Percutaneous Kyphoplasty Warning Line for Preventing Bone Cement Leakage

‌ Background ‌ With the global aging population, osteoporotic fractures—particularly osteoporotic vertebral compression fractures (OVCFs)—have emerged as a critical health concern, severely impacting the quality of life in elderly individuals. Percutaneous kyphoplasty (PKP) has demonstrated significant clinical efficacy in treating OVCFs by stabilizing fractures and alleviating pain‌. However, bone cement leakage during PKP remains a major complication, posing risks of spinal cord compression. This study aimed to establish a radiographic "warning line" to predict and mitigate posterior vertebral wall cement leakage during PKP. ‌ Methods‌ From February 2018 to September 2022, 88 patients (106 vertebral bodies) with OVCFs treated by unilateral PKP at a single center were retrospectively analyzed. Inclusion criteria required intraoperative X-ray confirmation of bone cement diffusion reaching the posterior vertebral margin. Postoperative three-dimensional CT scans classified vertebrae into Group A (no leakage, n=44) and Group B (leakage, n=62). Parameters including age, bone mineral density (T-score), balloon pressure, contrast volume, and cement volume were compared. The posterior vertebral wall was divided into upper, middle, and lower thirds to assess leakage distribution. Lateral X-ray measurements defined the warning line (line b) as the apex of cement diffusion parallel to the posterior vertebral margin (line a), with the ratio ab/ac calculated to quantify its position relative to the sagittal diameter. ‌ Results‌ All patients exhibited significant pain relief (preoperative VAS: 5.69±1.15 vs. postoperative: 1.20±0.79, P <0.05) without neurological complications. Posterior vertebral wall leakage occurred in 58.5% (62/106) of cases, predominantly in the middle (61.1%) and lower thirds (66.7%) (P<0.05)‌. No significant differences existed between groups in age, bone density, or procedural parameters ( P >0.05). The warning line ratio (ab/ac) in Group A was 6.8±2.17%, indicating that maintaining cement diffusion anterior to this threshold correlated with reduced leakage risk. ‌ Conclusions‌ PKP is a safe and effective intervention for OVCFs, but posterior vertebral wall leakage remains prevalent. Cement dispersion exceeding 6.8% of the sagittal diameter from the posterior margin significantly increases leakage risk, particularly in the middle and lower thirds of the vertebral wall‌. The proposed warning line provides a practical intraoperative radiographic marker to enhance procedural safety and reduce complications.