Fluoroscopically Visible Vertebral Fracture Instability Observed During Percutaneous Vertebroplasty

John D. Barr, MD
Michelle S. Barr, MD (Cleveland, OH)
Thomas J. Lemley, MMS, MPAS, PA–C
Richard M. McCann, RT(R)(CV) (Hershey, PA)

Introduction:

The mechanism of pain relief for fractures treated by vertebroplasty remains uncertain. Observations in two patients may provide an explanation.

Methods:

Fluoroscopically visible instability of vertebral fractures was observed in two patients, a 71 year–old woman with a 3 week–old T9 fracture and a 53 year–old man with an 8 month–old T11 fracture. Intraosseous venography, performed to detect communications with the central or epidural veins, preceded cement injections.

Results:

Venography showed retention of contrast material within the vertebrae. Prior to cement injection, normal saline was injected to wash–out the contrast material so that this would not impair visualization of the cement during its injection. Wash–out of contrast was monitored by fluoroscopy. Transient increases in the height of the compressed vertebrae were visualized and recorded on videotape. Both patients had marked pain relief.

Discussion and Conclusion:

Pain relief is common following percutaneous vertebroplasty; the mechanism remains unknown. Proposed mechanisms have included neurolysis due to the exothermic reaction of the cement and mechanical strengthening. Visible fracture instability suggested that this was the source of pain. Vertebroplasty was felt to have secured the fracture fragments. Pain relief following fracture stabilization also suggested that instability had been the cause of pain. Fluoroscopically apparent fracture instability in patients undergoing vertebroplasty has not previously been reported. Lesser degrees of instability may be common and would not be visible. Our observations suggest that pain may be due to non–healing, unstable fractures and that pain relief provided by vertebroplasty is due to internal fixation of such fractures.