Clinical outcomes after microendoscopic laminotomy for lumbar spinal stenosis: a 5-year follow-up study

Comparative Analysis of Microendoscopic and Open Laminectomy for Single-Level Lumbar Spinal Stenosis at L1-L2 or L2-L3

BACKGROUND

Several reports have highlighted comparable surgical outcomes between microendoscopic laminectomy (MEL) and open laminectomy (open) for lumbar spinal stenosis. However, the unilateral approach in MEL may present challenges for the upper lumbar levels, where facet joints are located deeper inside. Our objective was to compare surgical outcomes and radiographic evaluations for single-level decompression cases at L1-L2 or L2-L3 between MEL and open laminectomy.

METHODS

We analyzed patients who underwent single-level decompression for upper lumbar spinal stenosis at 12 distinguished spine centers from April 2017 to September 2021. Baseline demographics, preoperative, and 1-year postoperative patient-reported outcomes, along with imaging parameters, were compared between the MEL and open groups. To account for potential confounding, patients' backgrounds were adjusted using the inverse probability weighting method based on propensity scores.

RESULTS

Among the 2487 patients undergoing decompression surgery, 118 patients (4.7%) underwent single-level decompression at L1-L2 or L2-L3. Finally, 80 patients (51 in the MEL group, 29 in the open group) with postoperative data were deemed eligible for analysis. The MEL group exhibited significantly improved postoperative EuroQol 5-Dimension values compared to the open group. Additionally, the MEL group showed a lower facet preservation rate according to computed tomography examination, whereas the open group had a higher incidence of retrolisthesis.

CONCLUSIONS

Although overall surgical outcomes were similar, the MEL group demonstrated potential advantages in enhancing EuroQol 5-Dimension scores. The MEL group's lower facet preservation rate did not translate into a higher postoperative instability rate.

Increased Surgical Experience in Microendoscopic Spinal Surgery Can Reduce Development of Postoperative Spinal Epidural Hematoma and Improve the Clinical Outcomes

No reports have previously evaluated the association between surgical technique and the incidence of postoperative spinal epidural hematoma (PSEH) following microendoscopic decompression surgery (MED). This study aimed to evaluate the association between the development of radiographic PSEH (rPSEH) following MED and microendoscopic surgical experience and postoperative clinical outcomes related to the quality of life (QoL). This retrospective cohort study included 3922 patients who had undergone MED performed by a single surgeon. rPSEH was defined as a hematoma that was identified via routine magnetic resonance images performed 3−4 days postoperatively. Patients were divided into rPSEH and control groups to identify the risk factor of rPSEH and assess clinical outcomes. In the multivariate analysis, age (p = 0.002), surgical experience (p = 0.003), surgical time (p = 0.038), multilevel decompression (p < 0.001), and diagnosis (p = 0.004) were identified as independent variables associated with rPSEH. Moreover, in mixed-effect models, the rPSEH group showed less improvement in Oswestry Disability Index (p = 0.014) than the control group. In conclusion, the surgical experience was identified as a risk factor for rPSEH that could lead to poor QoL. The sharing of microendoscopic surgical techniques among surgeons may reduce rPSEH incidence and improve patients’ QoL.

Thermal Dynamics of a Novel Radio-Frequency Device for Endoscopic Spine Surgery: An Experimental Model

STUDY DESIGN

Experimental study.

OBJECTIVE

In this study, the ambient temperature of a radiofrequency (RF) electrode tip was compared and analyzed in terms of products, mode, flow quantity, and flow rate.

SUMMARY OF BACKGROUND DATA

Endoscopic spine surgery is a widely used operation for degenerative lumbar stenosis and herniated lumbar disc. To perform endoscopic spine surgery, dedicated instruments like a RF generator and electrode are essential.

METHODS

An evaluation system capable of measuring temperature under equal conditions at a certain distance from the electrode tip was manufactured. The distance between the electrode tip and the temperature sensor was set to 1, 5, and 10 mm. The flow quantities of 0, 50, 100, and 150 mL/min and the flow rates of 0, 0.20, 0.53, and 0.80 m/s were compared and statistically analyzed.

RESULTS

The temperatures measured in the experiments conducted on the four combinations of RF device showed similar values, and showed differences according to the characteristics of each mode of the RF. As the distance between the electrode tip and the temperature sensor increased, the temperature decreased, and as flow quantity or flow rate increased, the temperature decreased. The maximum temperatures differed significantly according to flow quantity, between flow quantities of 0 and 100 mL/min (P  = 0.03) and between 0 and 150 mL/min (P ≤ 0.01). The maximum temperatures also differed significantly between the flow rate of 0 m/s, and the flow rates of 0.20, 0.53, and 0.80 m/s, with P ≤ 0.01 in all three comparisons.

CONCLUSION

This is the first study in which we made a customized RF temperature evaluation system and verified the temperature changes in various environments. When irrigation was performed, we could confirm that the maximum temperature was less than 60°C. Irrigation is considered essential in endoscopic spine surgery.

LEVEL OF EVIDENCE

3.

Microendoscopic Lumbar Posterior Decompression Surgery for Lumbar Spinal Stenosis: Literature Review

Lumbar spinal stenosis (LSS) is a common disease in the elderly, mostly due to degenerative changes in the lumbar spinal complex. Decompression surgery is the standard surgical treatment for LSS. Classically, total laminectomy—which involves resection of the spinous process, entire laminae and medial facet—has been the standard decompression technique; however, it can cause post-surgical instability. To overcome this disadvantage, various minimally invasive techniques that preserve the stabilization structures of the spine have been developed, and surgeons have begun to re-evaluate decompression surgery from the standpoint of reduced invasiveness and cost. More than two decades have passed since the introduction of microendoscopic spine surgery, and studies continue to shed light on its advantages and limitations as new knowledge becomes available. This article is a narrative review of the available literature, along with authors’ experience, regarding the indications, surgical techniques, clinical outcomes, and limitations/complications of microendoscopic decompression for LSS.

