Comparison of clinical outcomes following minimally invasive or lumbar endoscopic unilateral laminotomy for bilateral decompression

Lynn B. McGrath Jr. Department of Neurological Surgery, University of Washington, Seattle, Washington

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Gabrielle A. White-Dzuro Department of Neurological Surgery, University of Washington, Seattle, Washington

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Christoph P. Hofstetter Department of Neurological Surgery, University of Washington, Seattle, Washington

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OBJECTIVE

Minimally invasive lumbar unilateral tubular laminotomy for bilateral decompression has gradually gained acceptance as a less destabilizing but efficacious and safe alternative to traditional open decompression techniques. The authors have further advanced the principles of minimally invasive surgery (MIS) by utilizing working-channel endoscope–based techniques. Full-endoscopic technique allows for high-resolution off-axis visualization of neural structures within the lateral recess, thereby minimizing the need for facet joint resection. The relative efficacy and safety of MIS and full-endoscopic techniques have not been directly compared.

METHODS

A retrospective analysis of 95 consecutive patients undergoing either MIS (n = 45) or endoscopic (n = 50) unilateral laminotomies for bilateral decompression in cases of lumbar spinal stenosis was performed. Patient demographics, operative details, clinical outcomes, and complications were reviewed.

RESULTS

The patient cohort consisted of 41 female and 54 male patients whose average age was 62 years. Half of the patients had single-level, one-third had 2-level, and the remaining patients had 3- or 4-level procedures. The surgical time for endoscopic technique was significantly longer per level compared to MIS (161.8 ± 6.8 minutes vs 99.3 ± 4.6 minutes; p < 0.001). Hospital stay for MIS patients was on average 2.4 ± 0.5 days compared to 0.7 ± 0.1 days for endoscopic patients (p = 0.001). At the 1-year follow-up, endoscopic patients had a significantly lower visual analog scale score for leg pain than MIS patients (1.3 ± 0.3 vs 3.0 ± 0.5; p < 0.01). Moreover, the back pain disability index score was significantly lower in the endoscopic cohort than in the MIS cohort (20.7 ± 3.4 vs 35.9 ± 4.1; p < 0.01). Two patients in the MIS group (epidural hematoma) and one patient in the endoscopic group (disc herniation) required a return to the operating room acutely after surgery (< 14 days).

CONCLUSIONS

Lumbar endoscopic unilateral laminotomy for bilateral decompression is a safe and effective surgical procedure with favorable complication profile and patient outcomes.

ABBREVIATIONS

AP = anteroposterior; BMI = body mass index; MCID = minimally clinically important difference; MIS = minimally invasive surgery; ODI = Oswestry Disability Index; SAP = superior articular process; ULBD = unilateral laminotomy for bilateral decompression; VAS = visual analog scale.

OBJECTIVE

Minimally invasive lumbar unilateral tubular laminotomy for bilateral decompression has gradually gained acceptance as a less destabilizing but efficacious and safe alternative to traditional open decompression techniques. The authors have further advanced the principles of minimally invasive surgery (MIS) by utilizing working-channel endoscope–based techniques. Full-endoscopic technique allows for high-resolution off-axis visualization of neural structures within the lateral recess, thereby minimizing the need for facet joint resection. The relative efficacy and safety of MIS and full-endoscopic techniques have not been directly compared.

METHODS

A retrospective analysis of 95 consecutive patients undergoing either MIS (n = 45) or endoscopic (n = 50) unilateral laminotomies for bilateral decompression in cases of lumbar spinal stenosis was performed. Patient demographics, operative details, clinical outcomes, and complications were reviewed.

RESULTS

The patient cohort consisted of 41 female and 54 male patients whose average age was 62 years. Half of the patients had single-level, one-third had 2-level, and the remaining patients had 3- or 4-level procedures. The surgical time for endoscopic technique was significantly longer per level compared to MIS (161.8 ± 6.8 minutes vs 99.3 ± 4.6 minutes; p < 0.001). Hospital stay for MIS patients was on average 2.4 ± 0.5 days compared to 0.7 ± 0.1 days for endoscopic patients (p = 0.001). At the 1-year follow-up, endoscopic patients had a significantly lower visual analog scale score for leg pain than MIS patients (1.3 ± 0.3 vs 3.0 ± 0.5; p < 0.01). Moreover, the back pain disability index score was significantly lower in the endoscopic cohort than in the MIS cohort (20.7 ± 3.4 vs 35.9 ± 4.1; p < 0.01). Two patients in the MIS group (epidural hematoma) and one patient in the endoscopic group (disc herniation) required a return to the operating room acutely after surgery (< 14 days).

CONCLUSIONS

Lumbar endoscopic unilateral laminotomy for bilateral decompression is a safe and effective surgical procedure with favorable complication profile and patient outcomes.

Lumbar spinal stenosis is characterized by narrowing of the spinal canal from hypertrophic degenerative changes of surrounding soft and bony tissues.1,9,10,25,27 Given the degenerative nature of these changes, it follows that they are seen at a high rate in older patients, and indeed the LAIDBACK study found that patients 65 years and older had a 100% rate of disc degeneration, 38% rate of facet arthropathy, and 21% rate of moderate to severe central stenosis.22,35 These degenerative changes and the concomitant compression of neural elements may manifest as axial low-back and/or radicular leg pain; symptoms are exacerbated by standing and walking and are commonly referred to as neurogenic claudication. Lumbar spinal stenosis represents the primary indication for spine surgery in patients older than 65 years, with over 37,000 patients in this population undergoing operative intervention in 2007.9,10,36

