Isocentric Navigation of Percutaneous Endoscopic Transforaminal Discectomy at the L5/S1 Level in Difficult Puncture Cases: A Technical Note.

BACKGROUND Accurate puncture during percutaneous transforaminal endoscopic discectomy at the L5/S1 level in cases with high iliac crest and narrow foramen were difficult, even though the difficulties of foraminoplasty could be overcome by advanced instruments like reamers. OBJECTIVES The report aimed to describe an isocentric navigation technique with a definite pathway in difficult puncture cases at the L5/S1 level. STUDY DESIGN Technical note. SETTING Difficult punctures were defined as over 10 punctures of the needle before obtaining an ideal puncture location by senior surgeons with experience of over 500 percutaneous endoscopic transforaminal discectomy (PETD) cases. METHODS A total of 124 punctures were recorded in 11 difficult puncture cases at the L5/S1 level. A definite pathway was created by an isocentric navigation theory, which was based on a surface locator and an arch-guided device. The surface locator was used to rapidly and accurately identify the puncture target with the recognition of the surrounding rods under fluoroscopy. The arch-guided device can ensure that the puncture target always remains at the center of a virtual sphere. We recorded the puncture times, fluoroscopy exposure times, radiation exposure time, operative time, visual analog scale (VAS) score, Japanese Orthopeadic Association (JOA) score, and patient satisfaction. RESULTS The average puncture times were significantly reduced to 1.27 with the arch-guided device compared with conventional puncture methods (P < 0.05). The average operative time was 90.09 ± 11.00 minutes and the fluoroscopy times were 53.36 ± 5.85. The radiation exposure time was 50.91 ± 5.20 seconds. VAS score of leg and back pain, as well as JOA score, were all significantly improved after surgery (P < 0.05). The excellent and good rate of satisfaction was 90.91%. No major complications, including cerebral fluid leakage, surgical infection, and postoperative nerve root injury, were recorded in this small sample. LIMITATIONS This was a small-sample study with a short follow-up. CONCLUSIONS The novel isocentric navigation technique with a definite pathway is practical and effective in reducing puncture times among difficult puncture cases at the L5/S1 level, which may contribute to the capacity of PETD at the L5/S1 level.