Anterior decompression through a posterior approach for thoracic myelopathy caused by ossification of the posterior longitudinal ligament: a novel concept in anterior decompression and technical notes with the preliminary outcomes

OBJECTIVE

Various surgical procedures are used to manage thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL). However, the outcomes of surgery for thoracic OPLL are generally unfavorable in comparison to surgery for cervical OPLL. Previous studies have shown a significant risk of perioperative complications in surgery for thoracic OPLL. Thus, a safe and secure surgical method to ensure better neurological recovery with less perioperative complications is needed. The authors report a novel concept of anterior decompression through a posterior approach aimed at anterior shift of the OPLL during surgery rather than extirpation or size reduction of the OPLL. This surgical technique can securely achieve anterior shift of the OPLL using a curved drill, threadwire saw, and curved rongeur. The preliminary outcomes were investigated to evaluate the safety and efficacy of this technique.

METHODS

This study included 10 consecutive patients who underwent surgery for thoracic OPLL. Surgical outcomes, including the ambulatory status, Japanese Orthopaedic Association (JOA) score, and perioperative complications, were investigated retrospectively. In this surgery, pedicle screws are introduced at least three levels above and below the corresponding levels. The laminae, facet joints, transverse processes, and pedicles are then removed bilaterally at levels wherein subsequent anterior decompression is performed. For anterior decompression, the OPLL and posterior portion of the vertebral bodies are partially resected using a high-speed drill with a curved burr, enabling the removal of osseous tissues just ventral to the spinal cord without retracting the dural sac. To securely shift the OPLL anteriorly, the intact PLL and posterior portion of the vertebral bodies cranial and caudal to the lesion are completely resected using a threadwire saw and/or curved rongeur. Rods are connected to the screws, and bone grafting is performed for posterolateral fusion.

RESULTS

Five patients were nonambulatory before surgery, but all were able to walk at the final follow-up. The average JOA score before surgery and at the final follow-up was 3.2 and 8.8 points, respectively. Notably, the mean recovery rate of JOA score was 72%. Furthermore, no patients showed neurological deterioration postoperatively.

CONCLUSIONS

The surgical technique is a useful alternative for safely achieving sufficient anterior decompression through a posterior approach and may consequently reduce the risk of postoperative neurological deterioration and improve surgical outcomes in patients with thoracic OPLL.

Risk Factors and Surgical Management of Recurrent Herniation after Full-Endoscopic Lumbar Discectomy Using Interlaminar Approach

Full-endoscopic lumbar discectomy (FED) is one of the least invasive procedures for lumbar disc herniation. Patients who receive FED for lumbar disc herniation may develop recurrent herniation at a frequency similar to conventional procedures. Reoperation and risk factors of recurrent lumbar disc herniation were investigated among 909 patients who received FED using an interlaminar approach (FED-IL). Sixty-five of the 909 patients received reoperation for recurrent herniation. Disc height, smoking, diabetes mellitus (DM), subligamentous extrusion (SE) type, and Modic change were identified as the risk factors for recurrence. Other indicators such as LL, Cobb angle, disc migration, age, sex, and body mass index (BMI) did not reach significance. Among 65 patients, reoperation was performed within 14 days following FED-IL (very early) in 7 patients, from 15 days to 3 months (early) in 14 patients, from 3 months to 1 year (midterm) in 17 patients, and after more than 1 year (late) in 27 patients. The very early group included a greater number of males, and the mean age was significantly lower in comparison to other groups. All patients in the very early group received FED-IL for reoperation. Reoperation within 2 weeks allows FED-IL to be performed without adhesion. Fusion surgery was performed on three cases in the early and midterm groups and on 10 cases in the late group, which increased over time as degenerative change and adhesion progressed. The procedure selected to treat recurrent herniation mostly depends on the surgeon’s preference. Revision FED-IL is the first choice for recurrent herniation in terms of minimizing surgical burden, whereas fusion surgery offers the advantage that discectomy can be performed through unscarred tissues. FED-IL is recommended for recurrent herniation within 2 weeks before adhesion progresses.

Long-term reoperation rates and causes for reoperations following lumbar microendoscopic discectomy and decompression: 10-year follow-up

OBJECTIVE

To investigate the 10-year rates and causes of reoperations following lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS), as well as to define the reoperations at index and different lumbar levels.

METHODS

Between June 2005 and May 2011, the same surgeon had been using MEDH and/or MEDS on 355 consecutive patients. The follow-up rate was 88.3%. The causes and rates of reoperations (RORs) were determined at 10 years after the initial operations.

RESULTS

The 10-year reoperation rate for all patients combined was 22.1% (67/303). The 10-year reoperation rate for all cases that underwent repeat operations in the same segment was 16.5% (50/303); the most frequent reason for reoperation (FRR) was recurrence of disc herniation (ROR, 25/251 = 9.96%), the second FRR was an increase of postoperative spondylolisthesis and/or instability (ROR, 8/303 = 2.64%), and the third FRR was surgical site infection (ROR, 5/303 = 1.65%). Ten-year reoperation rate for all cases that underwent repeat operation at different lumbar levels was 5.61% (17/303); the most FRR was new disc herniation at another lumbar level (ROR, 10/303 = 3.30%), the second FRR was residual segmental stenosis (ROR, 4/303 = 1.32%), and the third FRR was new segmental stenosis at other lumbar levels (ROR, 2/303 = 0.66%).

CONCLUSIONS

Three-fourths of all repeat operations were conducted in the same segment and one-fourth were performed at different lumbar levels. We believe that it is important to understand and prevent related problems.

Comparison between microendoscopic laminectomy and open posterior decompression surgery for single-level lumbar spinal stenosis: a multicenter retrospective cohort study

Background

Microendoscopic laminectomy (MEL), in which a 16-mm tubular retractor with an internal scope is used, has shown excellent surgical results for patients with lumbar spinal canal stenosis. However, no reports have directly compared MEL with open laminectomy. This study aimed to elucidate patient-reported outcomes (PROs) and perioperative complications in patients undergoing MEL versus open laminectomy.

Methods

This is a multicenter retrospective cohort study of prospectively registered patients who underwent lumbar spinal surgery at one of the six high-volume spine centers between April 2017 and September 2018. A total of 258 patients who underwent single posterior lumbar decompression at L4/L5 were enrolled in the study. With regard to demographic data, we prospectively used chart sheets to evaluate the diagnosis, operative procedure, operation time, estimated blood loss, and complications. The follow-up period was 1-year. PROs included a numerical rating scale (NRS) for lower back pain and leg pain, the Oswestry Disability Index (ODI), EuroQol 5 Dimension (EQ-5D), and patient satisfaction with the treatment.

