The clinical effect of floating island laminectomy technique for severe thoracic spinal stenosis and myelopathy caused by ossification of the ligamentum flavum: a retrospective study

Background Severe thoracic ossification of the ligamentum flavum often leads to thoracic spinal canal stenosis and spinal cord injury, which generates severe symptoms. Generally, patients required surgery and aggravated spinal cord function impairment is a common complication. We propose a novel surgical technique to remove the ossified ligamentum flavum with the adhesive dura as a floating island. The purpose of this study was to evaluate the clinical efficacy and safety of floating island in the treatment of severe ossification of ligamentum flavum. Methods A total of 31 patients with thoracic spinal stenosis and myelopathy caused by thoracic ossification of the ligamentum flavum from January 2019 to April 2022 were included in the study and were followed up at 1, 3, 6, and 12 months, respectively. All patients were treated with floating island laminectomy technique. Neurological function was assessed by the modified Japanese Orthopaedic Association (mJOA) scoring system before and after operation and the rate of improvement was calculated. Perioperative complications were also recorded in this study. Results All 31 patients were successfully completed by the same professional surgery team. The average operative time was 207.74 ± 58.54 minutes, and the average intra-operative blood loss was 406.45 ± 217.85 ml. The mJOA score at 1 month, 3 months, 6 months and 12 months after surgery increased from 4.68 ± 0.60 to 6.71 ± 0.73, 7.35 ± 0.76, 8.45 ± 0.85 and 9.06 ± 0.81, respectively. The mJOA score after surgery was significantly higher than before (P < 0.001). The recovery rate was (32.41 ± 8.55)%, (42.57 ± 9.00)%, (60.12 ± 11.07)% and (69.76 ± 11.38)% for 1 month, 3 months, 6 months and 12 months after surgery, respectively. Postoperative complications included dural tear in 13 cases (41.9%), defect in 10 cases (32.2%) and cerebrospinal fluid leakage in 10 cases (32.2%). There was no recurrence of ossification or postoperative thoracic vertebra deformity in patients with aggravated neurological injury. Conclusion The results of this study indicate that although the incidence of cerebrospinal fluid leakage is a little high after operation, the floating island laminectomy method for the treatment of thoracic ossification of the ligamentum flavum is still safe and effective, which can effectively avoid the aggravation of neurological symptoms and enable patients to obtain satisfactory neurological function improvement and functional recovery.