Transtubular Endoscopic Posterolateral Decompression for L5-S1 Lumbar Lateral Disc Herniation

Diagnosis and surgery for lumbar foraminal stenosis and lumbar lateral disc herniation at L5-S1 level is challenging to spinal surgeon because of its unique structure. Iliac crest below L5 transverse process, small space between sacral alar and L5 transverse process, and osteophytes make the operating window very narrow. If the bone resection is not enough, inadequate decompression to the L5 nerve root made the residual symptom.

Massive bone resection cause postoperative instability. These reason limit the surgeons familiarity with the extraforaminal L5 root decompression. Several reports supported good result with minimally invasive spine surgeries such as microscopic or endoscopic procedure at this area to decompress L5 nerve root.

Recently, the use of navigation for foraminal decompression of L5 nerve root has been reported with good surgical results. Truly endoscopic discectomy is getting popular to remove natural disc herniation. Furthermore, microendoscopic procedure in combination with navigation, can help the surgeon to decompress L5 nerve root precisely.

Usually, these techniques require intraoperative C-arm usage. The goal of this method is to decompress L5 root precisely with minimal bony resection without C-arm. This study was approved by the Ethics Committee of Okayama Rosai Hospital.

This is a protocol of transtubular endoscopic posterolateral decompression for L5-S1 lumbar lateral disc herniation. Evaluation of radiograms and magnetic resonance imaging. Perform anterior, posterior, and lateral radiography in standing position to check lumbar deformity and spondylolisthesis.

If the patient has severe deformity, spinal fusion is indicated. Perform functional radiography in standing position. Check functional radiograms to confirm lumbar instability by measuring vertebral abnormal movement.

Perform MRI to accurately assess lumbar disc herniation showing where a herniation has occurred, and which nerves are affected. For lateral lumbar disc herniation, take coronal T2-weighted image to identify the location of the herniated disc. Evaluation of CT and MRI-CT fusion image.

CT is important to check the herniated disc is calcified or to eliminate a nerve is compressed by the osteophyte. MRI-CT fusion image is very useful to understand the exact 3D location of herniated disc. Patient positioning and neuromonitoring.

Provide general anesthesia to the patient. Ensure that the patient's eyes are not compressed with special face cover. Pay attention to the bolster position not to compress the abdomen of the patient.

The neuromonitoring is preferable for this technique. Our system is a multimodality intraoperative motoring system, use to access spinal cord integrity and provide warning potential harm to critical neural pathways. Intraoperative CT and spinal navigation.

This computer-controlled flexible full carbon frame is very useful. Transmit the CT 3D reconstructed images to the navigation system automatically by a cable. Navigated instrument registration.

Register the navigated pointer director and high-speed burrs by tapping the tip of the different frame hold by manual. Incision and muscle dissection. With the help of a navigated pointer, confirm the location of L5-S1 foraminal level.

Make an approximately 2 centimeter longitudinal skin incision. Then dissect the subcutaneous tissue, lumbar iliocostalis, and multifidus muscle along muscle fibers. Doctor navigated fast director at the base of the L5 transverse process using the navigation.

Then insert the sequential dilators. Insert the final tube and fix it to the frame. Fix the final tube to the flexible arm assembly primary.

Bone resection with navigated high-speed burr. Check the L5-S1 level with the navigated pointer in the navigation monitor. Remove the bone at the base of transverse process and the lateral part of the facet joint with the navigated high-speed burr.

Endoscopic disc resection. Identify the L5 nerve root and retract cranially via nerve retractor. Then remove the disc fragment by pituitary forceps carefully.

These are the postoperative CT and MRI. Herniated disc and osteophyte are completely removed. Representative results.

There are eight cases, four men and four women of this new technique. Average age was 72 years old, and the average follow-up period was 1.5 years. Average surgical time and blood loss were 143 minutes and 134 milliliter, respectively.

The average recovery rate of Japanese Association score was 72.3 percentage. There was no surgical complication. In conclusion, our new technique of navigating decompression is very useful to natural L5-S1 lesion.

O-arm navigation gives the surgeons 3D image guidance and helps in accurate development of bony elements. Minimum facet resection avoids additional postoperative spinal instability, especially the use of navigated burr, helps real-time dynamic feedback during resection of bony spur. Thank you for your attention.