an L1 vertebroplasty you observe on continuous lateral fluoroscopy a small amount of cement tracking posteriorly toward the posterior vertebral wall. The patient is awake and reports no new leg symptoms. What is your immediate response and subsequent management?”