New vertebral osteoporotic compression fractures after percutaneous vertebroplasty: retrospective analysis of risk factors.

PURPOSE: To investigate risk factors for new vertebral compression fractures (VCFs) after vertebroplasty.

MATERIALS AND METHODS: The authors analyzed the occurrence of new VCFs in 70 patients who had previously undergone vertebroplasty for the treatment of one VCF. The following covariates were analyzed: age, sex, body weight, height, body mass index (BMI), treated vertebral level, relative distance between treated vertebrae and new VCFs, pre-existing untreated VCFs, gas-containing vertebrae before treatment, and surgical approach. Surgical variables, including cement leakage into the disk, anterior vertebral height restoration, and kyphosis correction of treated vertebrae were also analyzed. A Cox proportional hazards regression analysis was used to determine the relative risk of new adjacent VCFs. The Kaplan-Meier method was used to calculate mean fracture-free rate over time.

RESULTS: Seventy patients were reviewed, with a mean follow-up of 20.0 months +/- 10.2 (range, 6-48 months). We identified 22 new fractures in 19 of the 70 patients (27%), with 16 adjacent and six nonadjacent VCFs. The mean time to new fracture was 10.6 months +/- 9.5, and there was no significant difference in time to adjacent or nonadjacent VCF. Increased risk of VCF was associated with proximity to the treated vertebra, greater kyphosis correction, and low patient BMI. The 1-year fracture-free rate was 79.5%.

CONCLUSIONS: New VCFs are common in patients with a low BMI, which suggests osteoporosis as a mechanism of fracture.