Objective: To explore the safety and clinical efficacy of using the ultrasonic bone scalpel (UBS) system for laminectomy, osteotomy of posterior longitudinal ligament (PLL) ossification, combined with correction of kyphosis deformity in the treatment of multilevel thoracic ossification of the PLL.

Methods: A retrospective analysis was conducted on patients with multilevel thoracic ossification of the PLL who underwent laminectomy, osteotomy of PLL ossification, combined with correction of kyphosis deformity using the UBS system from January 2020 to April 2023. There were 3 males and 5 females, aged 41 to 67 (mean 57.12±8.37) years; the duration of symptoms ranged from 3 to 74 (mean 33.37±23.40) months. Symptoms included progressive bilateral leg numbness and weakness, unsteady gait, and back pain in 3 cases, and urinary and fecal dysfunction in 5 cases. Seven cases showed increased muscle tone in the lower limbs, exaggerated tendon reflexes, and positive Babinski sign, while 1 case showed decreased muscle strength in the lower limbs, reduced skin sensation, decreased Achilles tendon reflex, and negative pathological signs. Preoperative Japanese Orthopaedic Association (JOA) thoracic spinal cord function score was 4.25±0.86 (3–6) points, and visual analogue scale (VAS) score was 6.87±0.99 (5–8) points. All 8 patients had multilevel thoracic ossification of the PLL, with ossification involving 4–8 segments; 5 cases were complicated by multilevel ligamentum flavum ossification. The Cobb angle of kyphosis in the segment with spinal canal stenosis was 34.62°±10.76° (24°–55°). General surgical conditions and complications were recorded, and the preoperative and postoperative JOA scores, JOA recovery rate, VAS scores, Cobb angle of kyphosis in stenotic segments, and improvement rate were statistically analyzed to evaluate the clinical efficacy and safety of the surgery.

Results: The follow-up period ranged from 12 to 26 (mean 18.25±4.68) months, with a surgical duration of 210 to 340 (mean 271.62±48.38) minutes and blood loss of 900 to 2100 (mean 1458.75±458.05) ml. The number of laminectomies ranged from 4 to 8 (mean 6.12±1.35) segments. Complications: Dural tear and cerebrospinal fluid (CSF) leakage occurred in 3 cases intraoperatively, with 2 cases undergoing tight suturing, pressure dressing, and drainage for 4–5 days, achieving primary wound healing, and 1 case undergoing intraoperative artificial dural suturing without postoperative CSF leakage; there were no complications such as loosening of internal fixation, broken nails, or rods. There was no aggravation of neurological symptoms after surgery. At the last follow-up, imaging showed no significant progression of ossification; the JOA thoracic spinal cord function score increased from 4.25±0.86 (3–6) points preoperatively to 9.75±0.70 (9–11) points postoperatively, with a statistically significant difference (t=13.015, P<0.001); JOA recovery rate was (81.06±10.93)% (67%–100%), with excellent results in 5 cases, good results in 3 cases, fair results in 0 cases, and poor results in 0 cases. VAS score decreased from 6.87±0.99 (5–8) points preoperatively to 1.37±0.74 (1–3) points postoperatively, with a statistically significant difference (t=11.881, P<0.001); Cobb angle of kyphosis in stenotic segments decreased from 34.62°±10.76° (24°–55°) to 22.12°±8.28° (8°–38°), with a statistically significant difference (t=7.395, P<0.001), and improvement rate was (36.51±14.20)% (17%–64%).

Conclusions: The application of UBS system for laminectomy, osteotomy of ossification blocks, combined with kyphosis correction technique in the treatment of long-segment thoracic ossification of the PLL is safe and effective, relatively simple to operate, and is a feasible approach.

Thoracic vertebrae, Spinal stenosis, Ossification of PLL, Curative effect