Vertebroplasty and Kyphoplasty for Spinal Fractures
Vertebroplasty and kyphoplasty are minimally invasive interventional radiology procedures designed to stabilize vertebral compression fractures, most commonly caused by osteoporosis, metastatic cancer, or traumatic injury. Both techniques involve the image-guided delivery of bone cement into a fractured vertebral body, with the goal of reducing pain and restoring structural integrity. Understanding the distinctions between these two procedures — and the clinical conditions that favor one over the other — is central to how interventional radiologists evaluate spinal fracture cases.
Definition and Scope
Vertebral compression fractures (VCFs) represent the most common osteoporotic fractures in the United States, with the American Academy of Orthopaedic Surgeons citing approximately 700,000 VCFs occurring annually in the US. These fractures cause the anterior column of the vertebral body to collapse, producing pain, height loss, and progressive kyphotic deformity. Conservative management — rest, analgesics, bracing — fails to resolve pain in a substantial subset of patients, establishing the clinical need for procedural intervention.
Vertebroplasty is defined by the direct percutaneous injection of polymethylmethacrylate (PMMA) cement into the fractured vertebral body under fluoroscopic or CT guidance, without prior cavity creation. The procedure stabilizes the fracture through mechanical reinforcement.
Kyphoplasty (balloon kyphoplasty) introduces an additional step: an inflatable bone tamp (balloon) is inserted and expanded within the vertebral body before cement injection. Balloon inflation creates a cavity, which may partially restore vertebral height and reduce kyphotic angulation before cement fills the space. The Society of Interventional Radiology (SIR) classifies both procedures under image-guided spine interventions within its clinical practice guidelines.
The regulatory context for radiology governing these procedures in the US involves FDA oversight of PMMA bone cements as Class II or Class III devices, depending on formulation and cleared indication, as well as CMS coverage determinations under Medicare that define reimbursable clinical criteria.
How It Works
Both procedures follow a structured sequence performed under fluoroscopic or CT image guidance, typically with the patient prone under local anesthesia and conscious sedation.
Vertebroplasty — procedural sequence:
- Access: A beveled trocar needle is advanced transpedicularly (through the pedicle of the vertebra) or parapedicularly into the fractured vertebral body under real-time fluoroscopy.
- Confirmation: Contrast venography may be performed to evaluate vascular communication and reduce cement embolism risk.
- Cement injection: Low-viscosity PMMA cement is injected in small increments (typically 2–8 mL per level) under continuous fluoroscopic monitoring.
- Solidification: Cement polymerizes within 10–15 minutes, providing immediate mechanical stabilization.
Kyphoplasty — additional steps between access and cement injection:
- An inflatable bone tamp is inserted through a working cannula into the vertebral body.
- The balloon is inflated under pressure (up to 220 psi in some systems) to create an intravertebral cavity and compact the surrounding cancellous bone.
- The balloon is deflated and removed; the pre-formed cavity is then filled with higher-viscosity cement under lower injection pressure.
The higher viscosity of cement used in kyphoplasty and the lower injection pressure are intended to reduce the rate of cement leakage compared to vertebroplasty, though both techniques carry a leakage risk that image guidance is specifically designed to detect and manage.
Common Scenarios
The three principal clinical settings where vertebroplasty or kyphoplasty is considered are:
- Osteoporotic vertebral compression fractures: The most frequent indication. Fractures with persistent pain unresponsive to 4–6 weeks of conservative treatment, confirmed by MRI edema signal indicating acuity, are the prototypical case.
- Malignant VCFs: Metastatic lesions (from breast, lung, prostate, renal cell, or multiple myeloma) that destroy trabecular bone, causing painful pathologic fractures. The American College of Radiology (ACR) Appropriateness Criteria address this indication, weighing tumor type, patient prognosis, and spinal stability. Radiation therapy planning may accompany or precede the procedure.
- Traumatic fractures in younger patients: Less common, but considered in select cases of acute burst fractures or Kümmell's disease (post-traumatic avascular necrosis of the vertebra) without posterior element involvement or neurologic compromise.
The thoracic and lumbar spine (T4–L5) accounts for the large majority of treated levels; the cervical spine is rarely approached with these techniques due to anatomic constraints.
Decision Boundaries
Choosing between vertebroplasty and kyphoplasty — or neither — depends on fracture characteristics, clinical goals, and risk profile.
Vertebroplasty vs. Kyphoplasty — key distinctions:
| Feature | Vertebroplasty | Kyphoplasty |
|---|---|---|
| Cavity creation | No | Yes (balloon tamp) |
| Height restoration potential | Minimal | Moderate (variable) |
| Cement viscosity | Lower | Higher |
| Procedure time | Shorter | Longer |
| Equipment cost | Lower | Higher |
| Cement leakage rate | Higher in published series | Reduced in controlled studies |
Contraindications recognized in ACR and SIR guidance include: active osteomyelitis at the target level, uncorrectable coagulopathy, fractures with posterior cortex disruption that communicates with the spinal canal, and neurologic deficit directly attributable to bony retropulsion (where surgical decompression is the appropriate pathway).
Imaging prerequisites are mandatory. MRI with STIR or fat-suppressed sequences identifies edema-positive (acute or subacute) fractures amenable to treatment. CT characterizes posterior wall integrity and pedicle anatomy. The ACR Appropriateness Criteria for vertebral augmentation provide evidence-ranked imaging and procedural guidance.
The broader landscape of image-guided spinal and musculoskeletal interventions is catalogued across the radiology resource index, including procedures such as radiofrequency ablation for metastatic bone lesions that may be performed in combination with vertebral augmentation.
References
- American College of Radiology — ACR Appropriateness Criteria
- Society of Interventional Radiology — Clinical Practice Guidelines
- American Academy of Orthopaedic Surgeons — Vertebral Compression Fractures
- U.S. Food and Drug Administration — Orthopedic Devices (PMMA Bone Cements)
- Centers for Medicare & Medicaid Services — Coverage Policies
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