Open laminectomy for spinal stenosis has been shown to be a safe and cost-effective procedure, with superior outcomes compared to nonsurgical management.3,4,28,31,32,39,40 However, performing adequate bony decompression of neural elements may cause segmental spinal instability, leading to recrudescence of symptoms or subsequent need for arthrodesis.16,23 A recent review of the literature demonstrated the incidence of new or increased postlaminectomy spondylolisthesis to be 5.5%, with 1.8% of patients requiring a reoperation for instability.19 Thus, a recent randomized controlled trial showed that 34% of patients who underwent a traditional laminectomy for lumbar spinal stenosis with stable spinal spondylolisthesis require revision surgery within 4 years of the index surgery.18 Decompressive minimally invasive surgery (MIS) using tubular retractors has been pioneered as a less locally destructive alternative to open laminectomy in order to better preserve the posterior osseoligamentous complex and minimize postdecompression destabilization.1,15,37 Minimally invasive unilateral laminotomy for bilateral decompression (ULBD) results in excellent reduction of scores on the Oswestry Disability Index (ODI), as well as back and leg pain scores, while it is associated with a low complication rate.1,37 The favorable functional outcome following tubular ULBD6 has encouraged the adaptation of this technique for the working-channel endoscope.24,34,38 However, the efficacy and safety of endoscopic ULBD in comparison to the tubular MIS approach has not yet been analyzed in detail.

This study compares the clinical outcomes and complications of patients who underwent ULBD utilizing either a full-endoscopic or tubular MIS approach.

Methods

Patient Selection

All participating patients provided written informed consent prior to under the procedures as detailed. Collection of standard perioperative and postoperative outcome data is routinely done as part of the University of Washington Spine Care Quality Initiative. Our prospectively collected database was retrospectively queried for ULBD performed either with a working-channel endoscope or minimally invasive technique using tubular retractors and the microscope.6 Between September 2014 and February 2017, 95 consecutive procedures were performed at the University of Washington by a single surgeon (C.P.H.). Conservative therapy, including at least 6 weeks of physical therapy, nonsteroidal antiinflammatory drugs, or epidural steroid injections, had failed to resolve symptoms. Patients were excluded if they demonstrated dynamic instability (more than 3 mm motion on flexion/extension radiographs), lumbar scoliosis measuring more than 20° of coronal Cobb angle, primary disc herniation, or a sequestered disc fragment. The choice of minimally invasive versus endoscopic technique was determined by equipment availability rather than surgical preference in cases of one and two-level procedures. Given the longer operative time for endoscopic cases, we favored MIS for 3-level decompressions. We recorded standard patient demographics, preoperative images, surgical details, clinical outcome scores, and complications. Outcomes were quantified using visual analog scale (VAS) and ODI scores12 at 2-week, 3-month and at 1-year follow-up intervals. The minimally clinically important differences (MCIDs) were regarded 12 points, as defined by ODI scoring,5,17,20 and 3 points, as defined by VAS scoring.13,14,20

Preoperative Imaging

All patients included in the current report underwent preoperative flexion and extension radiography of the lumbar spine to rule out dynamic instability. Dynamic instability was defined as more than 3 mm of translational movement in an anteroposterior (AP) direction.26 Preoperative T2-weighted MR images of the lumbar spine were obtained to establish the diagnosis of lumbar spinal stenosis.

Surgical Technique

Positioning and Approach

All patients undergo general anesthesia and are positioned prone on a Jackson table with a Wilson frame. The goal of positioning is to maximize kyphosis of the lumbar spine, which is accomplished by elevating the Wilson frame or placing pads underneath the anterior superior iliac spine. Once the patient is prepared and draped, an AP radiograph is obtained to confirm the appropriate level and determine the optimal craniocaudal approach angle. Tilting the C-arm approximately 10°–15° caudally from an endplate view of the caudal index level vertebral body typically yields the maximum interlaminar window in the lower lumbar segments (Fig. 1). Utilizing the previously ascertained craniocaudal tilt, a skin incision is marked where the inferior aspect of the target lamina intersects with the middle of the disc space (Fig. 1). A stab incision is made through skin and fascia with a no. 11 blade. Serial dilators are advanced until the inferior margin of the lamina is palpated, at which point a final confirmatory AP radiograph is obtained. The tubular retractor is then introduced with the bevel oriented medially. Care must be taken to advance the tubular retractor until the lamina is easily palpated, as failure to maintain solid contact with the bone will cause insufficient retraction of the paraspinal muscles. The trocar is then replaced for the endoscope (ILESSYS delta, Joimax, VERTEBRIS stenosis, Richard Wolfe). The bipolar cautery and micropunches are used to outline the inferior margin of the lamina and the medial extent of the facet joint.

Fig. 1.
Fig. 1.

AP fluoroscopic intraoperative images for approach planning. A: First, an AP endplate view of the superior endplate of the caudal level is obtained (L3–4, arrow). B: The addition of kyphosis of the rostrocaudal radiographic beam angle moves the projection of the interspinous process space toward the disc space (arrowhead). C: An ideal rostrocaudal trajectory has been determined (arrowhead). D: The skin incision is marked at the tip of the radiopaque object. E: A lateral radiograph may be obtained to confirm the level. F: Once the working tube is brought into place, an AP radiograph confirms the location of the working tube at the inferior margin of the lamina (arrow).

Decompression

A high-speed diamond burr is used to remove the inferior portion of the superior lamina, the base of the spinous process, and the medial aspect of the ipsilateral facet (Fig. 2). At this point, the ligamentum flavum is identified and dissected along its fibers using the micropunch (Fig. 3). Once the epidural space is entered, the ligamentum flavum is removed piecemeal with Kerrison rongeurs (Fig. 3). The contralateral lamina and facet joint are undercut using a high-speed burr. Resection of ligamentum flavum and the contralateral medial facetectomy are completed using a Kerrison rongeur reaching from the tip of the superior articular process (SAP) to the middle of the caudal pedicle. The contralateral disc and pedicle are visualized, and complete decompression of the contralateral traversing nerve root is confirmed (Fig. 4).

Fig. 2.
Fig. 2.

As an initial anatomical landmark, the inferior edge of the lamina (lam) is exposed (A). Often the yellow ligament (y) can be seen, too. Following resection of the inferior edge of the lamina with a diamond burr (B), the bony insertion of the yellow ligament can be clearly identified (C). C = caudal; R = rostral; s = base of the spinous process.

Fig. 3.
Fig. 3.

