XU Bao-shan, HU Yong-cheng, YANG Qiang, XIA Qun, MA Xin-long , JI Ning

Background  Percutaneous vertebroplasty (PVP) has become a popular procedure for painful vertebral osteoporotic fracture (VOF), with immediate pain relief and improved mobility; however, polymethylmethacrylate (PMMA) injected into the vertebral body is not absorbable and little information is available concerning the long-term results. In this retrospective study, we evaluated the long-term clinical results and radiological changes after PVPs for VOFs.
Methods  Fifty-one patients with VOFs were treated by PVPs with PMMA between 2000 and 2004. After >7 years of follow-up, eight patients had died from causes unrelated to the intervention and 12 patients were lost to follow-up, thus leaving 31 patients available for evaluation with an average length of follow-up of 9.2 years (follow-up rate, 72.1%). Among these 31 patients, the PMMA was injected at 43 levels with a mean volume of 4.3 ml per level (range, 2-6 ml). The pain was assessed with a visual analog scale (VAS), and the mobility was graded as walking without difficulty (grade 1), walking with assistance (grade 2), and bedridden (grade 3). Plain radiographs and computed tomography (CT) were obtained and assessed pre-operatively, immediately post-operatively, and after 7 years of follow-up. The PMMA, vertebral height, and Cobb angle were assessed and compared.
Results  All of the patients experienced pain relief and improved mobility after intervention and during the follow-up period. Cement leakage was detected in post-operative CT scans in 9 of 51 patients, but without neurological compromise. For the 31 patients followed up over 7 years, the VAS decreased from 8.3±2.6 pre-operatively, to 2.1±1.6 immediately post-operatively, and 1.0±0.9 at the final follow-up evaluation, with significantly improved mobility. Additional compression fractures occurred at adjacent levels in three patients, and there were no new fractures at the augmented vertebrae. Based on a review of the radiographs, neither loose nor displaced cement was detected. The changes in vertebral height and Cobb angle were not significant. On CT scans, the cement closely contacted or infiltrated the trabecular bone. The boundary between the cement and trabecular bone was indistinct and there was no evident radiolucent gap between the cement and trabecular bone.
Conclusions  At an average follow-up of 9.2 years, PVPs provided sustained pain relief and improved mobility in patients with VOFs. The PMMA injected into the vertebral body combined closely with the host trabecular bone without adverse reactions.