Utility of Computed Tomography-Guided Navigation for Full-Endoscopic Pars Crisscross Decompression: A Technical Note

BACKGROUND: Full-endoscopic decompression for L5 isthmic spondylolisthesis is technically demanding due to the intricate "pars crisscross" anatomy. The inherent visualization limitations of endoscopic surgery-specifically the lack of depth perception and a restricted field of view-can make anatomical orientation difficult, increasing the risk of incomplete decompression or iatrogenic injury. OBJECTIVE: To describe a navigation-assisted full-endoscopic pars crisscross decompression (FE-PCD) technique designed to overcome these anatomical challenges. METHODS: We performed this navigation-assisted FE-PCD technique in 3 consecutive patients with stable L5 isthmic spondylolisthesis. An O-arm-based intraoperative navigation system was utilized to provide real-time 3-dimensional (3D) guidance. A "virtual probing" technique was employed to visualize the drill tip relative to the 3D anatomical reconstruction, facilitating the precise identification of the S1 superior articular process, floating lamina, L4 inferior articular process, and the ragged edge. RESULTS: All procedures were successfully completed without intra- or postoperative complications. The use of navigation effectively compensated for the limited endoscopic view, allowing for the clear differentiation of deep bony structures and precise resection of the impinging ragged edge. CONCLUSION: Our preliminary experience suggests that navigation-assisted FE-PCD is a potentially feasible and safe technique. It mitigates the risks associated with the complex pars crisscross anatomy by providing a reliable 3D roadmap, thereby preventing disorientation, ensuring adequate decompression, and optimizing the extent of facet resection. CLINICAL RELEVANCE: Full-endoscopic pars crisscross decompression (FE-PCD) is an effective but technically demanding procedure for stable isthmic spondylolisthesis due to the complex 3D anatomy of the "pars crisscross." This integration enhances surgical safety by preventing intraoperative disorientation, ensuring adequate decompression, and minimizing iatrogenic facet resection, thereby potentially shortening the learning curve for this challenging endoscopic technique.