Increasing knowledge of the pathoanatomy, coupled with high-resolution imaging, has allowed a precise localization of nerve compression, which usually occurs at the level of the intervertebral space and the bulging yellow ligaments.78,87,93 Various authors have proposed more tailored and less invasive techniques in the treatment of acquired lumbar stenosis.11,54,66 In particular, bilateral 4,50,57,78,91,93 and unilateral laminotomy for bilateral decompression31,49,55,59,60,73,74,87 have been described. The reported results have been encouraging, with success rates as high as 90%, but most of these clinical series included small patient populations, recruited an inhomogeneous population, were retrospective, or lacked a control group. In the few comparative studies investigators did not find a significant benefit associated with a less invasive technique compared with laminectomy15,49,61,76 but reported a higher incidence of perioperative (neurological) complications. As a result, the authors of review articles concluded that laminotomies should be reserved for cases in which the disease was far less severe or for specific subgroups of patients.7,24,70,77 Comparative data obtained in a population of sufficient size, however, have not been reported in a prospective trial.7
The purpose of our prospective study was to compare the safety and the clinical outcomes after unilateral laminotomy, bilateral laminotomy, and laminectomy in patients with lumbar spinal stenosis who were randomized to one of the three treatment groups.
The study protocol was approved by the institutional ethics committee. One hundred twenty patients (mean age 68 ± 9 years, range 44–86 years) with lumbar spinal stenosis refractory to adequate conservative treatment were recruited consecutively during a 30-month period. The following inclusion criteria were used: 1) symptoms of neurogenic claudication or radiculopathy; 2) radiological/neuroimaging evidence of degenerative lumbar stenosis; 3) absence of associated pathological entities such as disc herniations or instability; and 4) no history of surgery for lumbar stenosis or lumbar fusion.
Symptoms were considered refractory to nonsurgical management if conservative measures, particularly nonsteroidal antiinflammatory drug and physical therapies, had been administered for at least 3 months without sufficient improvement. In contrast to previous studies in which the authors allowed discectomy to be part of the decompression11,49,57,61,66 or included fusion procedures,5,20,61 we attempted to study a more homogeneous patient population. Therefore, we excluded from outcome analysis three patients who required discectomies due to significant intraoperatively noted discogenic nerve compression, which had not been identified on preoperative imaging studies. Thus the study population was reduced to 117 individuals in whom follow-up data were obtained and evaluated. Spinal instability was defined as sagittal-plane translation of 5 mm or more documented on flexion—extension radiography.23,89 Patients presenting with stable spondylolisthesis or a history of surgery for herniated lumbar discs were not excluded.
All patients underwent a standardized neurological and clinical assessment to evaluate walking distance, and pain was measured separately for the low back and the legs according to a self-assessment 10-point VAS.68 Disability was assessed using the RMS (score range 0–24), which has been validated64 and reported on for German-language speakers.90 Physical and mental health status was measured using the SF-36 health survey.85 Possible depressive symptoms, known to influence outcome following spinal surgery, were assessed using a self-assessment depression scale (the ADS [score range 0–60]).36
Radiological/neuroimaging workup included MR imaging, myelography, and postmyelography CT scanning for identification of the involved segments. In the majority (73) of patients we observed multisegmental stenosis, which required decompression of 207 levels overall (mean 1.7 ± 0.7 per patient). The L3–4 and the L4–5 levels were most commonly involved (in 83 [40.1%] and 95 [45.9%] of cases, respectively).
Each patient's admission number was used to blind the randomization to personal data. If a patient met the inclusion criteria according to the admitting physician and informed consent was obtained, a concealed computer-generated randomization list was used to assign the patient to one of the treatment groups: bilateral laminotomy (Group 1), unilateral laminotomy (Group 2), and laminectomy (Group 3).
All patients underwent surgery after induction of general endotracheal anesthesia while in the prone position. An operating microscope (Carl Zeiss Co., Oberkochen, Germany) was used in all cases. Surgery was performed in a standardized manner. The surgical approach is represented by three-dimensional and axial postoperative CT scans in Fig. 1. All three techniques used in the groups had been routinely performed at our institution in the 2 years preceding the study.
4,50,57,78,91,93 The bone from the inferior aspect of the cranial lamina and, to a minimal degree, from the superior aspect of the subjacent lamina was resected, and subsequent flavectomy was performed to expose the spinal canal. The medial aspect of the facet joint was resected to decompress the lateral recess. The spinous process, the supra- and interspinous ligaments, and a substantial portion of the lamina were preserved.
31,49,55,59,60,73,74,87 Following an ipsilateral laminotomy as described earlier, the spinous process was undercut with a high-speed burr. By angling the microscopic view following ipsilateral decompression, the contralateral ligamentum flavum and the medial aspects of the contralateral facet joints were resected for contralateral decompression.
The spinous process and the laminae of the involved segment(s) as well as the medial aspects of the facet joints were resected (facet-sparing laminectomy).16 A hemifacetectomy was never performed.
High-speed burrs and Kerrison rongeurs were used in all procedures. Special care was taken in all three groups to minimize facet joint resection by using an undercutting technique. The laminotomy approaches were performed through speculum-type retractors. Suction drains were not routinely placed. Ambulation was encouraged on the day of surgery. Postoperative CT scans were acquired in all patients before discharge to evaluate the adequacy of the decompression.
Intraoperative parameters such as the length of skin incision, duration of the procedure, EBL, and intraoperative complications (for instance, incidental durotomy) were documented on a standardized form in the operating room. For comparison, these data were analyzed in relation to the number of decompressed levels. Perioperative morbidity also included reoperations within 30 days and the presence of an increased postoperative radicular deficit such as a neural injury. The technical difficulty of the procedure was subjectively rated by the surgeon on a 10-point scale.
