Facet Joint Preservation Research Articles

Comparative study between unilateral biportal endoscopic discectomy and percutaneous interlaminar endoscopic discectomy for the treatment of L5/S1 disc herniation

To compare the clinical outcomes of unilateral biportal endoscopic discectomy (UBED) and percutaneous interlaminar endoscopic discectomy (PIED) for treating L5/S1 disc herniation. Patients with L5/S1 disc herniation treated with UBED (n=46) and PIED (n=50) in our hospital during the same period were retrospectively reviewed. Clinical outcome, radiographic parameters and complications of each group were collected and evaluated. The mean follow-up period was 14.11±3.47 months in UBED group, and 14.52±5.37 months in PIED group. There was no significant difference in VAS leg (P=0.836) or lumbar scores (P=0.335) between PIED and UBED group at preoperative, 1-day postoperative, and last follow-up point. Within the same group, there were significant differences in VAS leg (P<0.001) and lumbar scores (P<0.001) compared pairwise at three time points. ODI scores of both groups showed significant improvement at the last follow-up (P<0.001) (P<0.001). And there was no significant difference in patient satisfaction rates (97.8% vs 96%) between two groups based on MacNab criteria. The percentage of facet joint preservation was 96.74±9.10% in UBED group, and 99.22±1.52% in PIED group. The total blood loss and hospitalization cost was more in the UBED Group. One patient in both groups showed postoperative hematoma. A dural tear occurred in UBED group and a never root injury occurred in PIED group. UBED indicates similar short-term efficacy compared with PIED for treating L5/S1 disc herniation. No difference was found in facet joint preservation between two groups. The increased cost of UBED due to surgical consumables is believed to be resolved in the future.

Effect of Facet Joint Resection on Postoperative Radiographic and Clinical Outcomes After Microendoscopic Laminectomy for Single-Level Lumbar Spinal Stenosis

Facet joint destruction causes postoperative spinal instability, resulting in poor clinical outcomes after lumbar decompression surgery. However, the effect of facet joint destruction on radiographic and clinical outcomes after microendoscopic laminectomy (MEL) is unknown. Therefore, the current study aimed to examine the effect of facet joint resection on radiographic and clinical outcomes after single-level MEL surgery. This study included 116 patients with lumbar spinal canal stenosis (LSCS) who underwent single-level (L4/5) MEL surgery. Eligible patients were divided into the following groups: group P (facet joint preservation rate= 100%) (n= 70); group PR (50%≤the facet joint preservation rate <100%) (n= 27); and group R (the facet joint preservation rate <50%) (n= 19). The demographic characteristics of the patients, surgical data, preoperative and 1-year postoperative radiographic measurements, and clinical outcomes were compared among the 3 groups. Moreover, preoperative and postoperative radiographic and clinical outcomes were compared after adjusting the demographic characteristics of the patients and surgical data by the inverse probability weighting method with propensity scores. The 3 unweighted groups did not significantly differ in terms of demographic characteristics, surgical data, and preoperative and postoperative radiographic and clinical outcomes. Even after adjusting for the demographic characteristics and surgical data, the preoperative and postoperative radiographic and clinical outcomes were comparable among the 3 weighted groups. The extent of facet joint resection might have a minimal impact on radiographic and clinical outcomes at 1 year after single-level MEL surgery.

Role of unilateral partial facet joint preservation in postero-lateral approach lumbar interbody fusion for patients with degenerative lumbar spinal stenosis presenting bilateral lower limb symptoms: a retrospective study

BackgroundPosterolateral decompression and fusion with internal fixation is a commonly used surgical approach for treating degenerative lumbar spinal stenosis (DLSS). This study aims to evaluate the impact of preserving a portion of the unilateral facet joint during decompression on surgical outcomes and long-term recovery in patients.MethodsThis study analyzed 73 patients with DLSS accompanied by bilateral lower limb neurological symptoms who underwent single-level L4/5 posterolateral decompression and fusion surgery from January 2022 to March 2023. Patients were categorized into two groups based on the type of surgery received: Group A comprised 31 patients who underwent neural decompression without facet joint preservation, while Group B consisted of 42 patients who underwent neural decompression with preservation of partial facet joints on one side. Regular follow-up evaluations were conducted, including clinical and radiological assessments immediately postoperatively, and at 3 and 12 months thereafter. Key patient information was documented through retrospective chart reviews.ResultsMost patients in both groups experienced favorable surgical outcomes. However, four cases encountered complications. Notably, during follow-up, Group B demonstrated superior 1-year postoperative interbody fusion outcomes (P < 0.05), along with a trend towards less interbody cage subsidence and slower postoperative intervertebral disc height loss. Additionally, Group B showed significantly reduced postoperative hospital stay (P < 0.05).ConclusionUnder strict adherence to surgical indications, the posterior lateral lumbar fusion surgery, which preserves partial facet joint unilaterally during neural decompression, can offer greater benefits to patients.

