Endoscopic posterior decompression under local anesthesia for degenerative lumbar spinal stenosis

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OBJECTIVE

Various minimally invasive techniques have been described for the decompression of lumbar spinal stenosis (LSS). However, few reports have described the results of endoscopic posterior decompression (EPD) with laminectomy performed under local anesthesia. This study aimed to evaluate the clinical and radiological outcomes of EPD performed under local anesthesia in patients with LSS and to compare the procedural outcomes in patients with and without preoperative spondylolisthesis.

METHODS

Fifty patients (28 female and 22 male) who underwent EPD under local anesthesia were included in this study. Patients were assessed before surgery and were followed up with regular outpatient visits (at 1, 3, 6, 12, and 24 months postoperatively). Clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and the 36-Item Short Form Survey (SF-36) outcome questionnaire. Radiological outcomes were assessed by measuring lumbar lordosis, disc-wedging angle, percentage of vertebral slippage, and disc height index on plain standing radiographs.

RESULTS

The VAS, ODI, and SF-36 scores were significantly improved at 1 month after surgery compared to the baseline mean values, and the improved scores were maintained over the 2-year follow-up period. Radiological progression was found in 2 patients during the follow-up period. Patients with and without preoperative spondylolisthesis had no significant differences in their clinical and radiological outcomes.

CONCLUSIONS

EPD performed under local anesthesia is effective for LSS treatment. Similar favorable outcomes can be obtained in patients with and without preoperative spondylolisthesis using this approach.

ABBREVIATIONS DHI = disc height index; EPD = endoscopic posterior decompression; LL = lumbar lordosis; LSS = lumbar spinal stenosis; ODI = Oswestry Disability Index; VAS = visual analog scale.

Abstract

OBJECTIVE

Various minimally invasive techniques have been described for the decompression of lumbar spinal stenosis (LSS). However, few reports have described the results of endoscopic posterior decompression (EPD) with laminectomy performed under local anesthesia. This study aimed to evaluate the clinical and radiological outcomes of EPD performed under local anesthesia in patients with LSS and to compare the procedural outcomes in patients with and without preoperative spondylolisthesis.

METHODS

Fifty patients (28 female and 22 male) who underwent EPD under local anesthesia were included in this study. Patients were assessed before surgery and were followed up with regular outpatient visits (at 1, 3, 6, 12, and 24 months postoperatively). Clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and the 36-Item Short Form Survey (SF-36) outcome questionnaire. Radiological outcomes were assessed by measuring lumbar lordosis, disc-wedging angle, percentage of vertebral slippage, and disc height index on plain standing radiographs.

RESULTS

The VAS, ODI, and SF-36 scores were significantly improved at 1 month after surgery compared to the baseline mean values, and the improved scores were maintained over the 2-year follow-up period. Radiological progression was found in 2 patients during the follow-up period. Patients with and without preoperative spondylolisthesis had no significant differences in their clinical and radiological outcomes.

CONCLUSIONS

EPD performed under local anesthesia is effective for LSS treatment. Similar favorable outcomes can be obtained in patients with and without preoperative spondylolisthesis using this approach.

Symptomatic lumbar spinal stenosis (LSS) unresponsive to conservative treatment is commonly treated with direct surgical decompression. Conventional open laminectomy has been shown to be an effective procedure for the decompression of LSS.10,14 The classic procedure involves the sequential dissection of the paraspinal muscles, facet joints, and spinous processes. However, the resection of these structures may promote postoperative lumbar instability. Furthermore, laminectomy in the presence of preexisting spondylolisthesis is associated with a high rate of subsequent instability requiring fusion surgery.2,5,6 Several endoscopic decompression techniques for LSS, performed under general anesthesia, have been introduced to spare the normal spinal structures.8,9,11,13 Avoiding general anesthesia can reduce the rate of anesthesia-related morbidity and side effects. We performed an endoscopic posterior decompression (EPD) procedure under local anesthesia for the treatment of LSS. The purpose of this study was mainly twofold: to evaluate the clinical and radiological outcomes of EPD for patients with LSS and to compare the outcomes between patients with or without preoperative stable spondylolisthesis.