Standardized self-assessment questionnaires were used at follow-up examinations 3, 6, and a minimum of 12 months after surgery. Pain (VAS score), walking distance, RMS scores, and subjective overall success rate (0% no success; 100% complete success) were recorded. The SF-36 was used for assessment at the 12-month follow-up examination. To evaluate outcome of low-back pain and leg pain separately and to differentiate between resting conditions and walking, improvement of these parameters was analyzed on a self-assessment five-point scale (much improved, somewhat improved, unchanged, somewhat worse, and much worse). To evaluate patient satisfaction with the postoperative result, the PSI (a modified subitem of the NASS outcome questionnaire) was administered.14 Additionally, the questionnaire included items asking whether the patients were satisfied with postoperative pain reduction and the improvement in ability to perform everyday activities.
Patients presenting with significant residual or recurrent symptoms underwent postoperative MR imaging and flexion—extension radiography. In cases of instability, residual or adjacent-level stenosis, or lumbar facet syndrome, surgical intervention was performed and documented.
All values are expressed as the means ± SDs. The unpaired Student t-test, Mann—Whitney rank-sum test, chisquare test, and Fisher exact test were used as applicable to analyze differences in the preoperative clinical and demographic characteristics (age, sex ratio, duration of symptoms, clinical presentation, VAS, RMS, and SF-36), in the intraoperative variables; and in clinical outcome variables between groups (VAS, RMS, SF-36, and PSI scores as well as reoperations). For analysis of overall complication rates, a patient's course was defined as complicated if at least one complication was present perioperatively. The paired Student t-test and Wilcoxon signed-rank test were used to analyze changes over time within each group. Statistical significance was set at a probability value less than 0.05.
Forty patients each were randomized to one of the three groups. Based on the VAS preoperative overall pain was 7.5 ± 2.3. The patients suffered from neurogenic claudication for a mean of 20.2 ± 29.7 months, and walking distance was reduced to 250 ± 370 m. The overall RMS disability score was 17 ± 4.3. There were no intergroup significant differences in the preoperative characteristics (Table 1). Cases of severe stenosis were evenly distributed among groups.
| Group | |||
|---|---|---|---|
| Parameters | 1 | 2 | 3 |
| no. of cases | 40 | 40 | 40 |
| mean age (yrs) | 70 ± 7 | 67 ±6 | 69 ± 10 |
| male/female | 20:20 | 15:25 | 18:22 |
| mean body mass index (kg/m2) | 28 ± 4 | 29 ± 6 | 29 ± 4 |
| level (no. of cases) | |||
| L1–2 | 0 | 0 | 2 |
| L2–3 | 6 | 11 | 7 |
| L3–4 | 26 | 28 | 29 |
| L4–5 | 30 | 31 | 34 |
| L5—S1 | 1 | 1 | 1 |
| symptom (no. of cases) | |||
| LBP | 35 | 36 | 37 |
| leg pain | 34 | 37 | 36 |
| neurogenic claudication | 38 | 40 | 39 |
| subjective numbness | 33 | 28 | 29 |
| subjective weakness | 29 | 32 | 29 |
| mean duration of symptoms (mos) | |||
| LBP | 68 ± 71 | 65 ± 82 | 62 ± 73 |
| leg pain | 26 ± 43 | 20 ± 25 | 23 ± 30 |
| claudication | 22 ± 40 | 15 ± 18 | 23 ± 28 |
| walking aids (no. of cases) | |||
| none | 20 | 26 | 23 |
| cane | 9 | 97 | |
| crutches | 2 | 44 | |
| walker/wheelchair | 9 | 4 | 3 |
| mean ADS score (range 0–60) | 22 ± 10 | 21 ± 10 | 20 ± 10 |
* Mean values are presented as the means ± SDs. Abbreviation: LBP = low-back pain.
Spinal canal decompression was adequately achieved in all cases according to the surgeon. Therefore, the scheduled procedure was adhered to in all patients. The duration of surgery was prolonged significantly in Group 1. The EBL was lowest in patients who underwent the unilateral approach in Group 2. No patient required a blood transfusion. The skin incision was significantly longer in Group 3 patients compared with those who underwent laminotomy. The technical difficulty of the procedures was rated highest in Group 2 (Table 2).
| Parameters | 1 | 2 | 3 |
|---|---|---|---|
| duration of op (mins/level) | 90 ± 31 | 77 ± 28† | 73 ± 32* |
| EBL (ml/level) | 212 ± 147 | 177 ± 99‡ | 227 ± 154 |
| length of skin incision (cm/level) | 3.6 ± 0.8 | 3.2 ± 0.7†‖ | 4.7 ± 1.4§ |
| difficulty of op (range 0–10) | 6.0 ± 1.5 | 7.3 ± 1.5§‖ | 5.9 ± 1.6 |
* p < 0.01 compared with Group 1.
† p < 0.05 compared with Group 1.
‡ p < 0.05 compared with Group 3.
§ p < 0.001 compared with Group 1.
‖ p < 0.001 compared with Group 3.
There were no perioperative deaths. Of all surgically treated levels unintended durotomy occurred in 3.2% (Group 1, two levels), 7% (Group 2, five levels), and 11% (Group 3, eight levels). Dural tears were not noticeably associated with postoperative morbidity, but they were with increased duration of surgery and increased EBL (data not shown). In most cases direct suturing was performed using special microinstruments. In difficult sites, such as contralaterally in the unilateral approach, Gelfoam and/or fibrin glue were applied. No subsequent postoperative CSF fistula was observed.
