T-saw–free osteotomy using an ultrasonic bone scalpel for en bloc resection of spinal tumors: surgical technique and outcomes

Abstract Background Total en bloc spondylectomy (TES) requires precise vertebral osteotomy to achieve adequate oncologic margins while preserving adjacent neurovascular structures. This technical note describes a Threadwire saw (T-saw) free osteotomy technique using an ultrasonic bone scalpel (UBS) during single-stage posterior TES and reports the perioperative and oncologic outcomes of a consecutive clinical series. Methods Sixty-nine consecutive patients underwent single-stage posterior TES using a UBS between December 2017 and January 2024. The surgical technique is described in detail. Patient demographics, operative variables, pathological margins, perioperative complications, neurological outcomes, and survival were retrospectively reviewed. Results Fifty-four patients had primary spinal tumors and 15 had solitary spinal metastases. The median operative time was 330 min (IQR, 261–402), and the median estimated blood loss was 1,500 mL (IQR, 1,000–2,300). Wide, marginal, and intralesional margins were achieved in 62 (89.9%), 6 (8.7%), and 1 (1.4%) patients, respectively. No intraoperative dural tears, spinal cord injuries, major vascular injuries, or UBS-related neurovascular complications occurred. Seventeen patients (24.6%) experienced postoperative complications, most commonly surgical site infection (13.0%) and pleural effusion (10.1%). During a median follow-up of 46 months, the 5-year local recurrence-free survival rate was 86.4%. Conclusion UBS-assisted single-stage posterior TES is a feasible osteotomy technique that enables controlled bone cutting while achieving acceptable surgical margins and perioperative outcomes in this consecutive series. Further comparative studies are warranted to determine its effectiveness relative to conventional saw-based techniques.