Influence of facetectomy, cross-link augmentation, and interbody procedure on progression of bone fusion in single-level posterior lumbar interbody fusion using the long cortical bone trajectory technique.

When using the cortical bone trajectory (CBT) technique, two technical countermeasures are recommended to promote bone fusion: taking a long CBT screw path directed more anteriorly and improving the stability of the spinal construct by facet joint preservation, cross-link augmentation, and rigid anterior interbody reconstruction. However, there has been no report on how these surgical procedures, which are heavily dependent on the surgeon's preference, contribute to successful bone fusion. The aim of the present study was to investigate the progression of lumbar spinal fusion using the long CBT technique and identify factors contributing to the time taken to achieve bone fusion, with a particular focus on the involvement of surgical procedures. A total of 167 consecutive patients with L4 degenerative spondylolisthesis who underwent single-level posterior lumbar interbody fusion at L4-5 using the long CBT technique were included (mean follow-up 42.8 months). Bone fusion was assessed to identify factors contributing to the time to achieve bone fusion. Investigated factors were 1) age, 2) sex, 3) BMI, 4) bone mineral density, 5) intervertebral mobility, 6) screw depth in the vertebra, 7) extent of facetectomy, 8) cross-link augmentation, 9) cage material, 10) cage design, 11) number of cages, and 12) contact area of cages with the vertebral endplate. The bone fusion rate was 89.2% at 2 years postoperatively and 95.8% at the last follow-up, with a mean period to bone fusion of 16.6 ± 9.6 months. Multivariate regression analysis revealed that age (standardized regression coefficient [β] = 0.25, p = 0.002), female sex (β = -0.22, p = 0.004), and BMI (β = 0.15, p = 0.045) were significant independent factors affecting the time to achieve bone fusion. There was no significant effect of surgical procedures (p ≥ 0.364). This is the first study to investigate the progression of lumbar spinal fusion using the long CBT technique and identify factors contributing to the time taken to achieve bone fusion. Patient factors such as age, sex, and BMI affected the progression of bone fusion, and surgical factors had only weak effects.

Preliminary Clinical and Radiological Outcomes of the "No-Punch" Decompression Techniques for Unilateral Biportal Endoscopic Spine Surgery.

To avoid the most offending surgical instrument for dural tears, we develop a "no-punch" decompression technique for unilateral biportal endoscopic (UBE) spine surgery. This retrospective study enrolled 68 consecutive patients with degenerative lumbar spinal stenosis segments. The treatment results were evaluated using the visual analogue scale (VAS) for low back and leg pain, the Japanese Orthopaedic Association (JOA) scores, and the Oswestry Disability Index (ODI). Radiological outcomes were evaluated using the preoperative and postoperative magnetic resonance imaging. This study included 36 male and 32 female patients who received 109 segments of decompression, with an average age of 68.7 (37-90 years). The average operation time was 52.2 minutes. The average hospital stay was 3.1 days. There were no dural tears but 3 minor surgical complications, all treated conservatively. The VAS for low back and leg pain improved from 4.6 and 7.0 to 0.8 and 1.2. The JOA score improved from 16.2 to 26.8, with an improvement rate of 82.0%. The ODI improved from 50.1 to 18.7. All these improvements were statistically significant. The cross-sectional dural area improved from 61.1 to 151.3 mm2, with an average increase of 90.2 mm2 and 205.3%. 87.1% of the ipsilateral facet joints and 84.7% of the contralateral facet joints were preserved. In 61% of the decompressed segments, the ipsilateral facet joints were preserved better than the contralateral facet joints. The UBE "no-punch" decompression technique effectively avoids the dural tears. It provides effective neural decompression, excellent facet joint preservation, and good treatment outcomes.

Early Clinical and Radiologic Evaluation of Unilateral Biportal Endoscopic Unilateral Laminotomy and Bilateral Decompression in Degenerative Lumbar Spinal Stenosis: A Retrospective Study.