Methods

Between January 2014 and May 2015, EPD was performed in 57 consecutive patients. The inclusion criterion for this study was neurogenic claudication or radiculopathy symptoms accompanied by moderate to severe LSS, with or without mild spondylolisthesis (Meyerding grade I). Patients with obvious instabilities, spondylolisthesis greater than Meyerding grade II, severe foraminal stenosis, and mainly back pain symptoms were excluded. In addition, patients with a history of any spinal surgery, posttraumatic kyphosis, multilevel lumbar spinal stenosis exceeding 3 levels, and spinal deformities such as lumbar degenerative kyphosis were excluded.

We classified 57 patients into two groups based on accompanying mild spondylolisthesis. Twenty-five patients had accompanying spondylolisthesis (group 2) and 32 patients did not (group 1). Of 57 patients, 5 in group 1 and 2 in group 2 were withdrawn from the study for reasons described in Fig. 1. Of these 7 excluded patients, 2 in group 1 and 1 in group 2 did not satisfy the 2-year follow-up inclusion criterion because of additional surgery for postoperative complications. Two patients underwent revision fusion surgery at another hospital, and 1 patient underwent revision microscopic decompression surgery at our hospital for postoperative epidural hematoma. The remaining 4 patients were lost to follow-up because they did not visit the hospital, despite our phone request for the postoperative follow-up. Finally, 50 patients were analyzed in this study. Of these, 27 were in group 1 and 23 were in group 2. The mean age at the time of surgery was 65.6 years (range 52–82 years; group 1: 66.5 ± 5.4 years, group 2: 64.2 ± 6.5 years), and 28 and 22 patients were female and male, respectively. In 5 patients, the surgery was performed at two intervertebral levels (L3–4 and L4–5 in 3 cases and L4–5 and L5–S1 in 2 cases; 3 in group 1 and 2 in group 2), while 45 patients had single-level surgery (L3–4 in 2 cases, L4–5 in 41 cases, and L5–S1 in 2 cases).

Fig. 1.
Fig. 1.

Flowchart of patient enrollment in the study.

The patients underwent relevant clinical and radiological investigations and follow-up for up to 2 years. The data of the 50 patients who underwent EPD were retrospectively reviewed. All patients underwent continuous conservative treatment including medication, physical therapy, and selective nerve root block therapy for a minimum of 6 weeks before the procedure. All patients’ clinical parameters were assessed before surgery, and patients were followed up with regular outpatient visits at 1, 3, 6, 12, and 24 months postoperatively. In addition, all patients underwent radiological assessment (plain radiography and CT scanning) before surgery and at 1 and 2 years postoperatively. This study was approved by the Clinical Research Ethics Committee of Pusan National University Hospital. Informed consent was waived because of the retrospective nature of the study.

Surgical Technique

The entirety of the EPD procedure was performed with the patient under local anesthesia and conscious sedation. As premedication, midazolam (0.05 mg/kg) was injected intramuscularly 30 minutes before the surgery. Dexmedetomidine (loading dose 1 mg/kg over 10 minutes; maintenance dose 0.2–0.7 mg/kg/hour) was intravenously administered during the surgery. The patient was placed in the prone position on a radiolucent table. The skin entry point was located about 1–2 cm lateral to the midline (depending on the patient’s waist size, interlaminar space width, and facet joint location), and local anesthesia was administered to the skin and facet joint. A tapered obturator was inserted into the interlaminar window under the fluoroscopic control. After the obturator was correctly placed on the ligamentum flavum in the interlaminar window, a beveled working cannula was introduced over the obturator. After the obturator was withdrawn, an endoscope was inserted. Initially, the surgeon could view the surface of the ligamentum flavum via the endoscopic visualization. The decompression was performed by starting with an ipsilateral partial laminectomy and medial facetectomy using an endoscopic cutting burr (from a cranial to caudal direction) until the edge of the deep part of the ligamentum flavum was exposed. After ipsilateral decompression, it was necessary to resect the base of the spinous process using the endoscopic cutting burr and osteotome. Because the base of the spinous process usually obstructs the endoscope placement, a partial spinous process resection was necessary, in some cases, to create a sufficient working space. The entry to the contralateral side was performed dorsal to the dura. The ligamentum flavum was initially left intact to protect the dura. Contralateral bony decompression was performed between the undersurface of the lamina and the ligamentum flavum using an endoscopic Kerrison punch, a cutting burr, and a diamond burr. After the complete resection of the ligamentum flavum, a foraminotomy was performed using the endoscopic Kerrison punch (Fig. 2). The adequacy of the decompression was determined by probing both traversing nerve roots and by examining the extent of the medial facetectomy. After all the instruments were removed, a drain was inserted if necessary, depending on the amount of intraoperative bleeding, and it was kept in place for 1 day postoperatively. The extent of the decompression was evaluated in all patients by comparing the preoperative MRI findings to those obtained 1 day postoperatively (Fig. 3). Patients were discharged within 7 days of surgery and were prescribed a back brace to wear for 2 weeks.