Results

Of the 258 patients enrolled, 252 (97%) completed the 1-year follow-up. Of the 252, 130 underwent MEL (MEL group) and 122 underwent open decompression (open group). The MEL group required a significantly shorter operating time and sustained lesser intraoperative blood loss compared with the open group. The MEL group showed shorter length of postoperative hospitalization than the open group. The overall complication rate was similar (8.2% in the MEL group versus 7.7% in the open group), and the revision rate did not significantly differ. As for PROs, both preoperative and postoperative values did not significantly differ between the two groups. However, the satisfaction rate was higher in the MEL group (74%) than in the open group (53%) (p = 0.02).

Conclusions

MEL required a significantly shorter operating time and resulted in lesser intraoperative blood loss compared with laminectomy. Postoperative PROs and complication rates were not significantly different between the procedures, although MEL demonstrated a better satisfaction rate.

Microendoscopic Decompression for Lumbar Spinal Stenosis Associated with Adjacent Segment Disease following Lumbar Fusion Surgery: 5-year Follow-up of a Retrospective Case Series

BACKGROUND AND STUDY AIMS

 Surgical treatment options for lumbar spinal stenosis (LSS) based on adjacent segment disease (ASD) after spinal fusion typically involve decompression, with or without fusion, of the adjacent segment. The clinical benefits of microendoscopic decompression for LSS based on ASD have not yet been fully elucidated. We aimed to investigate the clinical results of microendoscopic spinal decompression surgery for LSS based on ASD.

PATIENTS AND METHODS

 From 2011 to 2014, consecutive patients who underwent microendoscopic spinal decompression without fusion for LSS based on ASD were enrolled. Data of 32 patients (17 men and 15 women, with a mean age of 70.5 years) were reviewed. Japanese Orthopaedic Association score and low back pain/leg pain visual analog scale score were utilized to measure neurologic and axial pain outcomes, respectively. Additionally, after the surgeries, we analyzed the magnetic resonance imaging (MRI), computed tomography (CT) scans, or radiographs to identify any new instabilities of the decompressed segments or progression of ASD adjacent to the decompressed segments.

RESULTS

 The Japanese Orthopaedic Association recovery rate at the 5-year postoperative visit was 49.2%. The visual analog scale scores for low back pain and leg pain were significantly improved. The minimum clinically important difference for leg pain (decrease by ≥24 mm) and clinically important difference for low back pain (decrease by ≥38 mm) were achieved in 84% (27/32) and 72% (23/32) of cases, respectively. Regarding new instability after microendoscopic decompression, no cases had apparent spinal instability at the decompression segment and adjacent segment to the decompressed segment.

CONCLUSIONS

 Microendoscopic spinal decompression is an effective treatment alternative for patients with LSS caused by ASD. The ability to perform neural decompression while maintaining key stabilizing structures minimizes subsequent clinical instability. The substantial clinical and economic benefits of this approach may make it a favorable alternative to performing concurrent fusion in many patients.

Improving effect of microendoscopic decompression surgery on low back pain in patients with lumbar spinal stenosis and predictive factors of postoperative residual low back pain: a single-center retrospective study

BACKGROUND

Although there are reports on the effectiveness of microendoscopic laminotomy using a spinal endoscope as decompression surgery for lumbar spinal stenosis, predicting the improvement of low back pain (LBP) still poses a challenge, and no clear index has been established. This study aimed to investigate whether microendoscopic laminotomy for lumbar spinal stenosis improves low back pain and determine the preoperative predictors of residual LBP.

METHODS

In this single-center retrospective study, we examined 202 consecutive patients who underwent microendoscopic laminotomy for lumbar spinal stenosis with a preoperative visual analog scale (VAS) score for LBP of ≥40 mm. The lumbar spine Japanese Orthopaedic Association (JOA), and VAS scores for LBP, leg pain (LP), and leg numbness (LN) were examined before and at 1 year after surgery. Patients with a 1-year postoperative LBP-VAS of ≥25 mm composed the residual LBP group. The preoperative predictive factors associated with postoperative residual LBP were analyzed.

RESULTS

JOA scores improved from 14.1 preoperatively to 20.2 postoperatively (p < 0.001), LBP-VAS improved from 66.7 to 29.7 mm (p < 0.001), LP-VAS improved from 63.8 to 31.2 mm (p < 0.001), and LN-VAS improved from 63.3 to 34.2 mm (p < 0.001). Ninety-eight patients (48.5%) had a postoperative LBP-VAS of ≥25 mm. Multiple logistic regression analysis revealed that Modic type 1 change (odds ratio [OR], 5.61; 95% confidence interval [CI], 1.68-18.68; p = 0.005), preoperative VAS for LBP ≥ 70 mm (OR, 2.19; 95% CI, 1.17-4.08; p = 0.014), and female sex (OR, 1.98; 95% CI, 1.09-3.89; p = 0.047) were preoperative predictors of residual LBP.

CONCLUSION

Microendoscopic decompression surgery had an ameliorating effect on LBP in lumbar spinal stenosis. Modic type 1 change, preoperative VAS for LBP, and female sex were predictors of postoperative residual LBP, which may be a useful index for surgical procedure selection.

Clinical Outcomes of Minimally Invasive Posterior Decompression for Lumbar Spinal Stenosis with Degenerative Spondylolisthesis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To compare the clinical outcomes 5 years after minimally invasive posterior decompression for lumber spinal stenosis (LSS) between patients with and without degenerative spondylolisthesis (DS).

SUMMARY OF BACKGROUND DATA

Indications for surgical procedures for patients with LSS and DS are still under investigation. Since minimally invasive surgery does not affect most anatomical structures, preoperative DS may not negatively affect the clinical outcomes of minimally invasive posterior decompression.

METHODS

Overall, 198 patients with LSS who underwent microendoscopic or microscopic decompression and were followed up for more than 5 years postoperatively were included in the present study. Patients who showed a segmental kyphosis >5° at the surgical level during flexion were treated with fusion surgery. However, other patients, including those with DS, were treated with posterior decompression. The patients were divided into two groups: the DS group included 82 patients with >3-mm slip and the non-DS group included 112 patients with ≤3-mm slip or without slip. A mixed-effects model adjusted for age and sex was used to compare the improvements in the visual analog scale score for low-back pain and the Japanese Orthopaedic Association score of the two groups. For subgroup analysis (n = 53), the changes in the preoperative physical component summary and the mental component summary of Short Form-36 of the two groups at 5 years after surgery were evaluated.

