General
- An ultra-minimally invasive technique designed to treat symptomatic central lumbar canal stenosis caused by ligamentum flavum hypertrophy. It aims to increase the spinal canal's diameter by performing a limited percutaneous laminotomy and thinning the ligamentum flavum.
Technique
- Pre-procedural Setup
- Anesthesia:
- The procedure is performed under local anesthesia and monitored anesthesia care (MAC), allowing for an outpatient experience and rapid recovery.
- Positioning:
- The patient is placed in the prone position with a bolster to facilitate the opening of the spinal anatomy. Positioning is critical to reduce lumbar lordosis and any body axis tilt.
- Imaging
- Imaging Guidance:
- C-arm fluoroscopy is used throughout.
- The contralateral oblique view is the primary working view, providing the thickest visualization of the lamina to create a safe posterior working zone. An anterior/posterior view is used to verify medial/lateral positioning.
- Epidurography:
- The process begins with an epidurogram using myelographically compatible contrast to visualize the working zone and assess the level of decompression achieved.
- Surgical Access
- Incision:
- Access is gained through a single 6-gauge portal site via a small "stab wound" incision.
- Portal Placement:
- A guiding portal and inner trocar are inserted percutaneously, lateral to the spinous process, and advanced to the inferior vertebral segment lamina toward the interlaminar space under direct fluoroscopic guidance.
- Stability:
- A Back Plate and Accessory Guide are used to secure the portal against the skin and limit the forward motion of the working instruments.
- Decompression Steps
- Bone Sculpting:
- A specialized Bone Sculpter Rongeur is advanced to the free edge of the lamina. The surgeon rotates the device to precisely remove small pieces of both the superior and inferior lamina, performing a limited laminotomy.
- Tissue Sculpting:
- After clearing the interlaminar space, a Tissue Sculpter is advanced under the lamina into the dorsal aspect of the hypertrophic ligamentum flavum. A specially designed tip debulks the ligament by removing its posterior portion.
- Verification:
- Decompression is confirmed by observing changes in the epidurogram; success is indicated when contrast flows more easily into a larger and straighter epidural area.
- Bilateral Treatment:
- If necessary, the entire process can be repeated on the opposite side of the spinous process to achieve bilateral decompression of the central canal.
Advantages
- Superior Safety Profile:
- A survey of 90 consecutive patients reported no major adverse events or complications related to the devices or the procedure.
- There were no reported incidents of dural punctures or tears, which occur in 5.8% to 15.6% of other open and minimally invasive surgeries.
- The procedure resulted in no blood transfusions, nerve injuries, or epidural hematomas, further reducing the complexity of perioperative care.
- Reduced Patient Trauma and Rapid Recovery:
- The technique utilizes a single 6-gauge portal site (a small "stab wound" incision), which results in less tissue trauma.
- It is performed as an outpatient treatment, allowing patients to be discharged home after a short period of observation.
- Avoidance of General Anesthesia:
- The procedure can be conducted under a combination of local anesthetic and monitored anesthesia care (MAC), making it a viable option for patients who may be high-risk for general anesthesia.
- Preservation of Spinal Integrity:
- Decompression is achieved without the need for fixation/stabilization devices, implants, or spacers.
- Cost-Effectiveness:
- The procedure offers a potential reduction in healthcare costs compared to more extensive surgical procedures or comprehensive medical management.
Disadvantages
- Narrow Therapeutic Focus:
- The devices are specifically designed to resect thickened ligamentum flavum and small areas of bone; they are currently contraindicated for disc procedures.
- The tools are not intended to be used near lateral neural elements, meaning they cannot address certain types of lateral or foraminal stenosis.
- Lack of Long-Term Efficacy Data in Initial Surveys:
- Anatomical Restrictions:
- Successful outcomes are highly dependent on the etiology of the stenosis being specifically hypertrophic ligamentum flavum.