Fig. 2.
Fig. 2.

An illustration of the surgical decompression technique. Copyright Jung Sub Lee. Published with permission.

Fig. 3.
Fig. 3.

A: Preoperative axial T2-weighted MR image of the lumbar spine at the L4–5 level. B: Postoperative axial T2-weighted MR image at the same level showing an effective decompression.

Measurements of Clinical and Radiological Outcomes

At each visit, the patients were asked to complete the outcome questionnaire and plain radiographs were obtained. The clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry Disability Index (ODI), and 36-Item Short Form Survey (SF-36) outcome questionnaire; assessments were performed preoperatively and at 1, 3, 6, 12, and 24 months postoperatively. The radiological parameters were measured preoperatively and at 1 and 2 years postoperatively in all patients. The radiological features measured were lumbar lordosis (LL), disc-wedging angle, percentage of slippage, and disc height index (DHI) measured on plain standing radiographs. LL was determined by measuring the Cobb angle formed by the lines between the superior margin of the L-1 vertebra and the inferior margin of the L-5 vertebra, as assessed on lateral plain radiographs. The disc-wedging angle was determined by measuring the Cobb angle formed by the lines between the inferior margin of the upper vertebra and the superior margin of the lower vertebra at the affected level, as assessed on anteroposterior plain radiographs. The slip percentage, which is the degree of slippage in relation to the anteroposterior diameter of the superior margin of the lower vertebra, was calculated using the Taillard method.12 DHI, which is the ratio between the mean value of the disc height (measured in 3 points at each operated level) and the mean sagittal diameter of the consecutive vertebra, was calculated at the mid–vertebral level using the modified Inoue method (Fig. 4).7 Radiological progression was defined as a disc-wedging progression of 3° or more, a slip percentage progression of 5% or more, or a disc height (5% or more DHI) progression of 2 mm or more.15 The percentage of facet joint preservation was calculated using the following equation and parameters assessed on preoperative and postoperative CT scans: (length of the postoperative facet joint/length of the preoperative facet joint) × 100 (Fig. 5). The outcomes of EPD were compared between the two groups. All measurements were performed twice, independently by 3 spine surgeons, with an interval of 2 weeks between the measurements in order to decrease the incidence of intraobserver (Pearson’s correlation coefficient = 0.915, range 0.880–0.941) and interobserver (Pearson’s correlation coefficient = 0.905, range 0.863–0.928) errors.

Fig. 4.
Fig. 4.

Radiological measurement of the DHI at the affected level. A and B: Sagittal diameter measured from the midvertebral level of the consecutive vertebra (white line). Line 1 (black line): the line between the anterosuperior corner of the upper vertebra and the anteroinferior corner of the lower vertebra. Line 2 (black line): the line between the middle-superior point of the upper vertebra and the middle-inferior point of the lower vertebra. Line 3 (black line): the line between the posterosuperior corner of the upper vertebra and the posteroinferior corner of the lower vertebra. a, b, and c: Measured disc height on lines 1, 2, and 3, respectively. DHI, measured by the modified Inoue method, was calculated using the following formula: DHI (%) = {[(a + b + c)/3]/[(A + B)/2]} × 100.

Fig. 5.
Fig. 5.

The percentage of facet joint preservation measured on axial CT scans preoperatively (A) and postoperatively (B). Percentage of facet joint preservation = (b/a) × 100.

Statistical analysis was performed using SPSS software version 21 for Windows (IBM Corp.). Data are expressed as mean ± SD. Clinical and radiological outcomes were compared using ANOVA. The post hoc test was used to analyze individual differences. A Student t-test was also performed to determine the differences between two groups; p < 0.05 was considered statistically significant.

Results

The mean baseline preoperative VAS, ODI, and SF-36 scores were 76.0 ± 8.1, 46.7 ± 7.6, and 32.5 ± 2.8, respectively. The mean VAS, ODI, and SF-36 scores showed significant improvements at 1 month postoperatively: 30.8 ± 16.1, 27.3 ± 10.8, and 46.6 ± 7.2, respectively. Similar VAS, ODI, and SF-36 results were found at the 2-year follow-up (23.8 ± 12.7, 23.0 ± 10.5, and 48.5 ± 5.7, respectively) (Table 1). Furthermore, we compared the clinical outcomes between the two groups and found no statistically significant differences in VAS, ODI, and SF-36 scores between the groups (Table 2).