The aim of this study is to evaluate the changes in radiologic parameters and clinical outcomes following unilateral biportal endoscopic unilateral laminotomy and bilateral decompression (UBE ULBD) for treatment of central lumbar spinal stenosis. Forty-one central lumbar spinal stenosis patients who underwent UBE ULBD were enrolled from April 2021 to February 2023. Visual analog scale (VAS) for back pain and leg pain, Oswestry Disability Index (ODI) score, and the modified MacNab criteria were assessed preoperatively and postoperatively. The preoperative and postoperative cross-sectional area of the spinal canal (CSAC), anteroposterior diameter, horizontal width, and ipsilateral and contralateral lateral recess height were calculated from axial computed tomography (CT) scans. Percentage of facet joint preservation measured on axial CT scans was obtained preoperation and postoperation. The VAS for back and leg pain improved from 7.24 ± 0.80 and 7.59 ± 0.59 preoperatively to 2.41 ± 0.55 and 2.37 ± 0.62 (p < 0.05) postoperatively and 1.37 ± 0.54 and 1.51 ± 0.55 at the last follow-up (p < 0.05). For ODI, improvement from 60.37 ± 4.44 preoperatively to 18.90 ± 4.66 (p < 0.05) at the last follow-up was observed. CT scans demonstrated that the postoperative CSAC increased significantly from 287.84 ± 87.81 to 232.97 ± 88.42 mm (p < 0.05). The mean postoperative anteroposterior diameter and horizontal width increased significantly from 18.01 ± 3.13 and 19.57 ± 3.80 to 22.19 ± 4.56 and 21.04 ± 3.72 mm, respectively (p < 0.05). The ipsilateral lateral recess height and contralateral lateral recess height were 3.39 ± 1.12 and 3.20 ± 1.14 mm preoperatively and 4.03 ± 1.37 and 3.83 ± 1.32 mm (p < 0.05) postoperatively, with significant differences. The ipsilateral and contralateral facet joint preservations were 88.17 and 93.18%, respectively. The UBE ULBD surgery is a safe and effective treatment for central lumbar spinal stenosis, associated with significant improvement in clinical outcomes and radiologic parameters. Studies with larger samples and longer follow-up periods are needed for further research.

Finite element mechanical analysis of ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery

BackgroundUnilateral bilateral endoscopic spine surgery (UBE) is often performed to treat lumbar spinal stenosis and disc herniation. It has become a prominent method in endoscopic spine surgery because of its very low learning curve and broader operative field of vision. Currently, the ipsilateral approach and contralateral approach have been established for disc herniation in the foraminal area, intervertebral foramen region, or pedicle region. The contralateral method offers many benefits over the ipsilateral approach, including less bone labour during microsurgical decompression and the preservation of facet joints. However, because it uses the interlaminar window approach, it inevitably involves osteotomy of the patient’s superior and inferior articular processes, which may result in corresponding deterioration in the spine’s biomechanical stability and subsequent adjacent facet joint diseases caused by facet joint degeneration postoperatively.ObjectiveAs a result, the purpose of this work is to use a finite element model to evaluate how the ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery affect spinal stability while treating identical intervertebral disc herniation.Study designIn this study, a three-dimensional lumbar-sacral spine model was built and verified. Osteotomies were conducted for armpit-type lumbar disc herniation (LDH), periradicular-type LDH, and shoulder-type LDH. Postoperative lumbar spine models of the ipsilateral approach and contralateral approach in unilateral bilateral endoscopic spine surgery were developed. The von Mises stress on the endplate, shear force on the annulus fibrosus, pressure inside the intervertebral disc, and range of motion (ROM) of the L3 segment were all determined. The results of our well-validated model showed that osteotomy done in the ipsilateral approach deteriorated most biomechanical metrics.ResultsIn the majority of loading conditions, the contralateral approach caused the intervertebral disc’s biomechanical properties to increase, and the ipsilateral approach caused the intervertebral disc’s biomechanical properties to increase sharply more than the contralateral approach.ConclusionThe contralateral approach, which is now extensively employed in unilateral bilateral endoscopic spine surgery, may be regarded as an ideal surgical alternative for treating lumbar disc herniation without producing iatrogenic instability. This approach has a low facet joint reduction rate, minimum soft tissue injury, and precisely identifies the midline of the central spinal canal during the retraction of the thecal sac and nerve roots.

Saving Stabilizing Structure Treatment With Bilateral-Contralateral Decompression for Spinal Stenosis in Degenerative Spondylolisthesis Using Unilateral Biportal Endoscopy.