An epidural hematoma requiring reoperation was documented on MR imaging in in two Group 2 patients, and two Group 3 patients who presented with postoperative urinary retention (two cases; both in Group 3), increased pain (one case; Group 2), or progressive radicular deficit (one case; Group 2). Overall, there were two patients in Group 2 who suffered deterioration of L-5 radiculopathy postoperatively, one case of which was minor and the patient recovered prior to discharge. One wound infection was noted in a laminectomy-treated patient after evacuation of an epidural hematoma requiring a second reoperation and antibiotic therapy (Table 3).
| Group (%) | |||
|---|---|---|---|
| Complications | 1 | 2 | 3 |
| incidental durotomy | 2 (5.0) | 5 (12.5) | 8 (20.0) |
| increased radicular deficit | 0 (0.0) | 2 (5.0) | 0 (0.0) |
| reop | 0 (0.0) | 2 (5.0) | 2 (5.0) |
| epidural hematoma | 0 | 2 | 2 |
| wound infection | 0 | 0 | 1 |
| total | 2 (5.0) | 7 (17.5) | 9 (22.5)† |
* Complications were counted per patient—that is, the number of complicated cases per group was assessed regardless of whether one patient suffered from a single or multiple complications. Therefore, the total complication rates do not represent an arithmetic summation of detailed complication rates.
† p < 0.05 compared with Group 1.
No patient in Group 1, three patients in Group 2 and two patients in Group 3 experienced symptomatic complications (NS). Overall, the perioperative morbidity rate, including the clinically occult incidental durotomies, was lower in Group 1 (5.0%) than in Group 3 (22.5%; p < 0.05 compared with Group 1) or Group 2 (17.5%).
Follow-up data for outcome analysis were collected at 3, 6, and a minimum of 12 months after surgery. In most patients final assessment was conducted 12 to 18 months postoperatively (mean follow-up period 15.5 months). In that time period four patients died of unrelated causes. Two patients refused to participate in the study and one patient was lost to follow up. Thus, follow-up status of at least 1 year was determined in 110 patients (94% of the cohort and 97% of survivors; Table 4). In six patients, the latter part of the questionnaire (specific to the RMS and SF-36) was insufficiently completed, precluding analysis.
| Group (%) | ||||
|---|---|---|---|---|
| Assessment Period | 1 | 2 | 3 | Total No. |
| preop | ||||
| randomized† | 40 | 40 | 40 | 120 |
| included in outcome | 39 | 40 | 38 | 117 |
| analysis† | ||||
| 3 mos postop | ||||
| alive | 38 | 40 | 37 | 115 |
| FU (%) | 37 (97.4) | 39 (97.5) | 34 (91.9) | 110 (95.7) |
| 6 mos postop | ||||
| alive | 38 | 40 | 37 | 115 |
| FU (%) | 38 (100) | 40 (100) | 35 (94.6) | 113 (98.3) |
| 12 mos postop | ||||
| alive | 38 | 39 | 36 | 113 |
| FU (%) | 37 (97.4) | 39 (100) | 34 (94.4) | 110 (97.3) |
* FU = follow up.
† One hundred twenty patients were initially randomized, three of whom were excluded from outcome analysis because of significant disc protrusion requiring additional discectomy.
Surgical decompression resulted in a dramatic reduction of overall pain in all three groups (p < 0.001). Compared with that observed in Group 1, however, significantly more residual pain (Fig. 2) was documented in Groups 2 and 3–3.6 ± 2.7 (Group 2) and 4 ± 1 (Group 3) compared with 2.3 ± 2.4 (Group 1) at the 12-month follow-up evaluation (p < 0.05). Differentiating between low-back pain and leg pain during resting conditions and walking revealed that superior pain relief occurred in Group 1 patients, particularly during walking and especially in the legs (Fig. 3). The most prominent symptom of lumbar stenosis, neurogenic claudication (that is, leg pain during walking) improved in 92% of patients in Group 1 compared with 74 and 68% in Groups 2 and 3 (p < 0.05), respectively.
Walking distance varied greatly among individual patients, but overall ambulation recovered rapidly after decompression and remained stable during the follow-up period (Fig. 4 left). There was no significant difference among groups (3663 ± 3247, 2958 ± 3561, and 2318 ± 3509 m, compared with preoperative distances at 12 months in Groups 1, 2, and 3, respectively; NS among groups; p < 0.001) compared with preoperative distance. The same was true for the RMS scores, which reached 8.1 ± 7 (Group 1), 10.9 ± 7.5 (Group 2), and 8.5 ± 7.3 (Group 3) (NS among groups; p < 0.001 compared with preoperative scores; Fig. 4 center).
