General
- A technique for performing Total En Bloc Spondylectomy (TES) in the lumbar spine, designed to overcome the anatomical challenges of this region while maintaining the benefits of a single-stage posterior procedure.
- This technique, referred to as a posterior-only paraspinal approach, aims to provide a wider view of the ventral operative field compared to the traditional posterior midline approach, potentially reducing the risk of injury to the Inferior Vena Cava (IVC) and segmental vessels in the lumbar region.
- Pros
- Wider View:
- It provides a wider view of the ventral operative field, allowing for better visualization of the lateral margin of the lumbar vertebral body, the psoas major muscle, and the IVC.
- Vascular Safety:
- It facilitates safer completion of blunt dissection and ligation of segmental vessels, reducing the risk of vessel injury to the IVC and segmental vessels.
- Reduced Trauma:
- As a single-stage posterior approach, it results in shorter operative time and less blood loss compared to combined posteroanterior approaches for lumbar TES.
- Muscle Preservation:
- Because the exposure uses the anatomic intermuscular space, it may minimize ischemia and denervation of the paraspinal muscles, potentially allowing for faster functional recovery.
Indication
- A valid alternative for TES of lumbar spinal tumors (L2, L3, and L4 lesions were studied).
- Recommended for overweight or muscular patients.
- Tumor Type:
- It is suitable for lesions classified as Tomita types 1–4, where the anterior and lateral margins of the vertebral body are intact, minimizing the risk of vena cava injury during dissection along the bony surface.
Surgical technique
- Anesthesia and positioning
- Positioning: The patient is placed in a prone position under general anesthesia with electrophysiologic monitoring maintained throughout the operation.
- Incision and Dissection:
- A posterior midline incision is initially made over the spinous processes, extending two vertebrae above and two below the tumor segment.
- Paramedian fascial incisions are then made, typically located about one finger breadth lateral to the midline.
- The surgeon identifies the natural cleavage plane between muscle groups:
- Below L2: between the multifidus and longissimus muscles OR
- At L1–L2 level: between the longissimus muscles and iliocostalis lumborum muscles
- These muscles are split and retracted laterally using blunt finger dissection to expose the lateral aspects of the facet joints, pars, and pedicle.
- Midline Access for Laminectomy: Since the paraspinal incisions alone are insufficient for performing an en bloc laminectomy, a short midline incision is required over the tumor segment, allowing the paraspinal muscles to be dissected and retracted laterally for visualization of the posterior spinal bone structures.
- Instrumentation: Pedicle screws are inserted two vertebrae above and two below the tumor segment.
En Bloc Laminectomy
- This step is performed similarly to the standard posterior TES technique.
- The superior articular process of the tumor vertebra and the inferior articular processes of the neighboring vertebra are cut and removed.
- A C-shaped, curved malleable wire guide is introduced through the intervertebral foramen above the pedicle and passed out the intervertebral foramen below the pedicle.
- A wire saw is passed through the guide, looped around the pedicle, and manipulated beneath the superior articular and transverse processes.
- The pedicles are cut bilaterally using a reciprocating motion of the wire saw, and the entire posterior elements are removed en bloc.
- Temporary fixation rods are subsequently placed to maintain stability.
En Bloc Corpectomy
- Nerve and Vessel Management:
- The exiting nerve roots at the resection level and the level above are meticulously dissected from the pedicle to their insertion site into the psoas muscle. Lumbar nerve roots must be rigorously protected and cannot be sacrificed, unlike in the thoracic spine.
- The spinal branch of the segmental artery is identified, ligated, and divided.
- Anterior Dissection:
- Blunt dissection (using a peanut) is performed anteriorly along the plane between the lateral wall of the vertebral body and the psoas muscle, segmental artery, and exiting nerve roots.
- A Kerrison rongeur may be used to release the anterior border of the iliopsoas muscle from the vertebral body, as the muscle is posterior to the aorta and vena cava.
- Because direct finger dissection is challenging in the lumbar region due to the proximity of the great vessels, a large C-shaped aortic clamp with a small blunt tip is utilized.
- This clamp is slid closely around the upper-middle recess of the vertebral body (from the right side to the left) to fully separate the vertebral body from the great vessels (aorta and vena cava).
- Gauze is strategically placed around the vertebral body during the dissection to protect the surrounding vital tissues, particularly the great vessels.
- Anterior Osteotomy:
- A wire guide is introduced along the C-clamp to pass the wire saw.
- The wire saw is folded and passed back through the posterior one fourth of the disc space (just beneath the annulus) to create a "U" loop wire.
- This loop wire is used to excise the anterior part of the disc and the anterior longitudinal ligament.
- The remaining posterior disc tissue (posterior one fourth) is cut with a scalpel after the thecal sac has been separated from the venous plexus and the posterior longitudinal ligament.
- Removal of Vertebra: The freed anterior column is gently mobilized, rotated around the thecal sac, and removed laterally through the interspace between nerve roots.
Reconstruction:
- Ventral reconstruction is performed using a cylindrical cage (e.g., hydroxyapatite or titanium mesh) filled with bone graft material. The posterior instrumentation is then adjusted to slightly compress the inserted spacer.
Outcomes
- Data in a small sample of patients
- Mean operative time was 464 minutes (approx. 7.7 hours)
- Mean blood loss was 1280 mL
- Complications:
- CSF leak
- Transient motor weakness from nerve root traction
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