This study aimed to evaluate the treatment of spinal stenosis with spondylolisthesis using bilateral-contralateral unilateral biportal endoscopic (UBE) decompression to minimize facet joint damage. We retrospectively evaluated 42 patients with grade 1 spondylolisthesis who underwent bilateral-contralateral UBE decompression between July 2018 and September 2019. To identify segmental instability, static and dynamic images from preoperative and postoperative procedures and final follow-up radiographs were reviewed. Lateral radiograph slippage ratio, sagittal motion, and facet joint preservation were evaluated. Clinical assessments were conducted using the visual analogue scale (VAS), Oswestry Disability Index (ODI), and modified MacNab criteria. The average final follow-up period was 26.5 ± 1.3 months. The average preoperative slip percentage was 15.70% ± 5.25%, which worsened to 18.80% ± 5.41% at the final follow-up (p < 0.005). The facet joint preservation rate was 95.6% ± 4.1% on the contralateral side. Improvements in the VAS scores (leg pain: from 7.9 ± 2.2 to 3.1 ± 0.7; p < 0.005; back pain: from 7.2 ± 3.0 to 2.8 ± 1.0; p < 0.005) were observed at the final follow-up. The mean preoperative ODI was 26.19 ± 3.42, which improved to 9.6 ± 1.0 (p < 0.005). Thirteen patients exhibited delayed focal segmental instability following decompression. Despite the absence of symptoms or improvement with conservative treatment in the majority of patients with delayed instability, two patients required fusion surgery to address the instability. Additionally, 2 patients developed facet synovial cysts, while 2 experienced spinous process fractures. Bilateral decompression with a contralateral UBE approach could be an effective and alternative treatment method to reduce instability in spinal stenosis with grade 1 spondylolisthesis.

Biomechanical Effects of Facet Joint Violation after Single-level Lumbar Fusion with Transpedicular Screw and Rod Instrumentation.

In vitro biomechanical study. This study aimed to investigate the biomechanical effects of facet joint violation (FV) on mobility and optically tracked intervertebral disc (IVD) surface strains at the upper level adjacent to L4-5 pedicle screw-rod fixation. FV is a complication that can occur when placing lumbar pedicle screws; the reported incidence is as high as 50%. However, little is known about how FV affects superior adjacent-level spinal stability, and especially IVD strain, after lumbar fusion. Fourteen cadaveric L3-S1 specimens underwent L4-5 pedicle-rod fixation, 7 in the facet joint preservation (FP) group and 7 in the FV group. Specimens were tested multidirectionally under pure moment loading (7.5 Nm). Colored maps of maximum (ε1) and minimum (ε2) principal surface strain changes on the lateral L3-4 disc were generated with the surface divided into 4 quarters anterior to posterior (Q1, Q2, Q3, and Q4, respectively) for subregional analyses. Range of motion (ROM) and IVD strain were normalized to intact upper adjacent-level and compared between the groups using analysis of variance. Statistical significance was set at P <0.05. Normalized ROM was significantly greater with FV versus FP in flexion (11% greater; P =0.04), right lateral bending (16% greater; P =0.03), and right axial rotation (23% greater; P =0.04). Normalized L3-4 IVD ε1 during right lateral bending was greater on average for the FV group than the FP group: Q1, 18% greater; Q2, 12% greater; Q3, 40% greater ( P <0.001); Q4, 9% greater. Normalized ε2 values during left axial rotation were greater in the FV group, the highest increase being 25% in Q3 ( P =0.02). Facet joint violation during single-level pedicle screw-rod fixation was associated with increased superior adjacent level mobility and alteration of disc surface strains, with significant increases in selected regions and directions of loading.

Comparative Analysis With Modified Inclined Technique for Posterior Endoscopic Cervical Foraminotomy in Treating Cervical Osseous Foraminal Stenosis: Radiological and Midterm Clinical Outcomes.

ObjectiveWe compared the midterm clinical and radiological outcomes between 2 types of full endoscopic posterior cervical foraminotomy, including conventional posterior endoscopic cervical foraminotomy (PECF) and modified inclined technique for PECF. MethodsOne of the 2 types of PECF surgery was performed for defined cervical foraminal stenosis. The foraminal expansion ratio and facet resection rate and foraminal stenosis grade were measured using magnetic resonance imaging. Visual analogue scale (VAS) scores for neck and arm pain, neck disability index, MacNab criteria, operation time, hospital stay, and complications, including postoperative dysesthesia, were assessed. Clinical and radiological parameters were compared between the 2 surgical groups. ResultsThere were 49 and 46 patients in the PECF and modified-PECF groups, respectively. The modified-PECF group showed significantly higher expansion of distal foraminal diameter and foraminal height, and a lower facet resection rate compared to PECF group (in all, p<0.001). The modified-PECF group displayed significantly lower VAS score for neck pain at 1 day and 1 week after surgery and lower arm pain VAS score after 6-month follow-up (p=0.002, p=0.001, p=0.002, respectively). ConclusionCompared with the PECF, the modified inclined technique has radiologic benefits, including enhanced facet joint preservation, restoration of the natural course of nerve roots, and prevention of restenosis by expanding the superior articular process base, especially in grade 2 foraminal stenosis. Furthermore, the modified inclined technique significantly improved the postoperative VAS score for neck pain within the 1-week follow-up and that of arm pain after 6-month follow-up.