RESULTS

There was no significant difference in the improvement of preoperative low-back pain visual analog scale score and Japanese Orthopaedic Association score 5 years after surgery between the two groups. Subgroup analysis showed no significant difference between the two groups in the improvement of preoperative physical component summary and mental component summary 5 years after surgery.

CONCLUSION

After carefully eliminating patients with segmental instability, DS did not affect the clinical outcomes of minimally invasive decompression surgery.Level of Evidence: 3.

Management of degenerative spondylolisthesis: development of appropriate use criteria

BACKGROUND CONTEXT

Outcomes of treatment in care of patients with spinal disorders are directly related to patient selection and treatment indications. However, for many disorders, there is absence of consensus for precise indications. With the increasing emphasis on quality and value in spine care, it is essential that treatment recommendations and decisions are optimized.

PURPOSE

The purpose of the North American Spine Society Appropriate Use Criteria was to determine the appropriate (ie reasonable) multidisciplinary treatment recommendations for patients with degenerative spondylolisthesis across a spectrum of more common clinical scenarios.

STUDY DESIGN

A Modified Delphi process was used.

METHODS

The methodology was based on the Appropriate Use Criteria development process established by the Research AND Development Corporation. The topic of degenerative spondylolisthesis was selected by the committee, key modifiers determined, and consensus reached on standard definitions. A literature search and evidence analysis were completed by one work group simultaneously as scenarios were written, reviewed, and finalized by another work group. A separate multidisciplinary rating group was assembled. Based on the literature, provider experience, and group discussion, each scenario was scored on a nine-point scale on two separate occasions, once without discussion and then a second time following discussion based on the initial responses. The median rating for each scenario was then used to determine if indications were rarely appropriate (1 - 3), uncertain (4-6), or appropriate (7-9). Consensus was not mandatory.

RESULTS

There were 131 discrete scenarios. These addressed questions on bone grafting, imaging, mechanical instability, radiculopathy with or without neurological deficits, obesity, and yellow flags consisting of psychosocial and medical comorbidities. For most of these, appropriateness was established for physical therapy, injections, and various forms of surgical intervention. The diagnosis of spondylolisthesis should be determined by an upright x-ray. Scenarios pertaining to bone grafting suggested that patients should quit smoking prior to surgery, and that use of BMP should be reserved for patients who had risk factors for non-union. Across all clinical scenarios, physical therapy (PT) had an adjusted mean of 7.66, epidural steroid injections 5.76, and surgery 4.52. Physical therapy was appropriate in most scenarios, and most appropriate in patients with back pain and no neurological deficits. Epidural steroid injections were most appropriate in patients with radiculopathy. Surgery was generally more appropriate for patients with neurological deficits, higher disability scores, and dynamic spondylolisthesis. Mechanical back pain and presence of yellow flags tended to be less appropriate, and obesity in general had relatively little influence on decision making. Decompression alone was more strongly considered in the presence of static versus dynamic spondylolisthesis. On average, posterior fusion with or without interbody fusion was similarly appropriate, and generally more appropriate than stand-alone interbody fusion which was in turn more appropriate than interspinous spacers.

CONCLUSIONS

Multidisciplinary appropriate treatment criteria were generated based on the Research AND Development methodology. While there were consistent and significant differences between surgeons and non-surgeons, these differences were generally very small. This document provides comprehensive evidence-based recommendations for evaluation and treatment of degenerative spondylolisthesis. The document in its entirety will be found on the North American Spine Society website (https://www.spine.org/Research-Clinical-Care/Quality-Improvement/Appropriate-Use-Criteria).

Microendoscope-Assisted Decompression Surgery With Resection of Bony Fragment for Treating a Separation of Lumbar Posterior Ring Apophysis in Young Athletes

STUDY DESIGN

Case series.

OBJECTIVES

To report the clinical outcomes of the decompression procedure using the microendoscopic discectomy system for the treatment of a separation of lumbar posterior ring apophysis in young active athletes.

METHODS

We retrospectively reviewed 17 cases that underwent the microendoscopic surgery to treat a symptomatic separated lumbar ring apophysis between 2001 and 2014 at our institute or our associated hospital. The cases consisted of 15 males and 2 females, with their ages ranging from 12 to 19 years. The surgeries were performed at total of 18 lumbar levels, including 15 L4/5 and 3 L5/S1 levels. All patients were young athletes. We evaluated the following: (1) the Japanese Orthopaedic Association (JOA) score for low back pain, (2) recovery rates using Hirabayashi's method, (3) operating time, (4) intraoperative blood loss, (5) perioperative complications, (6) the status of comeback to sports, and (7) the period taken to return to sports.

RESULTS

The JOA score was improved after the surgery in all cases. Recovery rate was 92.0% ± 8.1%. The mean operating time per level was 89.2 ± 33.3 minutes. The mean intraoperative blood loss per level was 95.3 ± 93.1 mL. A pinhole size dural tear occurred in one case as a perioperative complication. All cases returned to sports. The mean period taken to return to sports was 10.9 ± 3.5 weeks.

CONCLUSION

Microendoscopic decompression surgery is useful for treating a separation of lumbar posterior ring apophysis.

Classification and prognostic factors of residual symptoms after minimally invasive lumbar decompression surgery using a cluster analysis: a 5-year follow-up cohort study

PURPOSE

Residual symptoms indicating incomplete remission of lower leg numbness or low back pain may occur after spine surgery. The purpose was to elucidate the pattern of residual symptoms 5 years after minimally invasive lumbar decompression surgery using a cluster analysis.

METHODS

The study comprised 193 patients with lumbar spinal stenosis (LSS) (108 men, 85 women) ranging in age from 40 to 86 years (mean, 67.9 years). Each patient underwent 5-year follow-up. The Japanese Orthopedic Association score and visual analog scale scores for low back pain, leg pain, and leg numbness at 5 years were entered into the cluster analysis to characterize postoperative residual symptoms. Other clinical data were analyzed to detect the factors significantly related to each cluster.

RESULTS

The analysis yielded four clusters representing different patterns of residual symptoms. Patients in cluster 1 (57.0%) were substantially improved and had few residual symptoms of LSS. Patients in cluster 2 (11.4%) were poorly improved and had major residual symptoms. Patients in cluster 3 (17.6%) were greatly improved but had mild residual low back pain. Patients in cluster 4 (14.0%) were improved but had severe residual leg numbness. Prognostic factors of cluster 2 were a short maximum walking distance, motor weakness, resting lower leg numbness, cofounding scoliosis, and high sagittal vertical axis.