Entering the epidural space. Using a micropunch, the yellow ligament is opened (A). Following opening of the yellow ligament, ample epidural space and epidural fat is noted. Arrow points to the edge of new opening in yellow ligament with dural interface below (B). The opening is widened using Kerrison rongeurs (C).

Fig. 4.
Fig. 4.

Following undercutting of the spinous process, the contralateral inferior articular process (IAP) and SAP forming the posterior wall of the lateral recess become visible (A). Following decompression of the medial aspect of the SAP, the contralateral pedicle (p) and traversing nerve root (arrow) can be inspected (B). C = caudal; R = rostral.

For decompression of the ipsilateral lateral recess, the high-speed diamond burr is employed to undercut the ipsilateral facet until the traversing nerve root is identified. Rotating the endoscope leverages the off-axis aperture and gives the surgeon the ability to directly visualize the nerve root and efficiently undercut the facet joint. At this point, the SAP is identified and resected along the lateral margin of the traversing nerve root (Fig. 5). Once the traversing nerve root is decompressed, it is reflected medially using a blunt dissector. Adhesions can be freed by blunt dissection or cut using scissors or bipolar cautery. The annulus and endplates lying just anterior to the traversing nerve root are visualized. Direct visualization and decompression of the traversing nerve root should be obtained, spanning from the tip of the SAP through the middle of the caudal pedicle.

Fig. 5.
Fig. 5.

Decompression of the traversing nerve root (arrow) within the ipsilateral lateral recess is carried out using a high-speed drill and Kerrison rongeur (A). Inspection of the undercut ipsilateral facet joint. The medial aspect of the IAP has been resected, and the SAP has been undercut from the tip to the midportion of the caudal pedicle (B). Following decompression, direct visualization of the ipsilateral traversing nerve root is achieved (C).

Closure. Hemostasis is achieved within the surgical site, and the endoscope and working channel are then removed. Closure proceeds in multilayered fashion, using 0 Vicryl for subcutaneous tissue, followed by a subcuticular 4-0 Biosyn for the skin. Steri-Strips and a PRIMAPORE dressing are sterilely applied.

Postoperative Care

All patients included in the current study were encouraged to leave the hospital the day of surgery independent on the mode of surgery. Only patients with medical comorbidities requiring close postoperative monitoring or patients older than 70 years were admitted to the hospital for monitoring.

Statistical Analysis

Continuous variables are displayed as means ± SEMs. Independent continuous variables were compared using a t-test. Categorical variables were compared using the chi-square test. A p value of less than 0.05 was considered significant. Statistical calculations were carried out using SPSS 24 for Mac.

Results

Patient Characteristics

Our cohort of 95 patients consisted of 41 females (43.2%) and 54 males (56.8%); the average age was 62 ± 1.3 years. The majority of patients had at least one comorbidity (69.5%), most commonly hypertension (39.0%), hyperlipidemia (25.3%), diabetes mellitus (19.0%), and coronary artery disease (14.7%). The average body mass index (BMI) of our patient cohort was 29.9 ± 0.7 kg/m2. Thus, 43.2% of our patients had a BMI greater than 30 kg/m2 (obese) and half of these greater than 35 kg/m2 (morbidly obese). These patient characteristics did not differ significantly between the MIS and endoscopic patient cohorts (Table 1). The combined patient low-back disability score was 49.4 ± 1.7 (ODI); the VAS score for back pain was 6.5 ± 0.3, and the VAS score for leg pain was 6.2 ± 0.3. These patient-reported characteristics were similar between the MIS and the endoscopic group (Table 2).

TABLE 1.

Patient characteristics

Approach to ULBD
CharacteristicMIS (n = 45)Endoscopic (n = 50)p Value
Female sex18 (40.0%)23 (46.0%)NS
Comorbidities29 (64.4%)36 (72.0%)NS
Obesity (BMI >30)21 (46.7%)20 (40.0%)NS
Prior surgery
Levels of stenosis
 121 (46.7%)32 (64.0%)NS
 217 (37.8%)17 (34.0%)
 ≥37 (15.5%)1 (2.0%)NS
Spondylolisthesis23 (51.1%)20 (40%)NS
Lumbar scoliosis18 (40.0%)27 (54%)NS

NS = not significant.

TABLE 2.

Functional outcome

Approach to ULBD
VariableMIS (n = 45)Endoscopic (n = 50)p Value
Preop score
 ODI47.2 ± 3.151.0 ± 1.9NS
 VAS back7.1 ± 0.46.0 ± 0.4NS
 VAS leg6.3 ± 0.56.2 ± 0.4NS
2-wk score
 ODI40.0 ± 3.033.2 ± 3.3NS
 VAS back4.0 ± 0.44.1 ± 0.4NS
 VAS leg2.3 ± 0.52.7 ± 0.5NS
3-mo score
 ODI28.0 ± 4.425.5 ± 3.3NS
 VAS back4.0 ± 0.63.1 ± 0.4NS
 VAS leg3.3 ± 0.62.4 ± 0.5NS
12-mo score
 ODI35.9 ± 4.120.7 ± 3.4<0.01
 VAS back4.2 ± 0.62.6 ± 0.4<0.05
 VAS leg3.0 ± 0.51.3 ± 0.3<0.01

Scores are presented as the mean ± SEM.

