Endplate-to-endplate cement contact and 24-month outcomes after unilateral percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a single-center retrospective cohort study

Background Bone cement distribution may influence load transfer and late structural failure after vertebral augmentation. However, the association between endplate contact and clinical outcomes remains difficult to estimate due to confounding factors. Methods This retrospective cohort study included 620 patients who underwent unilateral percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures (OVCFs) at a single institution. Cement distribution was classified as contact with neither endplate (group I), the superior endplate only (group II), the inferior endplate only (group III), or both endplates (group IV). The primary outcome was time to postoperative vertebral refracture within 24 months. Secondary outcomes included longitudinal visual analogue scale (VAS) scores, Oswestry Disability Index (ODI), vertebral recompression, radiographic restoration, cement leakage, and perioperative measures. Confounding was addressed using stabilized multinomial inverse probability of treatment weighting (IPTW). Repeated outcomes were analyzed using generalized estimating equations (GEE), and time to refracture was analyzed using Cox regression. Restricted cubic splines, subgroup analyses, and 10-fold cross-validation were performed. Results Among 620 patients, 150 refractures (24.2%) occurred. Event rates were 30.9%, 26.6%, 25.7%, and 15.2% in groups I–IV, respectively (log-rank P = 0.0069). After weighting, the maximum standardized mean difference (SMD) decreased from 0.231 to 0.053. At 24 months, group IV had lower adjusted VAS scores (mean difference, −0.72; 95% confidence interval ( CI ), −0.93 to −0.51) and ODI scores (mean difference, −6.75; 95% CI , −8.35 to −5.15) than group I. In the Cox model, group IV was associated with a lower refracture hazard (hazard ratio ( HR ), 0.40; 95% CI , 0.25–0.64). Independent risk markers included older age, female sex, lower bone mineral density (BMD) T-score, prior fragility fracture, two-level treatment, intravertebral cleft, intradiscal leakage, absence of anti-osteoporosis treatment, chronic glucocorticoid exposure, and deviation from a midrange cement volume. The association for group IV was stronger during months 0–12 than during months 13–24. Conclusions Cement contact with both endplates was associated with better long-term pain and functional outcomes and greater refracture-free survival after extensive adjustment. However, the adjusted 24-month differences in VAS and ODI did not exceed commonly accepted minimal clinically important difference (MCID) thresholds, so the clinical magnitude remains uncertain. These findings provide useful prognostic information for surgical planning, although prospective validation is warranted.