CONCLUSIONS

This is the first study to identify specific patterns of residual symptoms of LSS after decompression surgery. Our results will contribute to acquisition of preoperative informed consent and identification of patients with the best chance of postoperative improvement.

Is Decompression and Partial Discectomy Advantageous Over Decompression Alone in Microendoscopic Decompression Of Monosegmental Unilateral Lumbar Recess Stenosis?

BACKGROUND

Endoscopic techniques are well accepted as surgical technique for decompression of lumbar lateral recess stenosis (LRS). It is uncertain if there is a difference in clinical outcome for decompression alone (DA) or decompression with partial discectomy (DPD) for the treatment of LRS.

METHODS

All files of patients who underwent an endoscopic procedure for lumbar LRS were identified from a prospectively collected database. Preoperative magnetic resonance imaging and endoscopic video were analyzed with special focus on the technique of nerve root decompression. Clinical outcome was assessed via a personal examination, a standardized questionnaire including the numeric rating scale (NRS) for leg and back pain, the Oswestry disability index (ODI), and the modified MacNab criteria to assess functional outcome and clinical success.

RESULTS

Sixty-six patients were identified of which 57 attended for evaluation (86.4%). DA was performed in 15 (26.3%) patients and DPD in 42 patients (73.7%). The mean follow-up was 45.0 months (range: 16-82 months). Fifty-two patients reported to be free of leg pain (91.1%), 42 patients had no noticeable back pain (73.7%), 49 patients had full muscle strength (85.9%), and 48 patients had no sensory disturbance (84.2%). The mean NRS for leg pain was 1, the mean NRS for back pain was 2, mean ODI was 16% (range: 0%-60%). Clinical success was noted in 49 patients (85.9%) and it was significantly higher for patients following DPD (P = .024). The overall repeat procedure rate was 12% with reoperation rate at the index segment in 10.5% of cases. There were no significant differences with respect to leg and back pain, ODI, and reoperation between both groups.

CONCLUSION

Microendoscopic DPD of LRS achieves a 92% clinical success rate which is significantly higher compared to 67% clinical success achieved by DA. There was no significant difference for the rate of reoperation, leg and back pain, and ODI.

LEVEL OF EVIDENCE

4.

The effect of preoperative degenerative spondylolisthesis on postoperative outcomes of degenerative lumbar spinal stenosis: A single-center cohort study protocol

BACKGROUND

Most degenerative lumbar spinal stenosis (DLSS) patients primitively received the conservative treatment to control symptoms. In order to develop an optimal surgical treatment strategy, it is very significant to understand how the degenerative lumbar spondylolisthesis (DS) affects the effect of decompression in the DLSS. Thus, the aim of this current study was to explore whether the concomitant DS would affect the effect of decompression alone in the patients with DLSS.

METHODS

The current study was carried out at our hospital and it was approved through our institutional review committee of General Hospital of Ningxia Medical University. During the period from January 2015 to December 2017, in our study, we identified consecutive patients who received the minimally invasive laminectomy to treat the DLSS. The inclusion criterion included radicular leg pain or neurogenic claudication with the neurological symptoms associated with DLSS syndrome, magnetic resonance imaging of the lumbar spine reveals at least 1 level of serious stenosis, the conservative treatment failed for at least 3 months, and patients agreed to provide the postoperative details. The major outcomes of this present research was Oswestry Disability Index. Secondary outcomes of this current study involved visual analog score, short form-36, surgical revision rate as well as complications.

RESULTS

We assumed that previous DS possessed a negative effect on the postoperative results of the DLSS patients.

TRIAL REGISTRATION

researchregistry5943.

Clinical outcomes of MED and iLESSYS® Delta for the treatment of lumbar central spinal stenosis and lateral recess stenosis: A comparison study

Microendoscopic discectomy (MED) is an established procedure used to treat lumbar central spinal stenosis (LCSS) and lateral recess stenosis (LRS). The Interlaminar Endoscopic Surgical System iLESSYS^® Delta approach has been developed from the traditional interlaminar endoscopic technique for the treatment of LCSS and LRS. In the present study, MED was used as a reference to evaluate this newly developed approach. A total of 82 and 52 patients with radicular leg pain and/or neurogenic claudication symptoms were treated by spinal canal decompression using the MED or iLESSYS^® Delta approach, respectively. The clinical outcomes of the patients were analyzed using the Modified MacNab's criteria, visual analogue scale (VAS) leg pain score, VAS back pain score and the Oswestry Disability Index (ODI) score. Finally, the effectiveness of the decompression was evaluated on a cross-sectional area of the dural sac (CSAD) at the disc level. The incision length in the iLESSYS^® Delta group was significantly decreased compared with the MED group (P<0.05); however, the duration of the operation in the iLESSYS^® Delta group was significantly longer compared with the MED group (P<0.05). The VAS score of the back and ODI score in the iLESSYS^® Delta group were significantly decreased compared with the MED group at the 1-week follow-up (P<0.0125). The postoperative CSAD was also significantly increased in both groups compared with before the operation (P<0.05); however, there were no significant differences in the postoperative CSAD between the two groups. The good-to-excellent rates of the MED and iLESSYS^® Delta approach were 89.0 and 90.4%, respectively, whereas the complication rates of the MED and iLESSYS^® Delta system were 3.66 and 3.85% in the two groups, respectively. In conclusion, the iLESSYS^® Delta approach was identified to be comparable with the MED approach for treating LCSS and LRS, demonstrating both precise and limited decompression. In addition, the iLESSYS^® Delta approach may reduce the short-term back pain and promote faster recovery compared with the MED.

Microendoscopic discectomy versus minimally invasive transforaminal lumbar interbody fusion for lumbar spinal stenosis without spondylolisthesis

Micoendoscopic discectomy (MED) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) has become alternatives of the traditional open decompression surgery alone and decompression plus fusion surgery in the treatment of lumbar spinal stenosis (LSS). To date, there is no study focusing on the comparison of clinical outcomes after MED and MIS-TLIF for LSS without spondylolisthesis.Four hundred ninety-seven patients who underwent MED (236 cases) or MIS-TLIF (261 cases) for LSS without spondylolisthesis were included in this study. Perioperative outcomes (hospital stay, operation time and blood loss), cost, functional scores (Oswestry Disability Index, 12-item short form health survey) with a 24-month follow-up visit, complication and reoperation condition within 24 months after surgery were recorded and assessed.No significant difference of clinical outcomes over time was observed between these 2 surgical approaches. Compared with MIS-TLIF, MED was associated with greater satisfaction at 1-month time point postoperatively, whereas this effect was equalized at 3-month time point postoperatively. MED brought advantages in shorter hospital stay, shorter operation time, less blood loss, and less cost over MIS-TLIF.There was no significant difference in 24-month function scores over time between MED group and MIS-TLIF group. Compared with MIS-TLIF, MED could result in a better perioperative effect and less cost.