Surgical Details

Our patient cohort consisted of 45 patients who underwent MIS and 50 patients who underwent endoscopic lumbar ULBD. The majority of patients underwent 1-level decompressions and approximately one-third of the patients underwent 2-level decompressions (Table 1). There was a tendency toward fewer 3-level lumbar decompressions in the endoscopic group. Thus, our study reports on a total of 148 lumbar laminotomies for bilateral decompression of lumbar spinal levels, of which 78 were carried out using MIS and 70 using an endoscopic technique. The most commonly treated levels were L4–5 and L3–4. Approximately half of the patients had stable spondylolisthesis at the index level (45.3%). Mild lumbar scoliosis with a coronal Cobb angle of less than 20° was present in 47.4% of all patients. Surgeries were generally well tolerated, and there was no intraoperative morbidity or mortality (Table 3). The surgical time for the endoscopic technique was significantly longer per level compared to MIS (161.8 ± 6.8 minutes vs 99.3 ± 4.6 minutes, p < 0.001). As expected, no learning curve was observed for well-established MIS technique, with stable surgical times during the duration of the study (early half of the MIS cohort [n = 22], 98.1 ± 6.0 minutes; late half of the cohort [n = 23], 100.0 ± 7.0 minutes). In contrast, we found a significant reduction in the surgical time per level in our endoscopic cohort. Thus, for the early half of our study (n = 25), the operative time per level was 179.4 ± 10.4 minutes, while a significant reduction was observed in the second half of the endoscopic patient cohort (n = 25, 144.1 ± 7.4 minutes; p < 0.01). The estimated blood loss was less with endoscopic technique than the MIS; however, this difference was not clinically significant. Hospital stay for MIS patients was on average 2.4 ± 0.5 days, compared to 0.7 ± 0.1 days for endoscopic patients (p = 0.001). Two patients in the MIS group required return to the operating room acutely after surgery (< 14 days) for epidural hematomas causing neurological deficits. Evacuation of the hematomas was accomplished using an MIS technique, and neurological deficits resolved. One patient in the endoscopic group suffered from an acute disc herniation at the index level and also required an acute discectomy, which was carried out using full-endoscopic technique. Three patients (6.7%) in the MIS group had durotomies that were repaired with on-lay DuraGen followed by TISSEEL and led to no further clinical sequelae. Six patients (13.3%) in the MIS group had transient postoperative urinary retention requiring intermittent catheterization. Three patients (6%) in the full-endoscopic cohort developed transient postoperative lower-extremity paresthesias, while only one patient (2.2%) suffered from this complication in the MIS cohort. Thus, patients who underwent MIS ULBD had a statistically significant higher rate of complications (26.7%) compared to patients who underwent endoscopic procedures (8.0%) (p < 0.05). We did not detect a significant learning curve regarding complications, as the rate of complications did not differ between the first and second halves of the cohort in either treatment group. During the 1-year follow-up, 4 patients exhibited symptoms from additional pathology at the index level and underwent surgery for the following pathologies: foraminal stenosis (n = 2), disc herniation (n = 1), and synovial cyst (n = 1). None of these revision surgeries required an arthrodesis construct.

TABLE 3.

Surgical details

Approach to ULBD
VariableMIS (n = 45)Endoscopic (n = 50)p Value
Op time (mins)*154.1 ± 6.2210.8 ± 9.7<0.001
EBL (ml)*51.8 ± 11.06.5 ± 0.6NCS
Hospital stay (days)*2.4 ± 0.50.7 ± 0.10.001
Acute postop complication(s)Epidural hematoma (n = 2), durotomy (n = 3), urinary retention (n = 6), paresthesias (n = 1)Disc herniation (n =1), paresthesias (n =3)<0.05
Index-level additional surgery indicationForaminal stenosis (n = 1)Foraminal stenosis (n = 1), disc herniation (n = 1), synovial cyst (n = 1)NS

EBL = estimated blood loss; NCS = not clinically significant.

Values are presented as the mean ± SEM.

Functional Outcomes and Complications

Follow-up data were available for 94.7% of patients in our current cohort (5 patients were lost to follow-up). At the 1-year follow-up, approximately half of the patients achieved an MCID on the VAS for back pain (52.6% of the endoscopic cohort; 51.4% of the MIS cohort). At last follow-up, the average VAS score for back pain was significantly lower in endoscopic patients than in MIS patients (2.6 ± 0.4 vs 4.2 ± 0.6, respectively; p < 0.05) (Table 2). A minimally clinically important improvement of the VAS score for leg pain was detected in 62.9% of patients undergoing MIS compared to 76.3% undergoing endoscopic procedures. On average, endoscopic patients had significantly less leg pain than MIS patients (1.3 ± 0.3 vs 3.0 ± 0.5, respectively; p < 0.01). Similarly, 58.8% of MIS patients achieved a minimally clinically important improvement of their back pain disability index (ODI) compared to 73.7% in the endoscopic cohort. Thus, at the 1-year follow-up, the mean back pain disability index score was significantly lower in the full-endoscopic than the MIS cohort (20.7 ± 3.4 vs 35.9 ± 4.1, respectively; p < 0.01).

Discussion

Lumbar spinal stenosis is one of the most common indications for spinal surgery across all patient demographics and is the most common indication for spinal surgery in the elderly. Surgical decompression has been shown to be a safe and effective treatment for symptomatic lumbar spinal stenosis in a multitude of studies, regardless of whether traditional or MIS technique is utilized or whether it is combined with arthrodesis.3,4,28,31,32,39,40 However, recent studies have demonstrated rates of postlaminectomy spondylolisthesis of up to 5.5% with nearly 2% of patients requiring subsequent fusion.19 Growing recognition of this problem has been addressed with two divergent approaches intended to reduce the rate of reoperation for postlaminectomy instability.

The first trend is one in which growing awareness of postlaminectomy spondylolisthesis is driving an increasing number of arthrodesis procedures being performed upfront for lumbar spinal stenosis. Unfortunately, the increased complexity of arthrodesis procedures results in increased costs, complications, and a potentially higher rate of reoperations.

The second trend, driven by the same impetus, has been a shift toward the development, evaluation, and implementation of minimally invasive approaches to the spine, with the goal of sparing stabilizing osseoligamentous structures from unnecessary resection during decompression. Minimally invasive tubular approaches have been successfully adopted as an alternative to open laminectomy; they are less locally destructive and have indeed been shown to result in better preservation of posterior osseoligamentous structures, with reduced rates of postlaminectomy destabilization.1,8,11,15,33,37 Encouraging clinical results and patient demand have resulted in widespread adoption of the minimally invasive tubular approach despite a significant learning curve. They have also spurred the development of novel working-channel endoscope–based approaches that optimize the surgeon’s ability to visualize target pathology and intervene as precisely as possible with minimal disruption of stabilizing structures.