Comparison of pre- and postoperative SF-36 scores demonstrated a marked and significant improvement, particularly of the physical component but also of most mental subscales, in all three groups. Again, scores were highest in Group 1 patients, with the most pronounced and significant benefit in the bodily pain subscale compared with Groups 2 and 3 (Table 5).
| Group | |||
|---|---|---|---|
| Subscale | 1 | 2 | 3 |
| physical functioning | |||
| admission | 17.8 ± 19.0 | 27.7 ± 27.4 | 22.8 ± 21.1 |
| FU | 63.6 ± 26.2† | 42.6 ± 31.8‡§ | 51.4 ± 30.8‡ |
| role-physical functioning | |||
| admission | 6.3 ± 19.3 | 9.6 ± 26.8 | 16.4 ± 29.0 |
| FU | 53.2 ± 45.5† | 39.8 ± 44.0‡ | 52.9 ± 38.9‡ |
| bodily pain | |||
| admission | 16.9 ± 17.7 | 16.7 ± 14.7 | 18.1 ± 18.2 |
| FU | 61.0 ± 25.3† | 46.6 ± 29.6†‖ | 44.9 ± 34.3†‖ |
| general health perception | |||
| admission | 45.6 ± 14.9 | 46.1 ± 15.6 | 43.4 ± 18.8 |
| FU | 56.5 ± 17.8** | 47.0 ± 25.4‖ | 52.9 ± 20.6 |
| vitality | |||
| admission | 32.0 ± 15.1 | 32.3 ± 19.6 | 31.8 ± 17.3 |
| FU | 53.7 ± 19.8† | 45.4 ± 27.0†‖ | 50.2 ± 26.1† |
| social functioning | |||
| admission | 55.2 ± 30.4 | 40.8 ± 28.3 | 51.8 ± 30.0 |
| FU | 80.2 ± 24.1† | 65.3 ± 30.3**‖ | 76.9 ± 32.2‡ |
| role-emotional functioning | |||
| admission | 49.1 ± 45.4 | 50.0 ± 48.0 | 44.8 ± 43.5 |
| FU | 72.0 ± 43.1** | 51.9 ± 45.6 | 71.8 ± 40.8** |
| mental health index | |||
| admission | 47.4 ± 17.4 | 50.9 ± 20.7 | 46.4 ± 21.3 |
| FU | 71.4 ± 18.3† | 64.2 ± 24.3‡ | 69.4 ± 22.2† |
| physical component summary | |||
| admission | 23.7 ± 7.5 | 25.4 ± 7.3 | 25.8 ± 5.2 |
| FU | 40.2 ± 10.6† | 33.9 ± 13.3†‖ | 35.5 ± 12.6** |
| mental component summary | |||
| admission | 43.8 ± 10.7 | 42.2 ± 13.0 | 41.2 ± 11.9 |
| FU | 50.5 ± 10.3‡ | 46.1 ± 12.6 | 51.0 ± 12.9† |
* Low values represent worse health status; normal values differ with age of the patient population.
† p < 0.001 compared with admission.
‡ p < 0.01 compared with admission.
§ p < 0.01 compared with Group 1.
‖ p < 0.05 compared with Group 1.
** p < 0.05 compared with admission.
Overall PSI scores were significantly superior after bilateral laminotomy. Overall 2.7% (one of 37; [Group 1]), 25.6% (10 of 39; [Group 2]), and 26.5% (nine of 34; [Group 3]) of patients were unsatisfied after 12 months (p < 0.01) (Table 6). This difference remained stable within the 1st postoperative year and is also reflected by a self-reported success rate of approximately 80% in Group 1 compared with approximately 65% in Groups 2 and 3 (Fig. 4 right). In general, patients were more satisfied with the reduced pain levels than with the improvement in everyday activities (Table 6).
| Group (%) | |||
|---|---|---|---|
| FU Period | 1 | 2 | 3 |
| 3-mo | |||
| PSI (overall satisfaction w/ op) | 94.6 | 76.9* | 79.4 |
| satisfaction w/ pain reduction | 97.3 | 66.7† | 79.4* |
| satisfaction w/ improved performance | 86.5 | 66.7 | 70.6 |
| 6-mo | |||
| PSI (overall satisfaction w/ op) | 89.5 | 80.0 | 77.1 |
| satisfaction w/ pain reduction | 94.7 | 75.0* | 82.9 |
| satisfaction w/ improved performance | 78.9 | 77.1 | 71.4 |
| 12-mo | |||
| PSI (overall satisfaction w/ op) | 97.3 | 74.4† | 73.5† |
| satisfaction w/ pain reduction | 100 | 71.8‡ | 73.5‡ |
| satisfaction w/ improved performance | 83.8 | 69.2 | 61.8 |
* p < 0.05 compared with Group 1.
† p < 0.01 compared with Group 1.
‡ p < 0.001 compared with Group 1.
Postoperative CT scanning demonstrated adequate decompression in all patients, and in no patient was reoperation required for residual or recurrent spinal stenosis at the same segment(s) within 12 to 18 months. Adjacent-level stenosis requiring decompression occurred in one Group 3 patient. Facet joint denervation was successfully performed in two patients who presented with lumbar facet syndrome. In five patients (three in Group 3 and two in Group 2) postoperative instability developed requiring instrumentation assisted fusion. Overall, the reoperation rate did not differ among groups (Table 7).
| Group (%) | |||
|---|---|---|---|
| 1 | 2 | 3 | |
| no. of cases | |||
| facet joint denervation | 1 (2.7) | 1 (2.6) | 0 (0.0) |
| same-level decompression | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| adjacent-level decompression | 0 (0.0) | 0 (0.0) | 1 (2.9) |
| instrumented fusion | 0 (0.0) | 2 (5.1) | 3 (8.8) |
| total | 1 (2.7) | 3 (7.7) | 4 (11.8) |
When clinical outcome is viewed by ranking the results according to each parameter a striking superiority is demonstrated in cases treated by bilateral laminotomy compared with laminectomy and unilateral laminotomy, although all three procedures dramatically improved clinical symptoms. The latter two approaches yielded comparable results (Table 8).
