Vertebroplasty/Kyphoplasty
- Both procedures inject bone cement (PMMA) into a fractured vertebral body to splint it from the inside and quiet the pain.
- The classic target is a painful osteoporotic compression fracture that won't settle with conservative care — not every wrinkly old vertebra you happen to see.
- The big difference: kyphoplasty inflates a balloon first to make a cavity (and maybe restore a little height); vertebroplasty just injects cement into the bone as-is.
- The headline risk is cement going where it shouldn't — leaking into the spinal canal, veins, or lungs.
- This is pain control, not a cure: it stabilizes the broken bone but doesn't fix the osteoporosis underneath.
Imagine a stale marshmallow that someone sat on — squished, sad, and aching every time you nudge it. That's an osteoporotic vertebral body that has fractured and collapsed under nothing more dramatic than gravity. Vertebroplasty and kyphoplasty are the radiologist's version of pouring quick-setting grout into that squished marshmallow so it stops grinding against itself with every breath, cough, and sneeze.
The "grout" is real: it's polymethylmethacrylate (PMMA), the same family of bone cement orthopedic surgeons use to seat hip implants. It goes in as a toothpaste-thick paste and hardens into a hard internal cast within minutes. The vertebra doesn't grow back — it just stops moving, and the micro-motion is a big part of why these fractures hurt so much.
Who actually needs this
The bread-and-butter patient has a painful osteoporotic compression fracture that has stubbornly refused to calm down with rest, pain medication, and time. The other major group is people with vertebrae weakened or eaten away by tumor — metastases or myeloma — where the bone is both painful and structurally unreliable.
Timing and patient selection are everything here. Most fresh osteoporotic fractures improve on their own over a few weeks, so the procedure is reserved for the ones that stay miserable. The pain should also match the fracture — point tenderness over that level, and ideally marrow edema on MRI confirming the fracture is fresh and "active" rather than an old, healed pancake.
A key piece of homework before you ever pick up a needle: prove the painful vertebra is the guilty one. An old, long-healed compression fracture is just scenery — cementing it does nothing. That's why we lean on MRI marrow edema (or a bone scan) to separate "this one hurts" from "this one happened during the Clinton administration."
Vertebroplasty vs. kyphoplasty
Both end with cement in the bone. The difference is what happens before the cement.
| Feature | Vertebroplasty | Kyphoplasty |
|---|---|---|
| Extra step | None — inject straight into bone | Inflate a balloon to make a cavity first |
| Cement delivery | Higher pressure into intact trabeculae | Lower pressure into a pre-made cavity |
| Height restoration | Minimal | May partially restore height / reduce kyphosis |
| Leak risk | Slightly higher (in theory) | Slightly lower (low-pressure fill) |
Think of vertebroplasty as injecting filler directly into a dense sponge — it has to push its way between the existing struts. Kyphoplasty first inflates a little balloon to carve out a clean pocket (and gently jack the endplates apart), then fills that tidy cavity at low pressure. The low-pressure fill is the main reason kyphoplasty was designed to leak less, though in practice both are workhorses and the choice often comes down to operator preference and fracture morphology.
How it goes down
The patient lies prone, lightly sedated — this is usually moderate sedation, not general anesthesia. Under fluoroscopy, a stout needle is driven through the pedicle — the bony bridge connecting the back of the vertebra to the body — into the collapsed vertebral body. The pedicle is the on-ramp because it keeps the needle safely lateral to the spinal canal.
Then comes the part that demands a steady hand and constant imaging: the cement goes in slowly, watched in real time as a dense white blush spreading through the bone. The whole game is to fill the marrow space while it's still inside the four walls of the vertebra — and to stop the instant it heads anywhere it shouldn't.
Where it goes wrong
The signature complication is cement extravasation — the paste escaping the vertebral body before it sets. Most leaks are tiny and silent, but the dangerous destinations are the ones to respect:
Cement that leaks posteriorly into the spinal canal can compress the cord or nerve roots — the scenario you lose sleep over. Cement that escapes into the basivertebral or paravertebral veins can travel as an embolus, and a small amount can even reach the lungs as a cement pulmonary embolism. This is exactly why every injection is done under live fluoroscopy and stopped at the first hint of cement straying outside the bone.
Other things to counsel about: a fracture of the vertebra next door (an adjacent-level fracture) can happen down the line, partly because the cemented level is now stiffer than its neighbors, and partly because the underlying osteoporosis is still there. Infection and bleeding are uncommon but real, as with any percutaneous procedure.
Cementing the bone treats the symptom, not the disease. The patient still walks out with brittle osteoporotic bone, so the procedure should always be paired with real osteoporosis management — because the next marshmallow is already lined up.
The takeaway
Vertebroplasty and kyphoplasty are elegant, targeted pain procedures: prove the right vertebra is to blame, thread a needle through the pedicle, and grout the broken bone back into one quiet piece — all while watching like a hawk to make sure the cement stays home.