The traditional laminectomy approach requires a wide decompression in conjunction with undercutting of the overhanging facet joints, which may lead to joint instability and subsequent spondylolisthesis and scoliosis.29 Accordingly, biomechanical studies have revealed the essential role of the facet joint in constraint of axial rotation and flexion, as well as the direct relationship between the extent of facet resection and the degree of joint destabilization.21,30 We hypothesize that the utilization of working channel endoscopes enables a higher-precision surgical approach that enables surgeons to unambiguously visualize and confirm their decompression of neural elements within the lateral recess, while sparing as much facet joint as possible. In comparison, the minimally invasive technique with a 20-mm-diameter working channel and a 300-mm-working-distance microscope frequently does not allow for illumination and visualization of the neural elements in the ipsilateral lateral recess without requiring significant resection of the facet joint. Thus, minimally invasive decompression of the ipsilateral lateral recess is frequently carried out utilizing up-angled curettes or foraminal Kerrison rongeurs without direct visualization of neural elements. Further studies need to be conducted to confirm whether more thorough lateral recess decompression with the endoscope may contribute to the better clinical outcomes attained compared to outcomes obtained with minimally invasive ULBD. Moreover, further studies will also need to evaluate the rate of dynamic instability at the index level following endoscopic ULBD compared to more traditional techniques.

Tubular and endoscopic minimally invasive techniques have both been utilized for laminotomies for bilateral decompression, but the approaches have not previously been directly compared. Tubular minimally invasive decompression allows the surgeon to utilize large footprint tools, which may allow for a faster decompression, especially when augmented by 3D visualization of the operative microscope. However, the efficiency may come at the cost of increased manipulation of the thecal sac and destruction of clinically significant osseoligamentous structures. In comparison, endoscopy affords a 15° off-axis view with constant irrigation, which provides continuous high-definition visualization of the neural elements within the lateral recesses around the spared facet joints. One limitation of the full-endoscopic approach is the smaller tools that are required for compatibility with the narrow working channel, which contributes to increased total duration of surgery. In addition, 2D visualization through the endoscope limits depth perception, hobbles hand-eye coordination, and results in poorer estimation of the size at varying depths of the field of view.3,9

Patients who underwent tubular minimally invasive decompression in our study achieved a mean VAS leg pain scores (3.0 ± 0.5) comparable with the range published in the literature at ≥ 1 year of follow-up (range 0–4.2).2,7,37 The ODI score in our MIS group was reduced by 11.3, with 58.8% of these patients achieving an MICD for ODI score. This is comparable with previously reported outcomes after minimally invasive ULBD (ODI reductions of 16.31 and 17.27; proportion of MICD 54.8%1). Therefore, we are confident that outcomes from our tubular decompressive MIS represent an appropriate reference for comparison to the endoscopic decompression cohort.

In general, we believe that our findings demonstrate that both MIS tubular and endoscopic approaches are safe and effective for the treatment of lumbar spinal stenosis. Minimally invasive decompression is more efficiently carried out in the OR but may be associated with a higher rate of complications and less functional improvement than endoscopic decompression. The endoscopic technique has a steep learning curve, requires specialized equipment, demands more time in the OR, and has not yet been established as a routine surgical approach.

Our study is intended to provide the spine surgeon with a detailed description of the surgical technique and representative midterm clinical outcomes. However, we acknowledge that our study has several limitations. While our cohorts were well matched regarding preoperative disability and pain scores, there was a tendency toward a higher proportion of 3-level decompressions in the MIS cohort. Importantly, analysis of VAS scores for back and leg pain, as well as ODI scores in 1- and 2-level decompression groups, confirmed favorable outcomes 1 year following endoscopic compared to minimally invasive procedures (2.7 ± 0.4 vs 4.5 ± 0.6, p < 0.05; 1.3 ± 0.3 vs 3.1 ± 0.5, p < 0.01; and 21.1 ± 3.4 vs 37.8 ± 4.4, p < 0.01; for VAS back, VAS leg, ODI score, respectively). Superior VAS leg scores likely reflect the targeted decompression that direct visualization with the endoscope affords the surgeon. Nevertheless, further studies are necessary to evaluate whether the superior clinical outcomes achieved in the endoscopic group prove to be durable over the long term. Additional study is required to analyze the effect of the endoscopic approach on clinical and radiographic development of spondylolisthesis.

Conclusions

In summary, both the minimally invasive tubular and full-endoscopic approaches for ULBD achieve good patient outcomes with acceptable rates of perioperative complications. In our patient cohort, full-endoscopic technique was associated with significantly longer operative times, reduced hospital length of stay, and superior clinical outcomes at 1 year compared to MIS. Further efforts are necessary to refine, define, and teach endoscopic surgical techniques in order to establish endoscopic spine surgery as a safe, well-defined, and standardized technique for our patients.

Disclosures

Dr. Hofstetter reports being a consultant for J&J, Globus, and Joimax.

Author Contributions

Conception and design: Hofstetter, McGrath. Acquisition of data: all authors. Analysis and interpretation of data: all authors. Drafting the article: all authors. Critically revising the article: Hofstetter, McGrath. Reviewed submitted version of manuscript: Hofstetter, McGrath. Approved the final version of the manuscript on behalf of all authors: Hofstetter. Statistical analysis: Hofstetter, McGrath. Administrative/technical/material support: Hofstetter, McGrath. Study supervision: Hofstetter, McGrath.