| Group (%) | |||
|---|---|---|---|
| Parameter | 1 | 2 | 3 |
| no. of periop complications | 1 | 2 | 3* |
| pain | |||
| overall pain | 1 | 2* | 3* |
| pain relief | |||
| LBP at rest | 1 | 3 | 2 |
| LBP during walking | 1 | 2* | 3 |
| leg pain at rest | 1 | 2* | 3* |
| leg pain during walking | 1 | 2* | 3* |
| total | 1 | 2 | 3 |
| disability | |||
| RMS score | 1 | 3 | 2 |
| walking distance | 1 | 3 | 2 |
| total | 1 | 3 | 2 |
| health-related QOL (SF-36 subscales) | |||
| physical functioning | 1 | 3* | 2 |
| role-physical functioning | 1 | 3 | 2 |
| bodily pain | 1 | 2* | 3* |
| general health perception | 1 | 2* | 3 |
| vitality | 1 | 3* | 2 |
| social functioning | 1 | 3* | 2 |
| role-emotional functioning | 1 | 3 | 2 |
| mental health index | 1 | 3 | 2 |
| physical component summary | 1 | 3* | 2 |
| mental component summary | 2 | 3 | 1 |
| total | 1 | 3 | 2 |
| patient satisfaction | |||
| PSI (overall satisfaction w/ op) | 1 | 2* | 3* |
| satisfaction w/ pain reduction | 1 | 3* | 2* |
| satisfaction w/ improved performance | 1 | 2 | 3 |
| self-reported success rate | 1 | 3* | 2* |
| total | 1 | 2 | 2 |
| no. of reops | 1 | 2 | 3 |
* The difference is statistically significant compared with Group 1 (p < 0.05); no significant difference was demonstrated between Groups 2 and 3 for any parameter.
We have presented the results of the first randomized prospective study to compare the safety and outcome of uni- and bilateral laminotomy compared with laminectomy in 120 patients with lumbar spinal stenosis. The incidence of complications did not differ significantly among groups, whereas overall perioperative morbidity was lowest after bilateral laminotomy. All three procedures yielded highly significant improvement in symptoms and scores; however, significantly superior outcome was demonstrated after bilateral laminotomy.
Acquired lumbar stenosis is the most common indication for lumbar spinal surgery in elderly patients (age > 65 years) and will continue to gain in importance as life expectancy increases and perioperative management improves.34,75,81 Decompressive laminectomy is the standard surgical treatment in these patients,2,6,39,45,46,80,81 but according to the results of a metaanalysis, it was successful in only 64% of the cases.81 In particular, spinal instability has been implicated as a cause of surgical failures,26,42,56,71,79 because wide posterior decompression significantly alters spinal anatomy and biomechanics,16,22,62,94 thus prompting many spine surgeons to perform fusion procedures to treat lumbar stenosis.47,51 Although numerous studies have been conducted to address the impact of (instrumentation-augmented) fusion on outcome, overall results after decompression alone have not been surpassed.30,58,82 The frequency of fusion surgery, however, has been steadily increasing in the treatment of degenerative lumbar disease despite numerous concerns.53
Instead of combining fusion with decompression and thus maximizing surgery and associated perioperative risks, other investigators have attempted to decrease the operative failure rate by minimizing the invasiveness of the decompressive procedure. Partial (interspinous) laminectomies25,38,67,69 have been introduced as well as modifications involving spinous process osteotomies.32,33,86 To spare the dorsal midline structures completely in contrast to laminectomy techniques, fenestration or laminotomy has also been propagated. Of the various decompressive techniques, encouraging results have been reported particularly for bilateral laminotomy4,50,57,78,91,93 and unilateral laminotomy in which contralateral decompression is achieved by undercutting the spinous process.31,49,55,59,60,73,74,87 We therefore undertook a randomized study of these two newer techniques in which they were compared with laminectomy. The latter was performed with maximal preservation of the facet joints.16,44
Acquired lumbar stenosis often coincides with other consequences of spinal degeneration such as disc prolapse and instability, resulting in a heterogeneous patient population. Consequently, it has been suggested that the procedure should be tailored to each patient depending on symptoms and imaging findings—for example, unilateral approaches in cases of unilateral symptoms and/or discogenic nerve root compression.11,40 The authors of previous studies of decompressive techniques have commonly neglected the heterogeneity of the patient population by allowing limitation of surgery to unilateral decompression,11,28,37,54,66 and including cases in which discectomies5,30,35,37,49,52,54,57,59,61,66,74,78 and/or even fusions5,13,30,37,45,46,61,63,65 were performed at the discretion of the surgeon. This may, of course, reflect the patient's individual situation, but it prevents the drawing of solid conclusions regarding the efficacy of the studied decompressive procedure. This is one of the reasons why there is no existing clinical study in which a clear clinical advantage of one technique over the other is shown in the treatment of lumbar stenosis.7
To minimize the heterogeneity of the patient population, factors affecting outcome such as spinal instability or discogenic neural compression were excluded in the presented study. Noncompressive disc protrusions, which are abundant in these patients, were not an exclusion criterion, but at surgery we determined that a small number of patients would be excluded for later outcome analysis, because a disc protrusion was found to cause nerve compression and to require discectomy. Defining instability is an ongoing matter of debate,79,92 and multiple definitions have been proposed. Although various factors seem to be of importance, most clinicians rely on certain thresholds for sagittal motion on flexion—extension radiography. We have therefore used a rather simple definition of spinal instability without excluding cases of stable spondylolisthesis.23,89 According to that definition, five patients in our series required fusion for symptomatic instability within 1 year of decompression and in all cases some sagittal-plane displacement without hypermobility was demonstrated preoperatively. Further follow-up evaluation in our patients may thus reveal that other radiological neuroimaging parameters should be added to define overall spinal instability.
