Percutaneous Endoscopic Transforaminal Discectomy with Foraminoplasty in the Treatment of L4-L5 and L5-S1 Disc Herniation: A Minimum 1-year Follow-up Study.

Background The anatomic and biomechanical aspects of the L5-S1 level present unique operative challenges compared with the L4-L5 level. We aim to explore the clinical outcomes and radiographic measurements of L4-L5 patients compared with L5-S1 patients after undergoing Percutaneous Endoscopic Transforaminal Discectomy with Foraminoplasty (PETDF). Methods A total of 84 patients who underwent PETDF for LDH treatment between January 2017 and June 2020 were included in this study. Preoperative, perioperative, demographic data, clinical and radiographic outcomes were compared between patients with L4-L5 involvement and patients with L5-S1 involvement. Results There were no significant differences between the two groups in terms of Age, Gender, Follow-up time, the postoperative questionnaire results (Visual Analog Scale [leg], VAS [lower back], and Oswestry Disability Index) or the Excellence and Good Rate and Recurrence Rate. There was no significant difference in the mean preoperative to postoperative change in Intervertebral Space Height (ISH), Intervertebral Space Angle (ISA), Lumbar Lordosis, Foraminal Area (FA) of Operating Side and FA of Contralateral Side between the 2 groups. The mean VAS of Leg Pain, VAS of Lower Back Pain and ODI postoperative scores were significantly improved over the preoperative scores in each of the two groups and the ISH, ISA, FA of Operating Side and FA of Contralateral Side postoperative were significant difference form preoperative Conclusion PETDF is an effective and safe treatment approach for lumbar disc herniation in both L4/L5 and L5/S1 level. Although it may increase lumbar ISA and result in low CFA (contralateral foraminal area) and ISH.

Three-Dimensional Volumetric Changes and Clinical Outcomes after Decompression with DIAM™ Implantation in Patients with Degenerative Lumbar Spine Diseases

Background and objectives: The prevalence of degenerative lumbar spine diseases has increased. In addition to standard lumbar decompression and/or fusion techniques, implantation of interspinous process devices (IPDs) can provide clinical benefits in highly selected patients. However, changes in spinal structures after IPD implantation using magnetic resonance imaging (MRI) have rarely been discussed. This volumetric study aimed to evaluate the effect of IPD implantation on the intervertebral disc and foramen using three-dimensional assessment. Materials and Methods: We retrospectively reviewed patients with lumbar degenerative disc diseases treated with IPD implantation and foraminotomy and/or discectomy between January 2016 and December 2019. The mean follow-up period was 13.6 months. The perioperative lumbar MRI data were processed for 3D-volumetric analysis. Clinical outcomes, including the Prolo scale and visual analog scale (VAS) scores, and radiographic outcomes, such as the disc height, foraminal area, and translation, were analyzed. Results: Fifty patients were included in our study. At the one-year follow-up, the VAS and Prolo scale scores significantly improved (both p < 0.001). The disc height and foraminal area on radiographs also increased significantly, but with limited effects up to three months postoperatively. MRI revealed an increased postoperative disc height with a mean difference of 0.5 ± 0.1 mm (p < 0.001). Although the mean disc volume difference did not significantly increase, the mean foraminal volume difference was 0.4 ± 0.16 mm3 (p < 0.05). Conclusions: In select patients with degenerative disc diseases or lumbar spinal stenosis, the intervertebral foramen was enlarged, and disc loading was reduced after IPD implantation with decompression surgery. The 3D findings were compatible with the clinical benefits.

Compressive Biomechanics of the Reptilian Intervertebral Joint

This study compared the pre-sacral intervertebral joints of the American alligator (Alligator mississippiensis) with those from specimens of Varanus. These two taxa were chosen because they have similar number of pre-sacral vertebrae and similar body weights; however, Varanus can move bipedally and has diarthrotic intervertebral joints, whereas Alligator has intervertebral discs and cannot move bipedally. This study consisted of three objectives; 1) to document the anatomy of the intervertebral joint, 2) to quantify the compressive biomechanics of the intervertebral joints and explore which features contributed to compression resistance, and 3) to quantify the impact of compression on the intervertebral foramen and spinal nerves in these two taxa. The experimental results revealed that the diarthrotic intervertebral joints of Varanus were significantly (4x) stiffer than the intervertebral disc of Alligator, and that a significant component of this increased stiffness arose from the facet joints. Compressing the intervertebral joints of the two taxa caused a reduction in foraminal area, but the magnitude of this reduction was not significantly different. We hypothesize that the main factor preventing spinal nerve impingement in Varanus during gravitational compression is the relatively small size of the spinal ganglion/nerve relative to the foraminal area.

