Effect of dominant cement distribution zone on pain relief after unipedicular percutaneous vertebroplasty.

BACKGROUND

Cement location within the vertebral body may influence pain relief after unipedicular vertebroplasty. We tested a simple four-zone classification of dominant intravertebral cement distribution in osteoporotic vertebral compression fractures.

METHODS

We retrospectively analyzed 425 patients treated from 2021 to 2024. On postoperative imaging, the vertebral body was divided into four equal zones (Zones 1-4) and the zone with the greatest cement accumulation was recorded. Pain was measured with the visual analog scale (VAS) before and after the procedure; change in VAS was the primary endpoint. Multivariable linear regression modeled change in VAS. Logistic regression modeled clinical response (change in VAS > 4).

RESULTS

Mean VAS decreased from 7.63 ± 0.84 to 3.31 ± 1.06 (p < 0.001), with mean change in VAS of 4.32 ± 1.38. Change in VAS differed across zones (p < 0.001), highest in Zone 4 and lowest in Zone 1. Complications occurred in 45.4% (primarily cement leakage) without permanent neurological deficit. In linear regression, dominant zone independently predicted change in VAS (B = 0.852; standardized β = 0.546; p < 0.001) and overall fit was strong (R² = 0.724; adjusted R² = 0.717). In logistic regression (n = 387), Omnibus χ² = 280.646 (df = 13, p < 0.001) and Nagelkerke R² = 0.729; zone, preoperative VAS, and cement volume were independent predictors. Calibration was acceptable (Hosmer-Lemeshow p = 0.941). Compared with Zone 4, Zones 1-3 showed lower odds of response; higher baseline VAS increased the odds.

CONCLUSIONS

Dominant cement zone strongly predicts pain improvement after unipedicular vertebroplasty and may serve as a practical procedural quality marker.