A Novel "Sphere Center Method" for Optimizing Puncture Trajectory in Percutaneous Vertebroplasty via Kambin’s Triangle: A 3D Anatomical and Cadaveric Validation Study

Purpose: To introduce and validate a novel "Sphere Center Method" (SCM) for establishing the optimal puncture trajectory and safe range for percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) in treating osteoporotic vertebral compression fractures (OVCFs). This study also aimed to define a new three-dimensional safe zone, the "Kambin-PVP/PKP Pentagonal Pyramidal Safety Zone" (K-PPPSZ), based on this method. Methods: Retrospective CT data from 30 healthy subjects were used to create 3D models of the L1-L5 vertebrae. The SCM established a spatial Cartesian coordinate system centered on the vertebral body's geometric center to parametrically model and identify the optimal puncture path through Kambin's triangle while avoiding critical neurovascular structures. The K-PPPSZ was then defined based on the identified safe boundaries. The feasibility of the SCM was validated through guided punctures on two lumbosacral cadaver specimens. Results: The SCM successfully identified optimal puncture paths for the L2-L5 vertebrae. Descending from L2 to L5, the optimal tilt angle decreased while the offset angle increased, indicating a caudolateral shift of the skin puncture point. The L3 vertebra demonstrated the largest puncture inclusion range and maximum puncture radius, suggesting a greater safety margin. Cadaveric validation confirmed precise needle placement at the geometric center of the target vertebrae using SCM-derived guides. Conclusion: The SCM provides a precise, repeatable, and data-driven approach for preoperative planning in PVP/PKP. The proposed K-PPPSZ offers a more accurate anatomical definition for this surgical corridor, enhancing the safety and standardization of vertebral body puncture procedures via Kambin's triangle.