In the present study we recruited elderly patients who almost all (117 of 120) suffered from rather severe neurogenic claudication refractory to conservative treatment. Demographic, clinical (for example, severity of the disease), and psychological (for instance, depression) factors potentially influencing outcome were assessed in a standardized fashion and were found to be evenly distributed among the randomized groups. Randomization also eliminates the relationship between rates (regional variations due to differing indications for surgery) and outcomes after operative treatment for lumbar stenosis, which makes comparisons of outcome studies difficult.48
This is the first study to demonstrate that adequate decompression could be achieved using the scheduled laminotomy technique regardless of the severity of stenosis. No conversion to laminectomy was performed, which had limited the power of previous studies.61 Obviously, the skin incision was longest in Group 3 and shortest in Group 2, which underscores the less invasive nature of the laminotomy approaches. Because all procedures were performed microscopically, however, the mean difference amounted to only 1.0 to 1.5 cm/level. Pertinent data in the literature are scarce,59 although the importance of the cosmetic result has been stressed.87 Blood loss was reduced in the unilateral laminotomy group,49,59 but clinically detrimental EBL requiring transfusion is very rare in all decompressive procedures of lumbar stenosis.18,61
Laminectomy is considered a simple and fast decompressive technique,77,87 whereas bilateral laminotomy has been associated with a longer operative duration61,70 and the unilateral approach has been deemed technically more challenging.87 In our study, the duration of surgery proved to be increased in Group 1. There was no significant difference between Groups 2 and 3. Khoo and Fessler49 reported an operative duration of 109 minutes for a single-level microendoscopic unilateral laminotomy and 88 minutes for open laminectomy.49 Others have reported shorter operative times for laminectomies,27 but data on laminectomy in which the facet joints are meticulously spared are scarce. Overall, our results are comparable with those reported in the literature.49,59,61,74 Unilateral laminotomy was rated technically much more demanding than bilateral laminotomy or laminectomy, whereas the latter two received a similar rating. This, however, did not translate in increased operative time, EBL, or perioperative morbidity compared with laminectomy.
The first step in evaluating a new technique or procedure consists of analyzing its safety compared with the current standard of care. This is mandatory when assessing a novel surgical treatment of a disease, such as lumbar stenosis that is prevalent in an elderly population, which is thought to be prone to perioperative morbidity.12,18,27 The authors of clinical series involving uni- or bilateral laminotomy have reported complication rates lower than or comparable with laminectomy,5,11,20,50,74,78,93 but the sizes of populations have been small and the studies were mostly retrospective or lacked a control group. In comparative studies, however, investigators revealed an increase in perioperative morbidity, namely neurological sequelae. Therefore, the main concern of spine surgeons in view of less invasive techniques to decompress lumbar stenosis has been an increased rate of neural injury.7,24,61,70,77 In the series reported by Verbiest,83 a postoperative increased radicular deficit was observed in 5% of laminectomytreated cases, whereas this complication has been rarely reported since.61 Postacchini, et al., 61 reported a postoperative increase in radiculopathy in one (1.3%) of 32 patients after laminectomy compared with three (11.5%) of 26 patients after bilateral laminotomy, whereas others have reported this complication in only 1% when using the latter approach.5 According to our data, actual injury to a nerve root did not occur. Intraoperative manipulation and/or compression of nerve roots, however, may provoke radicular deficit. Both patients with these deficits affected in our study suffered from longlasting diabetes complicated by polyneuropathy and they presented preoperatively with a sensorimotor deficit. A higher incidence of complications and neurological dysfunction has been documented in patients with diabetes following decompression of lumbar stenosis.3
Unintended durotomy is another concern during spinal decompressive procedures, although no association with long-term sequelae has been found.9,72,84 Wang, et al.,84 reported an incidence of 13% for first-time stenosis surgery managed by direct suture repair and wound drainage. In using this management strategy without suction drainage postoperative CSF leaks were eliminated in our series. Overall, durotomy rates for laminectomy have been shown to range from 5 to 15%.21,49,72,81,84 Bilateral laminotomy is complicated by dural tears in 2 to 6%5,50,78,93 and unilateral laminotomy with contralateral decompression in 3.5 to 12%.20,59,74 The unilateral microendoscopic approach is associated with an incidence of 16% (four of 25 patients).49 The results of the present study are in accordance with those in the literature, underscoring that bilateral laminotomy carries a very low risk of unintended durotomy, which may be somewhat higher in the technically demanding unilateral approach.
The wound infection rate is approximately 2% of all spinal surgery cases,72,88 and this complication was also rare in our study (0.8%). For postoperative epidural hematomas, the incidence ranges from 1 to 3%.72,93 This was somewhat surpassed in the laminectomy and unilateral laminotomy groups. Although contralateral control of epidural veins may be problematic in some unilateral procedures, the incidence of postoperative hematomas after bilateral laminotomy should not differ from the low rates after microdiscectomy, which corresponds well with our data.
In summary, the less invasive techniques are neither associated with an increased rate of postoperative nerve deficits nor a higher rate of other complications compared with laminectomy. On the contrary, bilateral laminotomy was associated with the lowest complication rate.