20. Biomechanical effect of facet joint violation on adjacent segment motion and disc strain following single level lumbar fusion with transpedicular screw and rod instrumentation

<h3>BACKGROUND CONTEXT</h3> Facet joint violation (FV) is a complication occurring while placing pedicle screws at the upper-most level using an entry point and trajectory too close to the superior facet joint. The incidence of FV has been reported up to be as high as 50%. However, little is known about how FV affects superior adjacent level spinal stability and especially intervertebral disc (IVD) strain after lumbar fusion. <h3>PURPOSE</h3> To investigate the biomechanical effects of FV in terms of mobility and disc surface strains at the upper level adjacent to L4-5 pedicle screw-rod fixation (PSR) in cadaveric specimens. The disc strain was studied with a new optical technique of soft tissue strain analysis (3D digital image correlation [DIC] technique). <h3>STUDY DESIGN/SETTING</h3> Biomechanic testing in human cadaveric spine specimens. <h3>PATIENT SAMPLE</h3> A total of 14 human cadaveric L3-S1 specimens. <h3>OUTCOME MEASURES</h3> 1. Upper adjacent segment range of motion. 2. Disc surface strain/stress. <h3>METHODS</h3> A total of 14 human cadaveric L3-S1 specimens were divided into two equal groups. L4-5 pedicle-rod fixation was performed in a different fashion in each group ie, facet joint preservation (FP) and facet joint violation (FV). The violation of the facet joint was defined by denuding the facet joint capsule and removing of the external cortical surface of the superior articular process with a 3 mm Leksell-rongeur. The entry point of these pedicle screws was located at the junction between the inferolateral aspect of the facet joint. All specimens were tested multi-directionally under pure moment loading (7.5Nm). DIC was performed with cameras positioned laterally (left side) to capture the change in principal disc strains (Pmax and Pmin) at the upper adjacent level (L3-4) under peak load. Optical motion tracking was simultaneously performed on the right side. The IVD region was divided into four similar sized quarters and included upper and lower endplates. Analysis of variance of upper adjacent level range of motion (ROM) and disc strain, normalized to intact, was performed between the groups. Statistical significant was set at P≤0.05. <h3>RESULTS</h3> Normalized ROM was significantly greater with FV than FP at upper adjacent level (L3-4) during right axial rotation (1.22 vs 0.99, 23% difference, p=0.047). Normalized IVD Pmax strains at the upper adjacent level (L3-4) were significantly greater with FV than FP in the anterior quadrant during right axial rotation (1.80 vs 0.83 (ratio to intact), 97% difference, p=0.003). However, there were no significant differences in ROM and disc Pmax or Pmin strains during flexion, extension and lateral bending. <h3>CONCLUSIONS</h3> Facet violations at the uppermost level of fusion construct during pedicle screw-rod fixation were associated with adjacent level torsional instability and the increase of IVD strain. This study suggested that the preservation of uppermost facet joint of fusion segment was helpful for alleviating adjacent segment mobility and stress concentrations of the IVD above the fusion segment. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

How I do it? Full endoscopic transforaminal approach for lumbar disc herniation that migrated bilaterally to four corners.

Despite of the evolution of endoscopic surgery, the literature on technique uniportal transforaminal endoscopic lumbar discectomy (TELD) for bilateral lesions is scarce. Unilateral TELD was performed in a patient with bilateral superior and inferior migrated, broad-based disc herniation presenting with an impaired neurological state. The key surgical steps focus on free mobility in Kambin triangle with the mobile outside-in technique and accessibility to contralateral lesions with an extensive annular resection procedure. TELD can be a surgical option for treating bilateral multiple direction migrated lumbar disc herniation with benefits of minimal neural retraction and facet joint preservation.

Unilateral biportal endoscopic decompression for degenerative lumbar canal stenosis.