TABLE 1.

Mean values of clinical parameters in the preoperative and follow-up periods

ParameterPreop1 Mo3 Mos6 Mos12 Mos24 Mosp Value
 VAS76.030.825.722.023.223.8<0.001
 ODI46.727.324.722.823.523.0<0.001
 SF-3632.546.648.048.448.148.5<0.001

VAS scores were calculated with the sum of 100 points.

TABLE 2.

Comparison of clinical outcomes between the two groups

Outcome MeasureGroup 1 (n = 27)Group 2 (n = 23)p Value
VAS score
 At enrollment76.5 (8.0)75.4 (8.4)0.813
 1 mo postop31.2 (12.3)30.4 (13.2)0.994
 3 mos postop26.1 (13.6)25.2 (12.6)0.862
 6 mos postop22.5 (13.6)21.5 (12.7)0.604
 12 mos postop23.6 (13.6)22.7 (11.2)0.866
 24 mos postop24.1 (12.1)23.5 (12.3)0.535
ODI score
 At enrollment47.3 (2.7)46.1 (2.2)0.861
 1 mo postop27.5 (5.8)27.0 (5.6)0.487
 3 mos postop24.5 (3.2)24.9 (4.1)0.658
 6 mos postop22.1 (4.1)23.3 (3.2)0.269
 12 mos postop23.1 (4.8)23.9 (3.3)0.875
 24 mos postop22.5 (3.1)23.6 (2.3)0.181
SF-36 score
 At enrollment32.1 (4.8)32.9 (5.1)0.833
 1 mo postop46.3 (5.7)47.0 (5.9)0.824
 3 mos postop47.8 (5.1)48.3 (4.6)0.942
 6 mos postop48.6 (4.5)48.2 (4.6)0.546
 12 mos postop48.2 (4.1)47.9 (3.8)0.770
 24 mos postop48.7 (4.0)48.3 (3.70)0.753

Values are presented as mean (SD).

Group 1 had no accompanying spondylolisthesis, whereas group 2 did have accompanying spondylolisthesis.

Of radiological parameters measured preoperatively and at 1 and 2 years postoperatively (Table 3), no significant changes were found between preoperative parameters and postoperative 1- and 2-year values for LL, disc-wedging angle, slip percentage, and DHI. In addition, no statistically significant differences were noted between the groups regarding these parameters (Table 4). Radiological progression was observed in 2 patients (4%) from group 2 at 2 years postoperatively. The slippage percentage increased from 8.4% preoperatively to 15.9% at the 2-year follow-up.

TABLE 3.

Mean value of radiological parameters in the preoperative and follow-up periods

ParameterPreop1 Yr Postop2 Yrs Postopp Value
LL (°)26.128.928.80.795
Disc-wedging angle (°)1.61.81.90.418
Slippage percentage (%)3.74.75.10.721
DHI (%)25.324.323.70.887
TABLE 4.

Comparison of radiological outcomes between the two groups

Outcome ParameterGroup 1 (n = 27)Group 2 (n = 23)p Value
LL (°)
 At enrollment27.3 (8.2)24.7 (6.0)0.186
 12 mos postop30.1 (8.3)27.4 (5.9)0.188
 24 mos postop29.3 (8.6)28.3 (7.1)0.660
Disc-wedging angle (°)
 At enrollment1.7 (1.8)1.4 (1.5)0.623
 12 mos postop1.9 (1.8)1.7 (1.6)0.643
 24 mos postop2.0 (2.1)1.8 (2.0)0.677
Slippage percentage (%)
 At enrollment3.8 (4.7)3.5 (4.1)0.794
 12 mos postop4.8 (4.8)4.5 (4.5)0.860
 24 mos postop5.2 (5.3)5.0 (4.7)0.880
Disc height index (%)
 At enrollment25.6 (4.1)25.0 (4.8)0.763
 12 mos postop24.6 (5.1)23.9 (3.9)0.533
 24 mos postop23.9 (4.7)23.5 (3.6)0.820

Values are presented as the mean (SD).