Unilateral biportal endoscopic decompression for degenerative lumbar canal stenosis

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Five-year Reoperation Rates and Causes for Reoperations Following Lumbar Microendoscopic Discectomy and Decompression

STUDY DESIGN

Retrospective study of prospectively collected outcome data.

OBJECTIVE

The aim of this study was to investigate reoperation cases and determine whether or not the experience period of a single surgeon was associated with the causes of reoperations following lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS).

SUMMARY OF BACKGROUND DATA

There have been few studies that investigated reoperation cases following MEDH and MEDS.

METHODS

Between June 2005 (first experience of MEDH) and September 2013, the same surgeon had been using MEDH and/or MEDS on 441 consecutive patients. The follow-up rate was 89.3%. The causes and rates of reoperations (RORs) were determined at 5 years after the initial operations. We also investigated the experience period of a single surgeon (EPS, interval between June 2005 and initial operation: median, 37 months).

RESULTS

The 5-year reoperation rate for all patients combined was 12.4% (49/394). The main causes for reoperations were recurrence of disc herniation (ROR, 7.01%) and increase of postoperative spondylolisthesis and/or instability (ROR, 9/394 = 2.28%); two of the nine cases were caused by excessive decompression, and the EPSs were 11 and 16 months. The other causes for reoperations were postoperative epidural hematoma (ROR, 0.76%; median EPS, 20 months), insufficient decompression (ROR, 0.25%; EPS, 17 months), and residual segmental scoliosis (ROR, 7.69%); two segmental scoliosis cases did not provide relief from sciatica, and therefore L4/5 transforaminal interbody fusions were performed.

CONCLUSION

Postoperative epidural hematoma and excessive or insufficient decompression were often observed in the initial series of patients as the causes for reoperations. We think that it is important to be aware of and prevent such potential problems in any initial series of patients, as there are limitations to any surgical indications for the use of microendoscopic decompression for degenerative segmental scoliosis because of original traction and/or kinking of nerve roots.

LEVEL OF EVIDENCE

4.

Influence of incidental dural tears and their primary microendoscopic repairs on surgical outcomes in patients undergoing microendoscopic lumbar surgery

BACKGROUND CONTEXT

Dural tear represents a common complication of microendoscopic spine surgery that may lead to postoperative sequelae including insufficient decompression, cerebrospinal fluid fistula, intracranial hypotension, and subdural/intraparenchymal bleeding. The gold standard to manage intraoperative dural tears is primary repair. However, the downside of conversion to open surgery can be detrimental. Therefore, understanding the most appropriate strategy for microendoscopic dural repair and its impact on postoperative outcomes is of importance.

PURPOSE

The purpose of this study was to investigate the incidence of dural tears in patients undergoing microendoscopic lumbar surgery and to elucidate their influence on surgical outcomes whenever proper repair is accomplished microendoscopically without conversion to open surgery.

STUDY DESIGN/SETTING

A retrospective multicenter cohort study of prospectively enrolled patients using a propensity-matched analysis.

PATIENT SAMPLE

A total of 922 consecutive patients underwent microendoscopic surgery of the lumbar spine between February and December 2012 in the three institutions belonging to our study group.

OUTCOME MEASURES

Outcome measures included the Numeric Rating Scale for back and leg pain, Oswestry Disability Index, Japanese Orthopaedic Association score, Short Form-36, and a patients' satisfaction scale.

METHODS

All incidental dural tears were repaired by microendoscopic suture of the dura mater from inside to outside using double-arm needles and/or by fibrin glue coverage without being converted to open surgery. Surgical outcomes were compared between patients with and without dural tears using a propensity-matched analysis.

RESULTS

Microendoscopic discectomy for lumbar disc herniation was performed on 474 patients, whereas microendoscopic laminectomy and posterior lumbar interbody fusion for lumbar canal stenosis were performed on 271 and 177 patients, respectively. Dural tears occurred in 49 (5.3%) patients. Of these, 23 (2.5%) patients required suture repair, whereas the rest received a fibrin patch for a pinhole tear, all of which were successfully performed under microendoscopy. Six hundred (65.1%) patients responded pre- and postoperatively to the questionnaire. Of them, the responses of 38 patients with dural tears were compared with those of 38 matched patients. No significant differences in any outcome measures were observed between the two groups.

CONCLUSIONS

In conclusion, all dural tears in our cases were managed without conversion to open surgery and did not influence surgical outcomes.

Does Concomitant Degenerative Spondylolisthesis Influence the Outcome of Decompression Alone in Degenerative Lumbar Spinal Stenosis? A Meta-Analysis of Comparative Studies

OBJECTIVE

To investigate whether the preoperative presence of degenerative spondylolisthesis (DS) worsens the outcome of patients undergoing decompression alone for degenerative lumbar stenosis.

METHODS

We conducted a comprehensive search in the PubMed, Embase, and Cochrane Library databases. All comparative studies were included in this meta-analysis. The literature search, data extraction, and quality assessment were conducted by 2 independent reviewers. The functional outcomes were clinical scores and reoperation rate. The radiologic outcomes were slippage rate and postoperative instability rate.

RESULTS

A total of 11 studies with 1081 cases, including 469 cases of degenerative lumbar stenosis with DS (DS group) and 612 degenerative lumbar stenosis without spondylolisthesis (noDS group), were enrolled in our meta-analysis. There were no significant differences between the 2 groups for functional outcomes in terms of Japanese Orthopedic Association score, Japanese Orthopedic Association recovery rate, Oswestry Disability Index score, visual analog scale back/leg, and reoperation rate after decompression alone. For the radiologic outcomes, slippage rate was found not changed significantly before and after minimally invasive decompression alone in the DS group and the postoperative instability rate did not differ significantly between the 2 groups after decompression alone by a minimally invasive method.