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    • Export Citation
  • 8

    Dasenbrock HH, Juraschek SP, Schultz LR, Witham TF, Sciubba DM, Wolinsky JP, et al.: The efficacy of minimally invasive discectomy compared with open discectomy: a meta-analysis of prospective randomized controlled trials. J Neurosurg Spine 16:452462, 2012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Deyo RA, Mirza SK, Martin BI: Back pain prevalence and visit rates: estimates from U.S. national surveys, 2002. Spine (Phila Pa 1976) 31:27242727, 2006

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Deyo RA, Mirza SK, Martin BI, Kreuter W, Goodman DC, Jarvik JG: Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. JAMA 303:12591265, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Evins AI, Banu MA, Njoku I Jr, Elowitz EH, Härtl R, Bernado A, et al.: Endoscopic lumbar foraminotomy. J Clin Neurosci 22:730734, 2015

  • 12

    Fairbank JC, Pynsent PB: The Oswestry Disability Index. Spine (Phila Pa 1976) 25:29402952, 2000

  • 13

    Farrar JT, Portenoy RK, Berlin JA, Kinman JL, Strom BL: Defining the clinically important difference in pain outcome measures. Pain 88:287294, 2000

  • 14

    Farrar JT, Young JP Jr, LaMoreaux L, Werth JL, Poole RM: Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale. Pain 94:149158, 2001

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Foley KT, Smith MM, Rampersaud YR: Microendoscopic approach to far-lateral lumbar disc herniation. Neurosurg Focus 7(5):e5, 1999

  • 16

    Fox MW, Onofrio BM, Onofrio BM, Hanssen AD: Clinical outcomes and radiological instability following decompressive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone. J Neurosurg 85:793802, 1996

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Fritzell P, Hägg O, Nordwall A: Complications in lumbar fusion surgery for chronic low back pain: comparison of three surgical techniques used in a prospective randomized study. A report from the Swedish Lumbar Spine Study Group. Eur Spine J 12:178189, 2003

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Ghogawala Z, Dziura J, Butler WE, Dai F, Terrin N, Magge SN, et al.: Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis. N Engl J Med 374:14241434, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Guha D, Heary RF, Shamji MF: Iatrogenic spondylolisthesis following laminectomy for degenerative lumbar stenosis: systematic review and current concepts. Neurosurg Focus 39(4):E9, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Hägg O, Fritzell P, Ekselius L, Nordwall A: Predictors of outcome in fusion surgery for chronic low back pain. A report from the Swedish Lumbar Spine Study. Eur Spine J 12:2233, 2003

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Hasegawa K, Kitahara K, Shimoda H, Hara T: Facet joint opening in lumbar degenerative diseases indicating segmental instability. J Neurosurg Spine 12:687693, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Jarvik JJ, Hollingworth W, Heagerty P, Haynor DR, Deyo RA: The Longitudinal Assessment of Imaging and Disability of the Back (LAIDBack) Study: baseline data. Spine (Phila Pa 1976) 26:11581166, 2001

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Jönsson B, Annertz M, Sjöberg C, Strömqvist B: A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part II: Five-year follow-up by an independent observer. Spine (Phila Pa 1976) 22:29382944, 1997

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Komp M, Hahn P, Oezdemir S, Giannakopoulos A, Heikenfeld R, Kasch R, et al.: Bilateral spinal decompression of lumbar central stenosis with the full-endoscopic interlaminar versus microsurgical laminotomy technique: a prospective, randomized, controlled study. Pain Physician 18:6170, 2015

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Kreiner DS, Shaffer WO, Baisden JL, Gilbert TJ, Summers JT, Toton JF, et al.: An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spinal stenosis (update). Spine J 13:734743, 2013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26

    Leone A, Guglielmi G, Cassar-Pullicino VN, Bonomo L: Lumbar intervertebral instability: a review. Radiology 245:6277, 2007

  • 27

    Machado GC, Ferreira PH, Yoo RI, Harris IA, Pinheiro MB, Koes BW, et al.: Surgical options for lumbar spinal stenosis. Cochrane Database Syst Rev 11:CD012421, 2016

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Malmivaara A, Slätis P, Heliövaara M, Sainio P, Kinnunen H, Kankare J, et al.: Surgical or nonoperative treatment for lumbar spinal stenosis? A randomized controlled trial. Spine (Phila Pa 1976) 32:18, 2007

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Overdevest G, Vleggeert-Lankamp C, Jacobs W, Thomé C, Gunzburg R, Peul W: Effectiveness of posterior decompression techniques compared with conventional laminectomy for lumbar stenosis. Eur Spine J 24:22442263, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Panjabi MM: Clinical spinal instability and low back pain. J Electromyogr Kinesiol 13:371379, 2003

  • 31

    Parker SL, Fulchiero EC, Davis BJ, Adogwa O, Aaronson OS, Cheng JS, et al.: Cost-effectiveness of multilevel hemilaminectomy for lumbar stenosis-associated radiculopathy. Spine J 11:705711, 2011

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Parker SL, Godil SS, Mendenhall SK, Zuckerman SL, Shau DN, McGirt MJ: Two-year comprehensive medical management of degenerative lumbar spine disease (lumbar spondylolisthesis, stenosis, or disc herniation): a value analysis of cost, pain, disability, and quality of life: clinical article. J Neurosurg Spine 21:143149, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Perez-Cruet MJ, Foley KT, Isaacs RE, Rice-Wyllie L, Wellington R, Smith MM, et al.: Microendoscopic lumbar discectomy: technical note. Neurosurgery 51 (5 Suppl):S129S136, 2002

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Ruetten S, Komp M, Merk H, Godolias G: Surgical treatment for lumbar lateral recess stenosis with the full-endoscopic interlaminar approach versus conventional microsurgical technique: a prospective, randomized, controlled study. J Neurosurg Spine 10:476485, 2009

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Suri P, Boyko EJ, Goldberg J, Forsberg CW, Jarvik JG: Longitudinal associations between incident lumbar spine MRI findings and chronic low back pain or radicular symptoms: retrospective analysis of data from the longitudinal assessment of imaging and disability of the back (LAIDBACK). BMC Musculoskelet Disord 15:152, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 36

    Taylor WR, Chen JW, Meltzer H, Gennarelli TA, Kelbch C, Knowlton S, et al.: Quantitative pupillometry, a new technology: normative data and preliminary observations in patients with acute head injury. Technical note. J Neurosurg 98:205213, 2003

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Thomé C, Zevgaridis D, Leheta O, Bäzner H, Pöckler-Schöniger C, Wöhrle J, et al.: Outcome after less-invasive decompression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminectomy. J Neurosurg Spine 3:129141, 2005

