A retrospective analysis was performed on 26 patients with lumbar posterior apophyseal ring separation treated by UBE technique and followed up for more than 6 months in the author's hospital from June 2020 to September 2021.The inclusion criteria were as follows:(1) Imaging examination (CT and MRI) confirmed lumbar disc herniation with posterior apophyseal ring separation, the symptoms and signs were consistent with imaging and the responsible segments were single;(2)Neurogenic claudication or radicular leg pain with or without back pain;(3)Conservative treatment is poor or recurrent attacks;(4)The suffer received unilateral biportal endoscopic decompression.
Exclusion criteria were as follows:(1)segmental instability; (2)lumbar spinal stenosis; (3)lumbar spondylolisthesis;(4)surgery history of targeted segment;(5)infectious history of lumbar spine.
The study was approved by our institutional review board and the informed consent was obtained from all patients.
All procedures were performed by single surgeon. After induction of general anesthesia, patients were positioned prone with the abdomen free and the spine flexed to open the interlaminar space.
Placement of endoscopic portals
After level confirmation was conducted under the C-arm fluoroscopic guidance, two portals were made 1cm parallel to midline of spinous process and 1.0cm above and 1.0cm below the center of the target level. The proximal portal is about 6mm to introduce the arthroscope and the distal portal is about 10mm to place the surgical instruments. The fascia perpendicular to the skin is incised to prevent the obstruction of water flow during surgery.The distance between both portals allows the surgeon to perform the triangulation technique with complete freedom of the surgical tool. The primary dilator is then inserted into the two portals through the paraspinal muscles without any separation till it is docked over the lamina surface and then it is uesd to separate bluntly and pushed aside the overlying soft tissue step by step to form the a visual surgical field.
Insertion of the endoscope and preparation of the surgical field
The endoscopic cannula and trochar are introduced through the endoscopic portal till they are docked over the superior lamina.The irrigation fluid is initiated and the trochar is removed to wash out the blood and then the endoscopy is introduced through the cannula. The irrigation fluid used is isotonic saline to avoid tissue edema.Then the radiofrequency probes and arthroscopic shavers are used to clean the remaining soft tissues or muscles over the lamina and ligamentum flavum.
Laminotomy and ligamentum flavum removal
When the ligamentum flavum of the target interlaminar space and partial lower lamina of superior lamina are completely exposed, the arthroscopic shaver is used to thin out ispilateral lamina, which was followed by laminectomy by Kerrison punch to complete a laminotomy and medial facetectomy until the upper edge of deep part of ligamentum flavum is free. After ensuring that the plane between ligamentum flavum and dura is free from adhesion, the ligament is peeled down in caucal direction and is removed using the Kerrison rongeour.
After identification of the nerve root adjacent to the dural sac, the spinal canal is explored according to direction of nucleus pulposus herniation. According to the needs, forceps or drill are used to enlarge lamina window. If the lateral recess decompression is required, we prefer to undercut the facet down to the medial wall of the pedicle.However, attention should be paid to protect the facet joint structure to avoid excessive damage to the stable spinal structure. After the herniated nucleus pulposus is found, the adhesions between the nucleus pulposus and the surrounding soft tissue is separated by a probe. After operation assistant retracted dural sac or nerve root using an L-type nerve retractor through the working portals,the surgeon uses forceps to remove the herniated nucleus pulposus. We prefer to used Kerrison rongeour to remove the posterior margin of the ossification.It is not necessary to remove the ossification completely to avoid retract the nerve excessively.
Then the surgeon need to adjust the working position and explore the targeted intervertebral space. Annulotomy could be performed using a microknife if it is required. This is followed by discectomy and pituitary forceps and curettes were used to remove any remnant fragments of the herniated disc.The procedure was completed after conforming the decompression status and freely moving traversing root.
The endoscopy and instruments are moved and remaining fluid is discharged by squeezing the skin around the portals. A drainage tube is placed in all patients through the working portal to prevent hematoma formation, followed by wound closure.
Operation time,length of postoperative hospital stay and complications were recorded. The clinical efficacy was evaluated by Visual Analogue Scale (VAS), Oswestry Disability Index (ODI) and modified Macnab scale at preoperative, postoperative 1, 3, 6months and the last follow-up.
Data were statistically described in terms of mean±standard deviation (±SD), or frequencies (number of cases) and percentages when appropriate. We conducted general linear model with repeated measures to analyze the clinical efficacy before the procedure and at the follow-up and we compared periodic outcomes using Student t test. p values <0.05 were considered
statistically significant. We used SPSS 22.0(Statistical Package for the Social Science; SPSS Inc., Chicago, IL, USA ) for statistical analysis.