Unilateral biportal endoscopic (UBE) decompression is a minimally invasive (MI) approach to treat degenerative lumbar canal stenosis (DLCS). Decompression can be performed in a clear and magnified surgical field with proper control of normal saline inflow and outflow. Clinical and radiographic data of 81 consecutive patients of DLCS treated between July 2018 and Feb 2019 using UBE techniques were reviewed. They were 38 males and 43 females with an average age of 70.2. Sixty-nine had pure canal stenosis and 12 patients had associated spondylolisthesis. Bilateral decompression via unilateral laminotomy was performed from the side on patients with more severe neurological symptoms. This is a retrospective study from chart review and image analysis. Therefore, we don't have formal ethical information for this study, and it is not mandatory in our hospital. At the final follow-up, the mean VAS for low back pain was improved from 4.3±3.0 to 1.2±1.0 and the VAS for leg symptoms was improved from 7.3±2.2 to 0.9±0.7. The mean JOA score and ODI was significantly improved from 13.3±7.9 to 25.3±5.0 and from 54.6±16.9 to 14.6±12.6, respectively. Modified Macnab criteria were excellent in 47 patients (58.0%), good in 29 (35.8%), fair in 5 (6.2%). The average hospital stay was 3.6±2.4 days. MRI before and after the operation showed the cross-sectional dural area (CSDA) was significantly increased from 71.4±36.5 to 177.3±59.2 mm2, corresponding to a 201.9%±188.0% increase. The percentage of facet joint preservation was 84.2% on the approach side and 92.9% on the contralateral side. Complications included 4 dural tears, 1 transient motor weakness, 1 inadequate decompression, and 1 epidural hematoma. With UBE techniques, decompression for DLCS can be performed safely and effectively. The soft tissue and facet joint destruction are minimized; therefore, it is possible to avoid spinal fusion as well as to preserve the segmental stability.

Combination of degenerative lumbar spinal stenosis and spinal deformity. Literature review

The study objective is to analyze currently available publications on spinal deformity in patients with degenerative lumbar spinal stenosis.Materials and methods. We analyzed 90 manuscripts published between 1980 and 2017.Results. We describe the parameters used to assess spinal deformity and evaluate their role for predicting the course of degenerative spinal disease. We provide the results of latest studies assessing the impact of spinal deformity on the outcome of surgical treatment in patients with degenerative lumbar spinal stenosis. We identified the following risk factors for scoliosis progression: wedge-shaped intervertebral disc in the frontal projection, low middle sacral axis, lateral spondylolisthesis, small L vertebral body, vertebral rotation, Cobb angle &gt;20°, and sagittal imbalance.Conclusion. We recommend decompressive interventions with facet joint preservation in patients with spinal deformity and degenerative lumbar spinal stenosis with no risk factors for scoliosis progression and radicular symptoms only (without pronounced low back pain). In patients with no risk factors for scoliosis progression, radicular symptoms, and low back pain, it is advisable to combine decompression with short fixation. For individuals at risk of scoliosis progression, we recommend supplementing decompression with long fixation exceeding scoliosis curve.

Facet Preserving Technique by En Bloc Flavectomy in Microscopic Posterior Decompression Surgery for Lumbar Spinal Stenosis: Semicircumferential Decompression (SCD).

Posterior decompression surgery which enlarges the spinal canal in cases with lumbar spinal stenosis is the most fundamental technique in spine surgery, but controversy still remains for the exact technique. Because nerve roots run under the ventral side on the superior articular process (SAP), achieving both facet joint preservation and nerve root decompression is problematic. In conventional laminotomies or laminectomies, medial facetectomies are performed to decompress the nerve root, but it is ideal to preserve the facet joints completely for preserving joint stability. We handle this problem with an original decompression technique, called "semicircumferential decompression." The main features of this procedure are an en bloc flavectomy and total preservation of facet joints. The procedure is performed under the microscope with a midline approach. The flavum is detached from the ventral surface of the SAP using a currete without disturbing the SAP. The facet joints are preserved completely. The advantage of an en bloc flavectomy is that we can remove the flavum attachment to the ventral surface of SAP totally without a medial facetectomy. Since 1991, we have performed this technique in more than 5000 cases. In this paper, we will explain the tips, pitfalls, and advantages of this technique.

Clinical and Radiological Outcomes after Microscopic Bilateral Decompression via a Unilateral Approach for Degenerative Lumbar Disease: Minimum 5-Year Follow-Up.