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Wagner SC, Butler JS, Kaye ID, Sebastian AS, Morrissey PB, Kepler CK: Risk factors for and complications after surgical delay in elective single-level lumbar fusion. Spine (Phila Pa 1976) 43:228233, 2018

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 39

    Weinstein JN, Tosteson TD, Lurie JD, Tosteson AN, Blood E, Hanscom B, et al.: Surgical versus nonsurgical therapy for lumbar spinal stenosis. N Engl J Med 358:794810, 2008

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Wilby MJ, Seeley H, Laing RJ: Laminectomy for lumbar canal stenosis: a safe and effective treatment. Br J Neurosurg 20:391395, 2006

  • Collapse
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Multidisciplinary surgical planning for a patient with myxoid liposarcoma extending from C4 to T1. See the article by Ahmed et al. (pp 424–431).

  • AP fluoroscopic intraoperative images for approach planning. A: First, an AP endplate view of the superior endplate of the caudal level is obtained (L3–4, arrow). B: The addition of kyphosis of the rostrocaudal radiographic beam angle moves the projection of the interspinous process space toward the disc space (arrowhead). C: An ideal rostrocaudal trajectory has been determined (arrowhead). D: The skin incision is marked at the tip of the radiopaque object. E: A lateral radiograph may be obtained to confirm the level. F: Once the working tube is brought into place, an AP radiograph confirms the location of the working tube at the inferior margin of the lamina (arrow).

  • As an initial anatomical landmark, the inferior edge of the lamina (lam) is exposed (A). Often the yellow ligament (y) can be seen, too. Following resection of the inferior edge of the lamina with a diamond burr (B), the bony insertion of the yellow ligament can be clearly identified (C). C = caudal; R = rostral; s = base of the spinous process.

  • Entering the epidural space. Using a micropunch, the yellow ligament is opened (A). Following opening of the yellow ligament, ample epidural space and epidural fat is noted. Arrow points to the edge of new opening in yellow ligament with dural interface below (B). The opening is widened using Kerrison rongeurs (C).

  • Following undercutting of the spinous process, the contralateral inferior articular process (IAP) and SAP forming the posterior wall of the lateral recess become visible (A). Following decompression of the medial aspect of the SAP, the contralateral pedicle (p) and traversing nerve root (arrow) can be inspected (B). C = caudal; R = rostral.

  • Decompression of the traversing nerve root (arrow) within the ipsilateral lateral recess is carried out using a high-speed drill and Kerrison rongeur (A). Inspection of the undercut ipsilateral facet joint. The medial aspect of the IAP has been resected, and the SAP has been undercut from the tip to the midportion of the caudal pedicle (B). Following decompression, direct visualization of the ipsilateral traversing nerve root is achieved (C).

  • 1

    Alimi M, Hofstetter CP, Pyo SY, Paulo D, Härtl R: Minimally invasive laminectomy for lumbar spinal stenosis in patients with and without preoperative spondylolisthesis: clinical outcome and reoperation rates. J Neurosurg Spine 22:339352, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Alimi M, Hofstetter CP, Torres-Campa JM, Navarro-Ramirez R, Cong GT, Njoku I Jr, et al.: Unilateral tubular approach for bilateral laminotomy: effect on ipsilateral and contralateral buttock and leg pain. Eur Spine J 26:389396, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Atlas SJ, Keller RB, Robson D, Deyo RA, Singer DE: Surgical and nonsurgical management of lumbar spinal stenosis: four-year outcomes from the maine lumbar spine study. Spine (Phila Pa 1976) 25:556562, 2000

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Atlas SJ, Keller RB, Wu YA, Deyo RA, Singer DE: Long-term outcomes of surgical and nonsurgical management of lumbar spinal stenosis: 8 to 10 year results from the Maine Lumbar Spine Study. Spine (Phila Pa 1976) 30:936943, 2005

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Beurskens AJ, de Vet HC, Köke AJ, van der Heijden GJ, Knipschild PG: Measuring the functional status of patients with low back pain. Assessment of the quality of four disease-specific questionnaires. Spine (Phila Pa 1976) 20:10171028, 1995

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Boukebir MA, Berlin CD, Navarro-Ramirez R, Heiland T, Schöller K, Rawanduzy C, et al.: Ten-step minimally invasive spine lumbar decompression and dural repair through tubular retractors. Oper Neurosurg (Hagerstown) 13:232245, 2017

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Costa F, Sassi M, Cardia A, Ortolina A, De Santis A, Luccarell G, et al.: Degenerative lumbar spinal stenosis: analysis of results in a series of 374 patients treated with unilateral laminotomy for bilateral microdecompression. J Neurosurg Spine 7:579586, 2007

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Dasenbrock HH, Juraschek SP, Schultz LR, Witham TF, Sciubba DM, Wolinsky JP, et al.: The efficacy of minimally invasive discectomy compared with open discectomy: a meta-analysis of prospective randomized controlled trials. J Neurosurg Spine 16:452462, 2012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Deyo RA, Mirza SK, Martin BI: Back pain prevalence and visit rates: estimates from U.S. national surveys, 2002. Spine (Phila Pa 1976) 31:27242727, 2006

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Deyo RA, Mirza SK, Martin BI, Kreuter W, Goodman DC, Jarvik JG: Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. JAMA 303:12591265, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Evins AI, Banu MA, Njoku I Jr, Elowitz EH, Härtl R, Bernado A, et al.: Endoscopic lumbar foraminotomy. J Clin Neurosci 22:730734, 2015

  • 12

    Fairbank JC, Pynsent PB: The Oswestry Disability Index. Spine (Phila Pa 1976) 25:29402952, 2000

  • 13

    Farrar JT, Portenoy RK, Berlin JA, Kinman JL, Strom BL: Defining the clinically important difference in pain outcome measures. Pain 88:287294, 2000

  • 14

    Farrar JT, Young JP Jr, LaMoreaux L, Werth JL, Poole RM: Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale. Pain 94:149158, 2001