Attempts to analyze the literature to identify the optimal surgical procedure for acquired lumbar stenosis by using metaanalysis or Cochrane Review proved very challenging because measuring outcomes in musculoskeletal disorders is extremely problematic95 and outcome variables as well as definition of (good/bad) outcome varied considerably among studies.29,58,81 Therefore, being a comparison of the efficacy of decompressive procedures for lumbar stenosis based on the analysis of several independent studies is hardly possible. To overcome this shortcoming, standardized assessment of analog pain, disability, health-related QOL, and patient satisfaction scales—that is, patient-derived outcome measures—has been called for.8,17,75,81 In the present study, analysis of outcome was based on the VAS for pain, the RMS for disability, the SF-36 for health-related QOL, and the PSI, which should simplify comparison with other studies. Surgeon-based outcome measures were neglected. More importantly, however, the randomized study design minimized conceptual errors in the comparison of outcome among groups.
Another important variable for assessment of outcome is follow-up duration, as deterioration of results following spinal surgery has been repeatedly reported to occur within the 1st postoperative year41, and/or thereafter.10,72,80 In our study, a minimum follow-up period of 12 months was available for all patients. Symptoms and scores remained stable during that period. Nevertheless, long-term follow-up data are mandatory and will be pursued.
As mentioned previously, laminectomy is associated with improvement in 64% of patients at 3 to 6 years after surgery according to a metaanalysis.81 The authors of a study that used standardized patient-derived measures of symptom relief 4 years after decompression reported a success rate of just 57%.46 In a large retrospective study, Airaksinen, et al.,2 found good outcomes after 4 years in 62% of their 438 patients, whereas others have described satisfactory results in approximately 70%.41,72 In a literature review Herron and Mangelsdorf37 reported rates of good outcome ranging from 50 to 86% and stressed that results deteriorated over time. In the present study, the rate of patient satisfaction, self-reported success, and improvement of neurogenic claudication after laminectomy was 70%, which is in accordance with that in the literature. Regardless of meticulous sparing of the facet joints, instrumentation-assisted fusion was required in 9% of patients due to postoperative instability within the first 18 postoperative months.
In the goal to refine minimally invasive procedures, the unilateral approach for bilateral decompression, also termed the “ipsi-contra” procedure,40 was developed as an alternative to laminectomies.31,60 Although technically demanding,87 high success rates of 88% (in 22 of 25 patients),74 68% (in 15 of 22),55 and 87% (in 26 of 30)87 have been reported. In combination with contralateral fusion, the success rate was 69%.20 Khoo and Fessler49 compared data obtained in 25 patients in whom decompression was performed via microendoscopic unilateral approach with those acquired in 25 who underwent laminectomy. Success rates in both groups were nearly 90%. Most of the aforementioned studies, however, are characterized by only short-term follow-up periods, small patient populations, and the lack of a control group which limit the power of their conclusions. In the present study, we found no benefit to the unilateral laminotomy compared with laminectomy (success rates ∼ 70%). Interestingly, unilateral laminotomy was superior to laminectomy in terms of improving leg pain but inferior in terms of low-back pain, although these differences were not statistically significant. Why the asymmetrical approach leaves more residual pain, particularly in the low back, compared with the bilateral laminotomy, remains unclear. Residual canal compromise can be excluded as causing unsatisfactory results in the present study because adequacy of decompression was evaluated on postoperative CT scanning in all patients. Despite minimal removal of bone, postoperative instability was demonstrated in 5% of the patients during the follow-up period.
Following the description of the bilateral laminotomy technique,52 the authors of clinical case series demonstrated good results in 91% (29 of 32 patients)4 at 1 year; 82% (28 of 34),57 87% (13 of 15),30 78% (21 of 27),92 and 68% (34 of 50 patients)78 at 2 years; 85% (27 of 32)93 at 3 years; and 74% (76 of 102 patients)5 at 6 years. When performing a limited decompression by laminotomy tailored to the individual symptoms (uni- or bilateral) some surgeons have reported success rates of 60 to 80%.11,28,54,66 These encouraging results compared favorably with those of laminectomy. As previously stated, however, retrospective study designs, inclusion of fusion surgery as well as discectomies, and insufficient outcome measures limit the reliability of these studies. Additionally, deterioration of results was documented over time.65,91 In a prospective outcome study of 54 patients, Kleeman, et al.,50 in contrast, reported good outcome in 88% and patient satisfaction in 100% after 4 years without deterioration.
Controlled studies involving laminotomy techniques are scarce. Thomas, et al.,76 and Kalbarczyk, et al.,43 retrospectively compared bilateral laminotomy and laminectomy and found no difference in outcome. The same was true for the prospective nonrandomized comparison published by Postacchini, et al.,61 and Delank, et al.15 The study protocols, however, were open allowing intraoperative change of procedure61 or even free choice of procedure.15
In the present randomized study, the success rate of bilateral laminotomy was 80%, its improvement rate was 92% and patient satisfaction was 97% during the 12- to 18-month follow-up period, which supports the data of the aforementioned case series. These results are significantly superior to laminectomy and/or unilateral laminotomy. Other outcome parameters, such as overall pain and health-related QOL, support this conclusion. Fusion was not indicated in any patient. If analysis of long-term follow-up data confirms these results, bilateral laminotomy may prove advantageous for patients with lumbar stenosis, reducing the need for additional fusion surgery.
Bilateral and unilateral laminotomy allow adequate and safe decompression of the spinal canal in patients with lumbar stenosis. These limited decompression procedures resulted in a highly significant reduction of symptoms and disability and improve health-related QOL. Outcome after unilateral laminotomy is comparable with that after laminectomy. Bilateral laminotomy was associated with a significant benefit in most outcome parameters during a minimum follow-up period of 12 months and thus constitutes a promising treatment alternative.
