Preliminary report of modified expansive laminoplasty in the treatment of thoracic ossification of the ligamentum flavum

Abstract

Objective: This study was performed to evaluate the role of posterior suspension of the laminae-ossification of the ligamentum flavum complex combined with miniplate fixation (modified expansive thoracic laminoplasty) in treating thoracic ossification of the ligamentum flavum (TOLF).

Methods: Eight patients with TOLF treated by modified expansive thoracic laminoplasty were retrospectively analyzed. Their general information, operative time, intraoperative blood loss, and postoperative complications were recorded. Neurological functional recovery was evaluated by the modified Japanese Orthopaedic Association (mJOA) score and Hirabayashi recovery rate preoperatively, postoperatively, and at the final follow-up. Preoperative and postoperative imaging was performed, and the decompression range and internal fixation positioning were evaluated.

Results: The mJOA score significantly improved from 4.63 points preoperatively to 9.0 points at the final follow-up (Hirabayashi recovery rate of 77.75%). Postoperative computed tomography and magnetic resonance imaging revealed sufficient decompression of the surgical segment. At the final follow-up, the internal implants were well-placed, the lamina-ligamentum flavum complex showed no significant displacement, and neurological functional recovery was satisfactory.

Conclusion: Surgical treatment of TOLF is complicated and high-risk. Characterized by simplicity and sufficient decompression, modified expansive thoracic laminoplasty can reduce the risk of cerebrospinal fluid leakage and nerve injury with satisfactory neurological functional recovery.

Keywords: Thoracic ossification of the ligamentum flavum; decompression; diagnostic imaging; expansive laminoplasty; neurological functional recovery; spinal cord compression.

Figure 1.

Flowchart of patient selection. TOLF, thoracic ossification of the ligamentum flavum.

Figure 2.

Schematic diagram of the surgery. (a) Adequate exposure of the bony structure from the spinous process to the base of the transverse process. (b), (c) The T11 and T12 laminae were isolated en bloc, enabling slow posterior suspension of the laminae–ossification of the ligamentum flavum complex (LOC). (d) The miniplate was bent and placed at the gap between the transverse process and laminae, and the suspended LOC was then secured to the transverse processes bilaterally with the miniplate and screws.

Figure 3.

(a) Axial and (b) sagittal computed tomography demonstrated the ossified ligamentum flavum protruding into the spinal canal at the level of T11–12, resulting in severe canal stenosis. (c) Axial and (d) sagittal magnetic resonance imaging showed low-signal masses behind the spinal cord in the spinal canal with compression and degeneration of the spinal cord. Postoperative (e) axial and (f) sagittal computed tomography demonstrated retropositioning of the laminae–ossification of the ligamentum flavum complex, a partial defect in the medial wall of the pedicle, and an evidently expanded vertebral canal volume. At the last follow-up (14 months postoperatively), thoracic (g) anteroposterior and (h) lateral X-rays demonstrated good positioning of the miniplates. (i) Axial and (j) sagittal magnetic resonance imaging revealed an expanded vertebral canal volume of the decompressive segments, no evident spinal cord compression, and unobstructed ventral and dorsal cerebral spinal fluid flow.