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Foley KT, Smith MM, Rampersaud YR: Microendoscopic approach to far-lateral lumbar disc herniation. Neurosurg Focus 7(5):e5, 1999

  • 16

    Fox MW, Onofrio BM, Onofrio BM, Hanssen AD: Clinical outcomes and radiological instability following decompressive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone. J Neurosurg 85:793802, 1996

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Fritzell P, Hägg O, Nordwall A: Complications in lumbar fusion surgery for chronic low back pain: comparison of three surgical techniques used in a prospective randomized study. A report from the Swedish Lumbar Spine Study Group. Eur Spine J 12:178189, 2003

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Ghogawala Z, Dziura J, Butler WE, Dai F, Terrin N, Magge SN, et al.: Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis. N Engl J Med 374:14241434, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Guha D, Heary RF, Shamji MF: Iatrogenic spondylolisthesis following laminectomy for degenerative lumbar stenosis: systematic review and current concepts. Neurosurg Focus 39(4):E9, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Hägg O, Fritzell P, Ekselius L, Nordwall A: Predictors of outcome in fusion surgery for chronic low back pain. A report from the Swedish Lumbar Spine Study. Eur Spine J 12:2233, 2003

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Hasegawa K, Kitahara K, Shimoda H, Hara T: Facet joint opening in lumbar degenerative diseases indicating segmental instability. J Neurosurg Spine 12:687693, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Jarvik JJ, Hollingworth W, Heagerty P, Haynor DR, Deyo RA: The Longitudinal Assessment of Imaging and Disability of the Back (LAIDBack) Study: baseline data. Spine (Phila Pa 1976) 26:11581166, 2001

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Jönsson B, Annertz M, Sjöberg C, Strömqvist B: A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part II: Five-year follow-up by an independent observer. Spine (Phila Pa 1976) 22:29382944, 1997

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Komp M, Hahn P, Oezdemir S, Giannakopoulos A, Heikenfeld R, Kasch R, et al.: Bilateral spinal decompression of lumbar central stenosis with the full-endoscopic interlaminar versus microsurgical laminotomy technique: a prospective, randomized, controlled study. Pain Physician 18:6170, 2015

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Kreiner DS, Shaffer WO, Baisden JL, Gilbert TJ, Summers JT, Toton JF, et al.: An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spinal stenosis (update). Spine J 13:734743, 2013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26

    Leone A, Guglielmi G, Cassar-Pullicino VN, Bonomo L: Lumbar intervertebral instability: a review. Radiology 245:6277, 2007

  • 27

    Machado GC, Ferreira PH, Yoo RI, Harris IA, Pinheiro MB, Koes BW, et al.: Surgical options for lumbar spinal stenosis. Cochrane Database Syst Rev 11:CD012421, 2016

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Malmivaara A, Slätis P, Heliövaara M, Sainio P, Kinnunen H, Kankare J, et al.: Surgical or nonoperative treatment for lumbar spinal stenosis? A randomized controlled trial. Spine (Phila Pa 1976) 32:18, 2007

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Overdevest G, Vleggeert-Lankamp C, Jacobs W, Thomé C, Gunzburg R, Peul W: Effectiveness of posterior decompression techniques compared with conventional laminectomy for lumbar stenosis. Eur Spine J 24:22442263, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Panjabi MM: Clinical spinal instability and low back pain. J Electromyogr Kinesiol 13:371379, 2003

  • 31

    Parker SL, Fulchiero EC, Davis BJ, Adogwa O, Aaronson OS, Cheng JS, et al.: Cost-effectiveness of multilevel hemilaminectomy for lumbar stenosis-associated radiculopathy. Spine J 11:705711, 2011

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Parker SL, Godil SS, Mendenhall SK, Zuckerman SL, Shau DN, McGirt MJ: Two-year comprehensive medical management of degenerative lumbar spine disease (lumbar spondylolisthesis, stenosis, or disc herniation): a value analysis of cost, pain, disability, and quality of life: clinical article. J Neurosurg Spine 21:143149, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Perez-Cruet MJ, Foley KT, Isaacs RE, Rice-Wyllie L, Wellington R, Smith MM, et al.: Microendoscopic lumbar discectomy: technical note. Neurosurgery 51 (5 Suppl):S129S136, 2002

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Ruetten S, Komp M, Merk H, Godolias G: Surgical treatment for lumbar lateral recess stenosis with the full-endoscopic interlaminar approach versus conventional microsurgical technique: a prospective, randomized, controlled study. J Neurosurg Spine 10:476485, 2009

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Suri P, Boyko EJ, Goldberg J, Forsberg CW, Jarvik JG: Longitudinal associations between incident lumbar spine MRI findings and chronic low back pain or radicular symptoms: retrospective analysis of data from the longitudinal assessment of imaging and disability of the back (LAIDBACK). BMC Musculoskelet Disord 15:152, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 36

    Taylor WR, Chen JW, Meltzer H, Gennarelli TA, Kelbch C, Knowlton S, et al.: Quantitative pupillometry, a new technology: normative data and preliminary observations in patients with acute head injury. Technical note. J Neurosurg 98:205213, 2003

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Thomé C, Zevgaridis D, Leheta O, Bäzner H, Pöckler-Schöniger C, Wöhrle J, et al.: Outcome after less-invasive decompression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminectomy. J Neurosurg Spine 3:129141, 2005

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Wagner SC, Butler JS, Kaye ID, Sebastian AS, Morrissey PB, Kepler CK: Risk factors for and complications after surgical delay in elective single-level lumbar fusion. Spine (Phila Pa 1976) 43:228233, 2018

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 39

    Weinstein JN, Tosteson TD, Lurie JD, Tosteson AN, Blood E, Hanscom B, et al.: Surgical versus nonsurgical therapy for lumbar spinal stenosis. N Engl J Med 358:794810, 2008

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Wilby MJ, Seeley H, Laing RJ: Laminectomy for lumbar canal stenosis: a safe and effective treatment. Br J Neurosurg 20:391395, 2006

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