Minimally invasive surgery for resection of ossification of the ligamentum flavum in the thoracic spine

INTRODUCTION Thoracic ossification of the ligamentum flavum (TOLF) is a common cause of progressive thoracic myelopathy. Surgical decompression is commonly used to treat TOLF. AIM To evaluate the clinical outcomes of microsurgical decompression of TOLF via a paraspinal approach, using a percutaneous tubular retractor system. MATERIAL AND METHODS First, three-dimensional (3D) image reconstruction and printed models were made from thin computed tomography scans for each patient. Then, 3D computer-assisted virtual surgery was performed using the 3D reconstruction to calculate the precise location and sizes of the bone window and the angle of insertion of the percutaneous tubular retractor system. In total, 13 patients underwent the surgery through the percutaneous micro channel unilateral vertebral approach under electrophysiological monitoring. Five days after the surgery, increased creatine phosphokinase levels returned to preoperative levels. The Japanese Orthopedic Association (JOA) score was improved and computed tomography reconstruction and magnetic resonance imaging of the thoracic spine showed that decompression was achieved without injuries to the spinal cord or nerve root. The stability of the spine was not affected, nor were any deformities of the spine detected. Finally, nerve functional recovery was achieved with minimal injury to the paraspinal muscle, articulum, spinous process and ligament. RESULTS The mean operative time was 98.23 ±19.10 min, and mean blood loss was 19.77 ±5.97 ml. At a mean follow-up of 13.3 months (median: 12 months), the mean JOA score was 7.54 ±1.13 at the final follow-up, yielding a mean RR of 49.10 ±15.71%. Using The recovery rate, 7 (53.85%) patients had good outcomes, 5 (38.46%) patients had a fair outcome, and 1 (7.69%) patient had poor outcomes, indicating significant improvement by the final follow-up examination (p < 0.05). CONCLUSIONS The 3D printed patient model-based microsurgical resection of TOLF via the paraspinal approach can achieve decompression of the spinal canal with minimal complications, faster recovery and improved stability of the vertebral body.