There were no significant differences in terms of operative time, quantity of drainage, and percentage of facet joint preservation between the groups postoperatively (Table 5).

TABLE 5.

Comparison of operative time, volume of drainage, and percentage facet joint preserved between the two groups

VariableGroup 1 (n = 27)Group 2 (n = 23)p Value
Operative time (mins)72.6 (16.3)76.1 (14.3)0.430
Drainage (ml)11.3 (12.6)10.8 (13.3)0.897
Percentage of facet joint (%)
 Ipsilateral83.9 (6.6)84.4 (5.7)0.752
 Contralateral90.9 (7.6)91.0 (8.1)0.965

Values are presented as mean (SD).

Intraoperative dural tear injuries occurred in 2 cases, but the patients did not report any specific symptoms. These dural injuries were covered with sealant matrix (TachoSil, Baxter) introduced through the endoscopic working channel and the irrigation was stopped. No other serious complications occurred during the study.

Discussion

Although open laminectomy has been shown to be an effective procedure for LSS decompression, the classic procedure can lead to postoperative lumbar instability.3 Furthermore, laminectomy in the presence of preexisting spondylolisthesis is associated with a high rate of poor clinical outcomes, such as postoperative segmental instability and the need for reoperation. Iguchi et al. reported the development of new spondylolisthesis after decompressive laminectomy in 6% of patients without preoperative slippage at the 10-year follow-up, and the average progression of slippage was 2.3 mm.6 Epstein reported that progression from grade 1 to grade 2 spondylolisthesis at the 2-year follow-up was found in 31.4% of cases.5 Blumenthal et al. reported that the reoperation rate with fusion was 37.5% at 3-year follow-up.2

Minimally invasive surgery using a microscope or endoscope has been widely performed for the treatment of LSS. Several studies have reported that preoperative spondylolisthesis does not worsen the outcome of minimally invasive surgery in selected patients with mild spondylolisthesis. Chang et al. compared the outcomes of unilateral laminotomy with bilateral decompression in 165 patients with LSS who were divided into two groups according to the presence or absence of preoperative spondylolisthesis.4 They reported that favorable outcomes were maintained for up to 5 years and that the progression of slippage was uncommon (8%) in both groups. Alimi et al. reported that 3.5% of patients underwent reoperation requiring same-level fusion among 110 patients who underwent minimally invasive laminectomy in which tubular retractors were used.1 They reported no significant differences in clinical outcomes or reoperation rate in patients with and without preoperative spondylolisthesis, and no significant slippage progression was found after surgery.

EPD can spare the attachments of the paraspinal ligaments, muscles, and dorsal branches of the spinal nerves, which stabilize the spine. Therefore, it can help the postoperative strengthening of the back muscles and maintain the stabilization of the motion segment. In a report by Komp et al. that investigated 135 patients treated with endoscopic or microscopic decompression and who were followed up for 2 years, almost complete improvements were obtained in 72% of the patients based on the outcome scores.8 However, they reported that the number of patients who reported increasing back pain during the follow-up period was higher in the microscopic surgery group and that the incidence of postoperative pain and pain medication use were significantly reduced in the endoscopic surgery group. In 71 patients who underwent endoscopic decompression, they reported a statistically significant improvement in ODI and VAS scores from 84 and 85, respectively, preoperatively, to 28 and 17, respectively, at 2 years. Several reports that studied the results of endoscopic decompression surgery showed favorable outcomes with low reoperation rates (3%–9.5%) and a minimal progression of the preoperative spondylolisthesis.8,9,13 In the present study, the mean VAS, ODI, and SF-36 scores at 1 month postoperatively were significantly improved from those obtained at baseline, and these improvements were maintained at the 2-year follow-up visits. No significant changes were found in the values of LL, disc-wedging angle, and slip percentage at 1 and 2 years postoperatively compared to the preoperative values. Therefore, we consider that preoperative spondylolisthesis does not worsen the clinical and radiological outcomes in selected patients presenting with mild spondylolisthesis who undergo EPD. However, because follow-up in the present study was only 2 years, the long-term outcomes after the EPD remain unclear. Among 57 patients who underwent EPD, 3 patients needed revision surgery: 2 underwent revision fusion surgery and 1 underwent microscopic decompression surgery for the presence of a postoperative epidural hematoma. The low radiological progression (4%) and revision fusion surgery (3.5%) rates found in our study are consistent with the experiences of other authors. In the present study, the mean percentage of facet joint preservation was 84% on the ipsilateral (approach) side and 91% on the contralateral side, being significantly lower on the ipsilateral side. Because decompression can be performed more easily and efficiently on the approach side than on the contralateral side, we consider that the procedure should be performed on the side of the main pathology. However, the percentage of facet preservation has no statistical correlation with clinical outcomes.