Predicting Unilateral Post-laminectomy C5 Palsy by Measuring C5 Exit Foramen Area on Preoperative Computed Tomography

Background and aim: Postoperative C5 motor palsy is known as a common complication, not only after cervical laminectomy but also after anterior discectomy. There is no consensus on any of the proposed mechanisms of C5 palsy following posterior cervical decompression. It was found that C5 palsy is more common in patients with smaller C5 root foramen area. The purpose of this study was to define a cut-off value for C4-C5 foraminal area on preoperative computed tomography images to predict post-laminectomy C5 palsy. Methods and Materials/Patients: In this prospective clinical study, C4-C5 foraminal area of 119 patients with cervical spondylotic myelopathy calculated on reformatted pure sagittal computed tomography images value was defined by measuring maximal height and transverse diameter of foramina and a cut-off in which with lesser amounts, post-laminectomy C5 palsy was more common. Results: Of 119 patients with spondylotic myelopathy undergoing cervical laminectomy,23 ones experienced postoperative C5 palsy with mean C4-C5 foraminal area of 44.54±0.72 mm2.Mean C5 root exit foraminal area in patients with intact post-operative root function was calculated 56.78±5.48 mm2 and the difference between these two groups was statistically significant (P<0.05). No patient with C5 exit foraminal area more than 46 mm2had C5 palsy after laminectomy. Conclusion: The incidence of post-laminectomy C5 palsy is significantly higher in patients with C5 exit foraminal area less than 46 mm2. Prophylactic C4-C5 foraminotomy in this group may significantly reduce the risk of postoperative C5 nerve motor palsy, although the effect of this procedure is still debatable.

Changes in foraminal area with anterior decompression versus keyhole foraminotomy in the cervical spine: a biomechanical investigation

OBJECTIVEAnterior cervical discectomy and fusion (ACDF) with or without partial uncovertebral joint resection (UVR) and posterior keyhole foraminotomy are established operative procedures to treat cervical disc degeneration and radiculopathy. Studies have demonstrated reliable results with each procedure, but none have compared the change in neuroforaminal area between indirect and direct decompression techniques. The purpose of this study was to determine which cervical decompression method most consistently increases neuroforaminal area and how that area is affected by neck position.METHODSEight human cervical functional spinal units (4 each of C5–6 and C6–7) underwent sequential decompression. Each level received the following surgical treatment: bilateral foraminotomy, ACDF, ACDF + partial UVR, and foraminotomy + ACDF. Multidirectional pure moment flexibility testing combined with 3D C-arm imaging was performed after each procedure to measure the minimum cross-sectional area of each foramen in 3 different neck positions: neutral, flexion, and extension.RESULTSNeuroforaminal area increased significantly with foraminotomy versus intact in all positions. These area measurements did not change in the ACDF group through flexion-extension. A significant decrease in area was observed for ACDF in extension (40 mm2) versus neutral (55 mm2). Foraminotomy + ACDF did not significantly increase area compared with foraminotomy in any position. The UVR procedure did not produce any changes in area through flexion-extension.CONCLUSIONSAll procedures increased neuroforaminal area. Foraminotomy and foraminotomy + ACDF produced the greatest increase in area and also maintained the area in extension more than anterior-only procedures. The UVR procedure did not significantly alter the area compared with ACDF alone. With a stable cervical spine, foraminotomy may be preferable to directly decompress the neuroforamen; however, ACDF continues to play an important role for indirect decompression and decompression of more centrally located herniated discs. These findings pertain to bony stenosis of the neuroforamen and may not apply to soft disc herniation. The key points of this study are as follows. Both ACDF and foraminotomy increase the foraminal space. Foraminotomy was most successful in maintaining these increases during neck motion. Partial UVR was not a significant improvement over ACDF alone. Foraminotomy may be more efficient at decompressing the neuroforamen. Results should be taken into consideration only with stable spines.

Morphometric Changes of the Lumbar Intervertebral Foramen after Percutaneous Endoscopic Foraminoplasty under Local Anesthesia

Background Percutaneous endoscopic diskectomy (PED) for the lumbar spine is a relatively new technique that is becoming more common due to its relatively less invasive nature. However, one possible serious complication is an exiting nerve injury when the cannula of the endoscope is inserted into the neural canal through the intervertebral foramen. A technique to enlarge the intervertebral foramen, called foraminoplasty, was recently established to insert the cannula safely into an appropriate position in the neural canal. Methods In this study we performed foraminoplasty during PED under local anesthesia on 15 patients. Using computed tomography scans before and after surgery, the morphometric changes of the intervertebral foramen were evaluated. Surgery-related complications were reviewed. Results There were 13 men and 2 women, 21 to 86 years of age (mean: 47.1 years). Disk levels were 13 cases at L4–L5, one case at L3–L4, and one case at L5–S1. In 50% of the cases, the mean foraminal area significantly increased from 58.6 mm2 before surgery to 88.4 mm2 after surgery (p < 0.05 by paired t test). The diameter of the foramen was increased at all three points: the lower end plate of the superior vertebrae, the disk, and the upper end plate of the inferior vertebrae. The area increased ∼ 1.5 times, especially at the upper end plate of the inferior vertebrae. In all cases, no exiting nerve injury was encountered during PED. Conclusion Foraminoplasty was an effective method for avoiding exiting nerve root injury during transforaminal PED.