Study DesignA retrospective study.PurposeTo assess postoperative bone regrowth at surgical sites after lumbar decompression with >5 years of follow-up. Postoperative preservation of facet joints and segmental spinal instability following surgery were also evaluated.Overview of LiteraturePrevious reports have documented bone regrowth after conventional laminectomy or laminotomy and several factors associated with new bone formation.MethodsForty-nine patients who underwent microscopic bilateral decompression via a unilateral approach at L4–5 were reviewed. Primary outcomes included correlations among postoperative bone regrowth, preservation of facet joints, radiographic parameters, and clinical outcomes. Secondary outcomes included comparative analyses of radiographic parameters and clinical outcomes among preoperative diagnoses (lumbar spinal stenosis, degenerative spondylolisthesis, and degenerative lumbar scoliosis).ResultsThe average value of bone regrowth at the latest follow-up was significantly higher on the dorsal side of the facet joint (3.4 mm) than on the ventral side (1.3 mm). Percent facet joint preservation was significantly smaller on the approach side (79.2%) than on the contralateral side (95.2%). Bone regrowth showed a significant inverse correlation with age, but no significant correlation was observed with facet joint preservation, gender, postoperative segmental spinal motion, or clinical outcomes. Subanalysis of these data revealed that bone regrowth at the latest follow-up was significantly greater in patients with degenerative lumbar scoliosis than in those with lumbar spinal stenosis. Postoperative segmental spinal motion at L4–L5 did not progress significantly in patients with degenerative spondylolisthesis or degenerative lumbar scoliosis compared with those with lumbar spinal stenosis.ConclusionsMicroscopic bilateral decompression via a unilateral approach prevents postoperative spinal instability because of satisfactory preservation of facet joints, which may be the primary reason for inadequate bone regrowth. Postoperative bone regrowth was not related to clinical outcomes and postoperative segmental spinal instability.

Comparison of Three Different Paraspinous Unilateral Approaches to the Spinal Canal for Lumbar Decompression-Minimally 2-Year Postoperative Evaluation

Background: The purpose of this study is to investigate the differences of the clinical results and imaging findings among three different bilateral decompression via unilateral approach with a minimum 2-year follow-up period. Methods: Thirty consecutive patients with lumbar spinal canal stenosis who had undergone bilateral decompression via 3 different unilateral paraspinous approaches with a minimum 2-year follow-up period were chosen retrospectively for groups A (conventional open surgery), B (mini open surgery), and C (micro-endoscopic surgery). The clinical results and imaging findings of these three groups were then investigated. Results: A significant difference in length of incision and intraoperative blood loss per level decompressed was seen with group A>B>C. Operative time per level decompressed was longer in group C than in groups A or B. Japanese Orthopaedic Association (JOA) score recovery rate was lower in group B than in group C. The change ratios of cross-sectional area (CSA) of the ipsilateral and contralateral multifidus were smaller in group A than in groups B or C. Ipsilateral facet joint preservation was less in group A than group C, and contralateral facet joint preservation was less in group A than in groups B or C. The difference in change in slippage was greater in group A than in group C. Conclusion: This study revealed that bilateral decompression via a unilateral approach using mini open or microendoscopic procedures could be better surgical interventions compared to a conventional unilateral open approach for paravertebral muscle and facet joint preservation for at least 2 years.

Postoperative Clinical Outcome and Risk Factors for Poor Outcome of Foraminal and Extraforaminal Lumbar Disc Herniation.

ObjectiveWe evaluated postoperative outcomes in patients who have lumbar foraminal or extraforaminal disc herniation (FELDH) and suggested the risk factors for poor outcomes.MethodsA total of 234 patients were selected for this study. Pre- and post-operative Visual Analogue Scale (VAS) and Korean version Oswestry Disability Index (KODI) were evaluated and the changes of both score were calculated. Outcome was defined as excellent, good, fair, and poor based on Mcnab classification. The percentage of superior facetectomy was calculated by using the Maro-view 5.4 Picture Archiving Communication System (PACS).ResultsParamedian lumbar discectomy was performed in 180 patients and combined lumbar discectomy was performed in 54 patients. Paramedian lumbar discectomy group showed better outcome compared with combined discectomy group. p value of VAS change was 0.009 and KODI was 0.013. The average percentage of superior facetectomy was 33% (range, 0–79%) and it showed negative correlation with VAS and KODI changes (Pearson coefficient : -0.446 and -0.498, respectively). Excellent or good outcome cases (Group I) were 136 (58.1%) and fair or poor outcome cases (Group II) were 98 (41.9%). The percentage of superior facetectomy was 26.5% at Group I and 42.5% at Group II. There was significant difference in superior facetectomy percentage between Group I and II (p=0.000).ConclusionThis study demonstrated that paramedian lumbar discectomy with preservation of facet joints is an effective and good procedure for FELDH. At least 60% of facet should be preserved for excellent or good outcomes.