Recently, several studies reported the results of endoscopic decompression surgery for the treatment of LSS under general anesthesia.8,9,13 We performed EPD under local anesthesia with conscious sedation for the treatment of LSS. Dexmedetomidine was intravenously administered during EPD, and this infusion was titrated to keep the patient under light to moderate sedation. This sedation protocol was sufficient for the control of pain that resulted from bony decompression. EPD performed under local anesthesia has some advantages. First, it provides the surgeon with feedback regarding any contact or tension with neural structures, as the patient will respond to this painful stimulus. Second, this method reduces the morbidity that is attendant on the induction of general anesthesia, especially in older patients. Finally, the surgeon can quickly evaluate the motor response during the procedure in case of an unclear situation.

This study had several limitations. First, the number of tested subjects was relatively small and no control group was used, diminishing the statistical power of the study. Second, because of the relatively short follow-up period, further studies with a larger number of patients and longer-term outcomes are necessary. Finally, 7 patients were excluded from the present study because of incomplete follow-up data. Therefore, we could not ascertain their exact clinical and radiological outcomes.

Conclusions

EPD performed under local anesthesia is an effective procedure for treating LSS, with favorable outcomes. Similar results can be obtained using this procedure in patients with and without preoperative spondylolisthesis. Moreover, it has the potential benefits of minimally invasive surgery such as lower blood loss, more rapid rehabilitation, lower postoperative back pain intensity, and lower anesthesia-related morbidity rates. Preexistent spondylolisthesis does not worsen the clinical and radiological outcomes of EPD in selected patients with mild spondylolisthesis.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Lee, Youn. Acquisition of data: Goh. Analysis and interpretation of data: Shin, Goh. Drafting the article: Shin, Son. Critically revising the article: Son. Reviewed submitted version of manuscript: Lee. Approved the final version of the manuscript on behalf of all authors: Lee. Statistical analysis: Goh. Study supervision: Lee.

References

  • 1

    Alimi MHofstetter CPPyo SYPaulo DHärtl R: Minimally invasive laminectomy for lumbar spinal stenosis in patients with and without preoperative spondylolisthesis: clinical outcome and reoperation rates. J Neurosurg Spine 22:3393522015

  • 2

    Blumenthal CCurran JBenzel ECPotter RMagge SNHarrington JF Jr: Radiographic predictors of delayed instability following decompression without fusion for degenerative grade I lumbar spondylolisthesis. J Neurosurg Spine 18:3403462013

  • 3

    Bresnahan LOgden ATNatarajan RNFessler RG: A biomechanical evaluation of graded posterior element removal for treatment of lumbar stenosis: comparison of a minimally invasive approach with two standard laminectomy techniques. Spine (Phila Pa 1976) 34:17232009

  • 4

    Chang HSFujisawa NTsuchiya TOya SMatsui T: Degenerative spondylolisthesis does not affect the outcome of unilateral laminotomy with bilateral decompression in patients with lumbar stenosis. Spine (Phila Pa 1976) 39:4004082014

  • 5

    Epstein NE: Lumbar laminectomy for the resection of synovial cysts and coexisting lumbar spinal stenosis or degenerative spondylolisthesis: an outcome study. Spine (Phila Pa 1976) 29:104910562004

  • 6

    Iguchi TKurihara ANakayama JSato KKurosaka MYamasaki K: Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine (Phila Pa 1976) 25:175417592000

  • 7

    Inoue HOhmori KMiyasaka KHosoe H: Radiographic evaluation of the lumbosacral disc height. Skeletal Radiol 28:6386431999

  • 8

    Komp MHahn POezdemir SGiannakopoulos AHeikenfeld RKasch R: Bilateral spinal decompression of lumbar central stenosis with the full-endoscopic interlaminar versus microsurgical laminotomy technique: a prospective, randomized, controlled study. Pain Physician 18:61702015

  • 9

    Ruetten SKomp MMerk HGodolias 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 10:4764852009

  • 10

    Slätis PMalmivaara AHeliövaara MSainio PHerno AKankare J: Long-term results of surgery for lumbar spinal stenosis: a randomised controlled trial. Eur Spine J 20:117411812011

