Thoracolumbar fascia injury and other independent predictors of long-term residual low back pain 3 months after percutaneous kyphoplasty for thoracolumbar osteoporotic vertebral compression fractures

To identify independent risk factors for persistent residual low back pain at 3 months after isolated percutaneous kyphoplasty (PKP), and provide standardized clinical evidence for preoperative high-risk patient screening, standardized intraoperative manipulation, and long-term postoperative anti-osteoporosis intervention in patients with thoracolumbar osteoporotic vertebral compression fractures (OVCF). A single-center retrospective cohort study was conducted. A total of 138 consecutive patients who received PKP only (all PVP cases excluded) from January 2023 to June 2025 were enrolled. The primary endpoint was defined as persistent residual low back pain with VAS ≥ 4 at the 3-month postoperative follow-up, rather than the original composite 1-week plus 1-month pain criterion. Baseline demographics, preoperative multi-modal MRI/CT imaging markers, intraoperative surgical parameters, and postoperative medication records were fully collected. The 3-month Oswestry Disability Index (ODI) was recorded as a secondary functional outcome indicator. All radiological images were blindly evaluated by two senior spinal surgeons, and inter-observer Kappa coefficients were calculated to verify evaluation reproducibility. Univariate screening combined with collinearity diagnosis and LASSO regression was applied to select candidate predictors. Multivariate unconditional Logistic regression was constructed. The Hosmer–Lemeshow test and events-per-variable (EPV) ratio were calculated to assess model calibration and avoid overfitting. This study solely focuses on risk factor identification; predictive tools including ROC curve, AUC and nomogram were not developed due to restrictions on exporting complete individual-level raw clinical datasets from the hospital information system, which will be completed in subsequent independent cohort research. The overall incidence of 3-month persistent residual low back pain after PKP was 29.71% (41/138). Inter-observer Kappa values for all imaging indicators exceeded 0.8, indicating excellent evaluative consistency. Univariate analysis demonstrated significant intergroup differences in age ≥ 75 years, BMD T-value < − 2.5 SD, preoperative thoracolumbar fascia injury, asymmetric bone cement distribution, bone cement leakage, and non-standardized anti-osteoporosis treatment (all P < 0.05). No statistically between-group differences were observed in gender, BMI, preoperative VAS, vertebral compression ratio, cement injection volume, fracture segment, leakage subtype, paraspinal muscle fatty degeneration, intravertebral vacuum cleft, and facet joint injury (all P > 0.05). After collinearity detection and LASSO variable compression, four independent risk factors were confirmed by multivariate Logistic regression: BMD T-value < − 2.5 SD (OR = 2.211, 95%CI: 1.368 ~ 3.576, P < 0.001), preoperative thoracolumbar fascia injury (OR = 3.651, 95%CI: 2.122 ~ 6.283, P < 0.001), asymmetric bone cement distribution (OR = 2.379, 95%CI: 1.430 ~ 3.961, P < 0.05), and non-standardized anti-osteoporosis treatment (OR = 2.115, 95%CI: 1.294 ~ 3.455, P < 0.05). Model diagnostic results: Hosmer–Lemeshow χ²=6.927, P = 0.544; EPV = 10.25, satisfying the EPV ≥ 10 standard without overfitting risk. The observation group exhibited significantly higher 3-month ODI scores than the control group ( P < 0.001). Severe osteoporosis, preoperative thoracolumbar fascia injury, intraoperative asymmetric bone cement filling, and irregular long-term anti-osteoporosis management are independent high-risk factors for persistent residual low back pain 3 months after isolated PKP. Clinicians should integrate bone mineral density measurement and preoperative MRI thoracolumbar fascia assessment to screen high-risk patients, ensure bilateral symmetric cement dispersion under intraoperative fluoroscopic monitoring, and implement continuous standardized anti-osteoporosis therapy postoperatively to reduce chronic back pain and improve long-term spinal function in elderly OVCF patients.