Laminectomy for the Removal of Thoracic Ossification of the Ligamentum Flavum (TOLF) Using Ultrasonic and Conventional Osteotomes

In this video we'll share a case using laminectomy for the removal of thoracic ossification of the ligamentum flavum using ultrasonic and conventional osteotome. Thoracic ossification of the ligamentum flavum is a well-known cause of thoracic spinal stenosis that has been identified as a primary cause of thoracic myelopathy. The conservative treatment is generally ineffective, so once the TOLF is symptomatic, decompression is almost the only effective method.

Several types of surgical methods has been shown to be effective for TOLF including laminoplasty, laminectomy, and lamina fenestration. There's a high rate of perioperative complications, such as dural laceration and/or iatrogenic spinal cord injury. Here, we report in detail a method for laminectomy in thoracic spine using ultrasonic osteotome combined with conventional osteotome to resect the lamina, which is effective and safer for the treatment of TOLF.

Ethical approval was obtained from the Medical Ethics Committee of the author's hospital, and informed the consent was obtained from each patient. Here is a brief history of the patient. And we find ossification of the ligamentum flavum between T10 and 11.

Under general anesthesia, the patient was placed in prone position. Neurophysiological monitoring involving SSEPs and MEPs was conducted throughout the surgery. The TOLF levels were identified with a C-arm before operation.

Surgery area was disinfected using PVP-I, and draped with sterile surgical towels. They involved the levels of TOLF were identified intra-operatively via a C-arm X-ray machine. A longitudinal midline incision was made over the spinous process extending from the spinous process above to the spinous process below the level of pathology.

The posterior bony structure including the spinous processes, bilateral lamina, and zygapophyseal joints of the involved levels were exposed using unipolar electrotome. The pedicle screw entry points were determined based on anatomical landmarks according to the AO method, which is the intersection between the midlines of the facet joint and transverse process. Pedicle marker pins were inserted to mark the pedicle screw entry points, and also used as a reference for the lateral border of the thoracic spinal cord.

The spinous processes, along with the supraspinous and interspinous ligaments were then removed using a bone rongeur from the cranial to the caudal end of the decompression zone. Usually a part of the spinous process was maintained to help removing the lamina. The incision was irrigated with saline to identify bleeding sites, a sterilized medical cera sryptica was used for hemostasis on the residual supraspinous.

A rectangular decompression zone was identified as a area between the midpoints of the facet joints bilaterally and between the inferior portions of the superior lamina and superior portions of the inferior lamina of the TOLF involved segments. The ultrasonic osteotome was used to cut the lamina horizontally on cranial and the caudal ends of the decompression zone. And longitudinally between the midpoints of the facet joints bilaterally.

The cutting can be performed for multiple times until your feeling the lamina is cutting through. The conventional osteotome was used to lever the lamina upwards in turn from side to side. The bounce sound of the bone indicates the lamina has been completely cut off.

After lamina was loosened, one or two towel clamps were used to clamp the root of the spinous process, and the entire lamina is elevated carefully. When there is adhesion between the ossified tissue and the dura matter, a nerve dissector can be used for this attachment. The remaining articular process and the edge of the lamina on both sides were further detected and trimmed using Kerrison Rongeur to ensure fully decompression.

After thoroughly hemostasis with bipolar electrocoagulation and cera styptica, the dural surface was covered with gelatin sponge or fluid gelatin, and cottonoids. Then, the pedicle marker pins were replaced by pedicle screws. In some cases, the bone fragments from the vertebral lamina were minced and implanted bilaterally between the transverse processes.

Titanium rods were connected and screw nuts were tightened. Throughout the operation, hemostasis were achieved using bipolar electrocoagulation and cera styptica. Jackson-Pratt drainage was routinely performed for 24 to 48 hours in patient without the dura tears.

Dehydration management and neurotrophic medications were administered after the operation. Intravenous methylprednisone was administrated for three days. Patients were instructed to perform rehabilitation exercise to help functional recovery.

The muscle strength was improved remarkably and the patient was discharged three days after operation. On the first postoperative day CD scans revealed that the ossification has been fully removed and the spinal cord has been completely decompressed. For the whole 71 patients, no catastrophic complications, such as major vascular injury, spinal cord injury, or pleural effusion formation occurred during surgery.

The CT result on the first postoperative day confirmed that the ossification was completely resected and that spinal cord decompression was sufficient. The bone structure can be selectively removed without damaging the adjacent nerve tissue, due to the precise oscillations of the ultrasonic blade. Combined with careful removal of the lamina with the use of osteotome and towel clamps mentioned above, the low operation time, low blood loss, low complication rate was achieved.

In conclusion, based on the result of the current study, ultrasonic osteotome combined with conventional osteotome to resect the lamina for laminectomy has been shown as an effective, safe, and feasible option for the treatment of thoracic ossification of the ligamentum flavum.