CONCLUSIONS

Our meta-analysis revealed that concomitant DS (Meyerding grade I-II) does not influence the outcome of decompression alone in degenerative lumbar spinal stenosis, especially when a minimally invasive procedure was performed and patients did not have predominant symptoms of mechanical back pain. The presence of DS should not be an indication for fusion surgery in degenerative lumbar spinal stenosis.

Surgical Outcomes and Limitations of Decompression Surgery for Degenerative Spondylolisthesis

STUDY DESIGN

A retrospective study.

OBJECTIVES

To investigate surgical outcomes and limitations of decompression surgery for degenerative spondylolisthesis.

METHODS

One hundred patients with degenerative spondylolisthesis who underwent decompression surgery alone were included in this study. The average follow-up period was 3.7 years. Radiography and magnetic resonance imaging were used for radiological assessment. Patients with a recovery rate of >50% throughout the study period were classified as the control group (Group C), while those with a recovery rate of <50% throughout the study period were classified as the poor group (Group P). Patients that had improved symptoms, and yet later showed neurological deterioration due to foraminal stenosis at the same level were classified as the exiting nerve root radiculopathy group (Group E), while those who showed deterioration due to slip progression at the same level were classified as the traversing nerve root radiculopathy group (Group T).

RESULTS

Patient distribution in each group was 73, 12, 7, and 8 in Groups C, P, E, and T, respectively. As for preoperative radiological features, slippage and an upper migrated disc in Group P, disc wedging and an upper migrated disc in Group E, and lamina inclination and posterior opening in Group T were evident. The cutoff value of preoperative slippage with a poor outcome was 13%.

CONCLUSIONS

Surgical outcomes of decompression surgery for degenerative spondylolisthesis were successful in 73% cases. Preoperative radiological features for poor outcomes were slippage of more than 13%, an upper migrated disc, disc wedging, and lamina inclination.

Comparison of minimally invasive decompression and combined minimally invasive decompression and fusion in patients with degenerative spondylolisthesis with instability

Posterior lumbar interbody fusion with cortical bone trajectory (CBT-PLIF) is a form of minimally invasive decompression and fusion, whereas microendoscopic laminotomy (MEL) is a form of minimally invasive decompression surgery. No study has compared the clinical outcomes of the two methods for patients who have degenerative spondylolisthesis (DS) with instability. In this study, CBT-PLIF and MEL were both offered to 64 patients who met the inclusion criteria. Each patient then selected his or her preferred treatment. Twenty patients received CBT-PLIF. They were matched to 30 of the 44 patients receiving MEL based on age, sex, disease duration, and surgical levels. The 20 patients with CBT-PLIF formed the CBT group and the 30 matched patients with MEL formed the MEL group. At 2 years of follow-up, Japanese Orthopaedic Association scores improved to 72.6% and 70.5% in the CBT and MEL groups, respectively. The difference in scores was not statistically significant. Further, improvements in visual analogue scale scores for back and leg symptom did not differ significantly between the two groups. Regarding complications, 1 CBT-group patient (5%) had adjacent-segment degeneration and 7 MEL-group patients (23%) had same-segment degeneration. Three CBT-group patients (15%) and 5 MEL-group patients (16%) required reoperation within the follow-up period. In summary, among patients who had DS with instability, MEL and CBT-PLIF offered comparable clinical outcomes at 2 years of follow-up. Although the rate of segmental degeneration was relatively high in the MEL group, both groups had similar reoperation rates.

The Learning Process of Endoscopic Spinal Surgery for Degenerative Cervical and Lumbar Disorders Using the EasyGO! System

BACKGROUND

Among spinal surgeons, the safety of endoscopic spinal techniques has been criticized as the result of a prolonged learning curve and divergent surgical technique from traditional microsurgery. In this manuscript, the authors assessed the learning curve of 4 experienced microsurgical neurosurgeons in endoscopic spinal surgery.

METHODS

Retrospectively, the surgical reports, the endoscopic video recording, and the files of all patients who underwent an endoscopic procedure for the treatment of cervical and lumbar disc herniation from January 2011 to December 2017 were reviewed. The learning process was assessed via several parameters: surgical time, intraoperative complications, dural tear, nerve root injury, conversion to microsurgery, new postoperative neurologic deficits, repeated procedure, and early recurrent disc herniation.

RESULTS

The learning process of for 4 surgeons was assessed on the basis of 308 procedures. The mean surgical time for the initial procedure ranges from 58 to 97 minutes and improved to 51-85 minutes for the last procedures. A shorter surgical time had no influence on the rate of intraoperative complication and repeated procedure. Increased working space had a significant influence on the surgical time. The number of procedure to reach the asymptote varied from 10 to 20 depending on the endoscopic system and the surgeon.

CONCLUSIONS

The learning process in endoscopic tubular-assisted spinal surgery is variable, and the asymptote might be reached after 10-20 procedures. The amount of working space and instrument angulation affects the surgical time. The decrease of surgical time had no significant influence on the rate of intraoperative complication and repeated procedures.

Clinical Outcome of Muscle-Preserving Interlaminar Decompression (MILD) for Lumbar Spinal Canal Stenosis: Minimum 5-Year Follow-Up Study

Introduction

Favorable short-term outcomes have been reported following muscle-preserving interlaminar decompression (MILD), a less invasive decompression surgery for lumbar spinal canal stenosis (LSCS). However, there are no reports of mid- to long-term outcomes. The purpose of this study was to evaluate the clinical outcomes five or more years after treatment of LSCS with MILD.

Methods

Subjects were 84 cases with LSCS (44 males; mean age, 68.7 years) examined five or more years after MILD. All patients had leg pain symptoms, with claudication and/or radicular pain. The patients were divided into three groups depending on the spinal deformity: 44 cases were without deformity (N group); 20 had degenerative spondylolisthesis (DS group); and 20 had degenerative scoliosis (DLS group). The clinical evaluation was performed using Japanese Orthopedic Association (JOA) scores, and revision surgeries were examined. Changes in lumbar alignment and stability were evaluated using plain radiographs.

Results

The overall JOA score recovery rate was 65.5% at final follow-up. The recovery rate was 69.5% in the N group, 65.2% in the DS group, and 54.0% in the DLS group, with the rate of the DLS group being significantly lower. There were 16 revision surgery cases (19.0%): seven in the N group (15.9%), three in the DS group (15.0%) and six in the DLS group (30.0%). There were no significant differences between pre- and postoperative total lumbar alignment or dynamic intervertebral angle in any of the groups, slip percentage in the DS group, or Cobb angle in the DLS group.