  • 11

    Soliman HM: Irrigation endoscopic decompressive laminotomy. A new endoscopic approach for spinal stenosis decompression. Spine J 15:228222892015

  • 12

    Taillard W: [Spondylolisthesis in children and adolescents.] Acta Orthop Scand 24:1151441954 (Fr)

  • 13

    Torudom YDilokhuttakarn T: Two portal percutaneous endoscopic decompression for lumbar spinal stenosis: preliminary study. Asian Spine J 10:3353422016

  • 14

    Wilby MJSeeley HLaing RJ: Laminectomy for lumbar canal stenosis: a safe and effective treatment. Br J Neurosurg 20:3913952006

  • 15

    Yamada KMatsuda HCho HHabunaga HKono HNakamura H: Clinical and radiological outcomes of microscopic partial pediculectomy for degenerative lumbar foraminal stenosis. Spine (Phila Pa 1976) 38:E723E7312013

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Article Information

Correspondence Jung Sub Lee: Pusan National University School of Medicine, Busan, Korea. jungsublee@pusan.ac.kr.

INCLUDE WHEN CITING Published online September 28, 2018; DOI: 10.3171/2018.5.SPINE171337.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Flowchart of patient enrollment in the study.

  • View in gallery

    An illustration of the surgical decompression technique. Copyright Jung Sub Lee. Published with permission.

  • View in gallery

    A: Preoperative axial T2-weighted MR image of the lumbar spine at the L4–5 level. B: Postoperative axial T2-weighted MR image at the same level showing an effective decompression.

  • View in gallery

    Radiological measurement of the DHI at the affected level. A and B: Sagittal diameter measured from the midvertebral level of the consecutive vertebra (white line). Line 1 (black line): the line between the anterosuperior corner of the upper vertebra and the anteroinferior corner of the lower vertebra. Line 2 (black line): the line between the middle-superior point of the upper vertebra and the middle-inferior point of the lower vertebra. Line 3 (black line): the line between the posterosuperior corner of the upper vertebra and the posteroinferior corner of the lower vertebra. a, b, and c: Measured disc height on lines 1, 2, and 3, respectively. DHI, measured by the modified Inoue method, was calculated using the following formula: DHI (%) = {[(a + b + c)/3]/[(A + B)/2]} × 100.

  • View in gallery

    The percentage of facet joint preservation measured on axial CT scans preoperatively (A) and postoperatively (B). Percentage of facet joint preservation = (b/a) × 100.

References

1

Alimi MHofstetter CPPyo SYPaulo DHärtl R: Minimally invasive laminectomy for lumbar spinal stenosis in patients with and without preoperative spondylolisthesis: clinical outcome and reoperation rates. J Neurosurg Spine 22:3393522015

2

Blumenthal CCurran JBenzel ECPotter RMagge SNHarrington JF Jr: Radiographic predictors of delayed instability following decompression without fusion for degenerative grade I lumbar spondylolisthesis. J Neurosurg Spine 18:3403462013

3

Bresnahan LOgden ATNatarajan RNFessler RG: A biomechanical evaluation of graded posterior element removal for treatment of lumbar stenosis: comparison of a minimally invasive approach with two standard laminectomy techniques. Spine (Phila Pa 1976) 34:17232009

4

Chang HSFujisawa NTsuchiya TOya SMatsui T: Degenerative spondylolisthesis does not affect the outcome of unilateral laminotomy with bilateral decompression in patients with lumbar stenosis. Spine (Phila Pa 1976) 39:4004082014

5

Epstein NE: Lumbar laminectomy for the resection of synovial cysts and coexisting lumbar spinal stenosis or degenerative spondylolisthesis: an outcome study. Spine (Phila Pa 1976) 29:104910562004

6

Iguchi TKurihara ANakayama JSato KKurosaka MYamasaki K: Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine (Phila Pa 1976) 25:175417592000

7

Inoue HOhmori KMiyasaka KHosoe H: Radiographic evaluation of the lumbosacral disc height. Skeletal Radiol 28:6386431999

8

Komp MHahn POezdemir SGiannakopoulos AHeikenfeld RKasch R: Bilateral spinal decompression of lumbar central stenosis with the full-endoscopic interlaminar versus microsurgical laminotomy technique: a prospective, randomized, controlled study. Pain Physician 18:61702015

9

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