Two-Year Clinical and Radiological Outcomes of Open-Door Cervical Laminoplasty With Prophylactic Bilateral C4–C5 Foraminotomy in a Prospective Study

A prospective study. To evaluate the 2-year outcomes of open-door cervical laminoplasty with prophylactic bilateral C4-C5 foraminotomy. A prospective trial of prophylactic bilateral C4-C5 foraminotomy with open-door laminoplasty for cervical compression myelopathy showed a significant efficacy for preventing postoperative C5 palsy. However, in bilateral foraminotomy, there are concerns such as postoperative instability, hinge fracture, or nonunion, which may cause deterioration of neurological symptoms and neck pain. A prospective trial was performed in 141 patients between 2009 and 2010 (group F). A group of 141 patients who underwent open-door laminoplasty without prophylactic foraminotomy from 2006 to 2008 served as a control group (group NF). Here, we report 2-year radiological and clinical data for 121 patients (follow-up rate: 85.8%) in group F and 115 patients (81.6%) in group NF. The 2 groups were demographically similar, except for the operation time. In group F, the mean rate of facet joint preservation was 71.4%. C2-C7 and C4-C5 lordosis and C4 translational movement were maintained postoperatively in both groups. The range of motion of C2-C7 and C4-C5 significantly decreased to about 80% of the preoperative values in both groups (P < 0.01). These radiological parameters and the incidence of hinge fracture and nonunion did not differ significantly between the groups. Visual analogue scale scores for neck pain were unchanged and significant recoveries (P < 0.001) in Japanese Orthopaedic Association scores were found in both groups. There were no significant differences in these clinical scores between the groups. The incidences of C5 palsy were 1.7% and 7.0% in groups F and NF, respectively (P = 0.043). Prophylactic bilateral C4-C5 foraminotomy did not adversely affect the 2-year radiological and clinical outcomes. Therefore, we conclude that this approach is an effective and desirable procedure for preventing postoperative C5 palsy. 3.

Radiographic evaluation of postoperative bone regrowth after microscopic bilateral decompression via a unilateral approach for degenerative lumbar spondylolisthesis

Minimally invasive decompressive surgery using a microscope or endoscope has been widely performed for the treatment of lumbar spinal canal stenosis (LSS). In this study the authors aimed to assess outcomes following microscopic bilateral decompression via a unilateral approach (MBDU) in terms of postoperative bone regrowth and preservation of the facet joints in patients with degenerative lumbar spondylolisthesis (DS) as compared with those in patients with LSS. In the period from May 1998 to February 2007 at the authors' institution, 85 patients underwent MBDU at L4-5. Clinical outcome was evaluated before surgery and at the final follow-up using the Japanese Orthopaedic Association (JOA) score for low-back pain. The following radiographic parameters were assessed at the L4-5 segment before surgery and at the final follow-up: 1) percentage slip on standing lateral radiographs, 2) percentage slip on dynamic radiographs, 3) disc arc on dynamic radiographs, and 4) percentage of facet joint preservation on CT. Bone regrowth on the ventral and dorsal sides of the facet joint on CT were assessed at the final follow-up. The cases of 47 patients (23 with DS at L-4 and 24 with LSS at L4-5 without instability) who had a follow-up of at least 2 years were retrospectively reviewed. The improvement ratio in the JOA score, that is, the percentage improvement as indicated by the difference between preoperative and postoperative JOA scores, was not significantly different between patients with DS and LSS. The percentage slip had progressed at the latest follow-up in both groups (1.4% and 1.1%, respectively), and there was no significant difference between the 2 groups. The percentage of facet joint preservation in the DS and LSS groups was 72.8% and 83.4%, respectively, on the approach side and 95.5% and 96.5% on the contralateral side. Facet joint preservation was significantly less on the approach side than on the contralateral side in both groups. The average amount of bone regrowth on the dorsal and ventral sides of the facet joint was 3.4 and 0.9 mm, respectively, in the DS group and 2.0 and 1.0 mm in the LSS group. The difference between the 2 groups was not significant. Facet joint preservation and bone regrowth were not correlated with clinical outcomes. Microscopic bilateral decompression via a unilateral approach can prevent postoperative spinal instability because of good preservation of the posterior elements including the facet joints, which is thought to be the main reason for the relatively small amount of bone regrowth after surgery.