Full-Endoscopic Decompression with the Application of an Endoscopic-Matched Ultrasonic Osteotome for Removal of Ossification of the Thoracic Ligamentum Flavum

Background: Resection of the ossification of the thoracic ligamentum flavum (OTLF) with ahigh-speed burr may cause a high rate of perioperative complications, such as dural lacerationand/or iatrogenic spinal cord injury.Objectives: The aim of this study was to investigate the safety and feasibility of the endoscopicmatchedultrasonic osteotome in full-endoscopic spinal surgery for direct removal of OTLF.Study Design: Retrospective study.Setting: All data were from Honghui Hospital in Xi’an.Methods: This study conducted between December 2017 and December 2018, included 27consecutive patients who met the study criteria, had single-level OTLF, and underwent fullendoscopicdecompression under local anesthesia. The postoperative follow-up was scheduledat 1, 3, 6, and 12 months postoperatively. Outcomes evaluations included the Visual AnalogScale (VAS) score for lower extremity pain and the modified Japanese Orthopaedic Association(mJOA) score and improvement rate for the assessment of thoracic myelopathy. Removal ofOTLF was measured by comparing the pre- and postoperative computed tomography (CT) andmagnetic resonance imaging (MRI) scans.Results: The operation was completed in all patients without conversion to open surgery.The operation time ranged from 65 to 125 minutes (average, 83.7 ± 12.3 minutes). Allpatients were followed up for 12 to 18 months, with an average follow-up of 14.3 ± 1.3months. Satisfactory neurologic decompression was confirmed by postoperative CT and MRI,and no revision surgery was required. The VAS and mJOA scores showed statistically higherimprovement at the 1-month follow-up and the last follow-up compared with the preoperativeassessment (P < 0.05). According to the improvement rate at the final follow-up, 20 cases wereclassified as good, 6 cases were fair, and 1 case remained unchanged.Limitations: A single-center, noncontrol study.Conclusions: The endoscopic-matched ultrasonic osteotome can be considered quite safeand feasible for direct removal of OTLF during full-endoscopic spinal surgery in strictly selectedpatients, as this allows for effective direct decompression of OTLF while minimizing trauma andinstability. In addition, because of the design characteristics of the ultrasonic osteotome, surgicalcomplications, especially dural tears and spinal cord injury, can also be effectively controlled.Key words: Percutaneous endoscopic spinal surgery, ultrasonic osteotome, ossification ofthoracic ligamentum flavum, microsurgery, thoracic myelopathy, minimally invasive procedures