Conclusions

The mid-term clinical results of MILD were satisfactory, including in cases with deformity, and there was no major impact on radiologic lumbar alignment or stability. The clinical outcomes of cases with degenerative scoliosis were significantly less favorable and the revision rate was high. This should be taken into consideration when deciding on the surgical procedure.

A new concept of transforaminal ventral facetectomy including simultaneous decompression of foraminal and lateral recess stenosis: Technical considerations in a fresh cadaver model and a literature review

Percutaneous endoscopic surgery for the lumbar spine, which was established in the last decade, requires only an 8-mm skin incision and causes minimal damage to the paravertebral muscles; thus, it is considered to be a minimally invasive technique for spinal surgery. It has been used to perform percutaneous endoscopic discectomy via two main approaches: the TF approach is a posterolateral one through the intervertebral foramen and can be done under local anesthesia; the IL approach is a more traditional one through the interlaminar space and is difficult to perform under local anesthesia. Recently, these techniques have been applied for lumbar spinal stenosis (LSS), the TF method for foraminal stenosis under local anesthesia, and the IL method for central and lateral recess stenosis under general anesthesia. In this study, using a fresh human cadaver model, we performed simultaneous decompression of the lateral recess and foraminal stenosis at L4-5 using the TF approach. Computed tomography confirmed enlargement of the lateral recess and intervertebral foramen. This technique, which can be performed under local anesthesia, should benefit elderly patients with LSS and poor general condition due to multiple comorbidities. Finally, we introduce the concept of percutaneous transforaminal ventral facetectomy using a spinal percutaneous endoscope. J. Med. Invest. 64: 1-6, February, 2017.

Mechanical stress induces elastic fibre disruption and cartilage matrix increase in ligamentum flavum

Lumbar spinal stenosis (LSS) is one of the most frequent causes of low back pain and gait disturbance in the elderly. Ligamentum flavum (LF) hypertrophy is the main pathomechanism of LSS, but the reason for its occurrence is not clearly elucidated. In this study, we established a novel animal model of intervertebral mechanical stress concentration and investigated the biological property of the LF. The LF with mechanical stress concentration showed degeneration with elastic fibres disruption and cartilage matrix increase, which are similar to the findings in hypertrophied LF from patients with LSS. By contrast, decreased Col2a1 expression was found in the LF at fixed levels, in which mechanical stress was strongly reduced. These findings indicate that mechanical stress plays a crucial role in LF hypertrophy through cartilage matrix increase. The findings also suggest that fusion surgery, which eliminates intervertebral instability, may change the property of the LF and lead to the relief of patients' symptoms.

Long-term Clinical and Radiological Outcomes after Central Decompressive Laminoplasty for Lumbar Spinal Stenosis

OBJECTIVE

There are many technical modifications of decompressive lumbar laminectomy. The purpose of this study was to report long-term clinical and radiological outcomes of central decompressive laminoplasty (CDL), the corresponding author's own modification of lumbar laminectomy for lumbar spinal stenosis (LSS).

METHODS

Among 100 patients who underwent CDL by a single surgeon between December 2010 and March 2014, 68 patients were included in this study. Mean follow-up time was 37.7 months. Clinical and radiological data were gathered prospectively and reviewed retrospectively. Clinical outcome was measured by using visual analog scale (VAS) for back/buttock and leg, and the Oswestry Disability Index (ODI). Radiological outcome was measured by neutral slippage percentage, dynamic slippage percentage, and dynamic intervertebral angel on sagittal X-ray. Outcomes after CDL were assessed by changes of clinical and radiological parameters from the baseline. Mixed effect model with random patients' effect as used to test for differences in the repeated measured clinical and radiological data.

RESULTS

The patients had no serious complications with an uneventful recovery during the early postoperative period. In the early postoperative period, VAS scores for back/buttock and leg improved significantly and were kept with time (p<0.001). ODI also improved significantly during the postoperative follow-up period (p<0.001). The radiologic parameters were well maintained and showed no progression of instability. During the follow-up, a case of herniated disc at same level recurrence was noted after lifting trauma, and 2 adjacent foraminal stenosis needed additional surgery.

CONCLUSION

CDL provides long-term pain relief and functional restoration without progression of radiological instability.

Minimally invasive decompression surgery for lumbar spinal stenosis with degenerative scoliosis: Predictive factors of radiographic and clinical outcomes

There is ongoing controversy regarding the most appropriate surgical treatment for lumbar spinal stenosis (LSS) with concurrent degenerative lumbar scoliosis (DLS): decompression alone, decompression with limited spinal fusion, or long spinal fusion for deformity correction. The coexistence of degenerative stenosis and deformity is a common scenario; Nonetheless, selecting the appropriate surgical intervention requires thorough understanding of the patients clinical symptomatology as well as radiographic parameters. Minimally invasive (MIS) decompression surgery was performed for LSS patients with DLS. The aims of this study were (1) to investigate the clinical outcomes of MIS decompression surgery in LSS patients with DLS, and (2) to identify the predictive factors for both radiographic and clinical outcomes after MIS surgery. 438 consecutive patients were enrolled in this study. Inclusion criteria was evidence of LSS and DLS with coronal curvature measuring greater than 10°. The Japanese Orthopaedic Association (JOA) score, JOA recovery rate, low back pain (LBP), and radiographic features were evaluated preoperatively and at over 2 years postoperatively. Of the 438 patients, 122 were included in final analysis, with a mean follow-up of 2.4 years. The JOA recovery rate was 47.6%. LBP was significantly improved at final follow-up. Cobb angle was maintained for 2 years postoperatively (p = 0.159). Clinical outcomes in foraminal stenosis patients were significantly related to sex, preoperative high Cobb angle and progression of scoliosis (p = 0.008). In the severe scoliosis patients, the JOA recovery was 44%, and was significantly depended on progression of scoliosis (Cobb angle: preoperation 29.6°, 2-years follow-up 36.9°) and mismatch between the pelvic incidence (PI) and the lumbar lordosis (LL) (preoperative PI-LL 35.5 ± 21.2°) (p = 0.028). This study investigated clinical outcomes of MIS decompression surgery in LSS patients with DLS. The predictive risk factors of clinical outcomes were severe scoliosis, foramina stenosis, progressive scoliosis and large mismatch of PI-LL.