We thank Johann Scharf, M.D., and the Department of Neuroradiology, University Hospital Mannheim, Faculty for Clinical Medicine of the Karl-Ruprecht-University of Heidelberg for their assistance in preparing the three-dimensional reconstructions of the CT scans. We also thank Axel Grüner and Hubertus Frank, M.D., for collection and processing of the data.
Allgemeine Depressionsskala
cerebrospinal fluid
computerized tomography
estimated blood loss
magnetic resonance
North American Spine Society
not significant
Patient Satisfaction Index
quality of life
Roland—Morris Scale
standard deviation
Short Form-36
visual analog scale
References
- 1.↑
Airaksinen OHerno AKaukanen ESaari TSihvonen TSuomalainen O: Density of lumbar muscles 4 years after decompressive spinal surgery. Eur Spine J 5:193–1971996Airaksinen O Herno A Kaukanen E Saari T Sihvonen T Suomalainen O: Density of lumbar muscles 4 years after decompressive spinal surgery. Eur Spine J 5:193–197 1996
- 2.↑
Airaksinen OHerno ATurunen VSaari TSuomlainen O: Surgical outcome of 438 patients treated surgically for lumbar spinal stenosis. Spine 22:2278–22821997Airaksinen O Herno A Turunen V Saari T Suomlainen O: Surgical outcome of 438 patients treated surgically for lumbar spinal stenosis. Spine 22:2278–2282 1997
- 3.↑
Arinzon ZAdunsky AFidelman ZGepstein R: Outcomes of decompression surgery for lumbar spinal stenosis in elderly diabetic patients. Eur Spine J 13:32–372004Arinzon Z Adunsky A Fidelman Z Gepstein R: Outcomes of decompression surgery for lumbar spinal stenosis in elderly diabetic patients. Eur Spine J 13:32–37 2004
- 4.↑
Aryanpur JDucker T: Multilevel lumbar laminotomies: an alternative to laminectomy in the treatment of lumbar stenosis. Neurosurgery 26:429–4331990Aryanpur J Ducker T: Multilevel lumbar laminotomies: an alternative to laminectomy in the treatment of lumbar stenosis. Neurosurgery 26:429–433 1990
- 5.↑
Askar ZWardlaw DChoudhary SRege A: A ligamentum flavum-preserving approach to the lumbar spinal canal. Spine 28:E385–E3902003Askar Z Wardlaw D Choudhary S Rege A: A ligamentum flavum-preserving approach to the lumbar spinal canal. Spine 28:E385–E390 2003
- 6.↑
Atlas SJDeyo RAKeller RBChapin AMPatrick DLLong JMet al: The Maine Lumbar Spine Study, Part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis. Spine 21:1787–17951996Atlas SJ Deyo RA Keller RB Chapin AM Patrick DL Long JM et al: The Maine Lumbar Spine Study Part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis. Spine 21:1787–1795 1996
- 7.↑
Benz RJGarfin SR: Current techniques of decompression of the lumbar spine. Clin Orthop Relat Res 384:75–812001Benz RJ Garfin SR: Current techniques of decompression of the lumbar spine. Clin Orthop Relat Res 384:75–81 2001
- 8.↑
Blount KJKrompinger WJMaljanian RBrowner BD: Moving toward a standard for spinal fusion outcomes assessment. J Spinal Disord Tech 15:16–232002Blount KJ Krompinger WJ Maljanian R Browner BD: Moving toward a standard for spinal fusion outcomes assessment. J Spinal Disord Tech 15:16–23 2002
- 9.↑
Cammisa FP JrGirardi FPSangani PKParvataneni HKCadag SSandhu HS: Incidental durotomy in spine surgery. Spine 25:2663–26672000Cammisa FP Jr Girardi FP Sangani PK Parvataneni HK Cadag S Sandhu HS: Incidental durotomy in spine surgery. Spine 25:2663–2667 2000
- 10.↑
Caputy AJLuessenhop AJ: Long-term evaluation of decompressive surgery for degenerative lumbar stenosis. J Neurosurg 77:669–6761992Caputy AJ Luessenhop AJ: Long-term evaluation of decompressive surgery for degenerative lumbar stenosis. J Neurosurg 77:669–676 1992
- 11.↑
Caspar WPapavero LSayler MKHarkey HL: Precise and limited decompression for lumbar spinal stenosis. Acta Neurochir 131:130–1361994Caspar W Papavero L Sayler MK Harkey HL: Precise and limited decompression for lumbar spinal stenosis. Acta Neurochir 131:130–136 1994
- 12.↑
Ciol MADeyo RAHowell EKreif S: An assessment of surgery for spinal stenosis: time trends, geographic variations, complications, and reoperations. J Am Geriatr Soc 44:285–2901996Ciol MA Deyo RA Howell E Kreif S: An assessment of surgery for spinal stenosis: time trends geographic variations complications and reoperations. J Am Geriatr Soc 44:285–290 1996
- 13.↑
Cornefjord MByrod GBrisby HRydevik B: A long-term (4- to 12-year) follow-up study of surgical treatment of lumbar spinal stenosis. Eur Spine J 9:563–5702000Cornefjord M Byrod G Brisby H Rydevik B: A long-term (4- to 12-year) follow-up study of surgical treatment of lumbar spinal stenosis. Eur Spine J 9:563–570 2000
- 14.↑
Daltroy LHCats-Baril WLKatz JNFossel AHLiang MH: The North American spine society lumbar spine outcome assessment Instrument: reliability and validity tests. Spine 21:741–7491996Daltroy LH Cats-Baril WL Katz JN Fossel AH Liang MH: The North American spine society lumbar spine outcome assessment Instrument: reliability and validity tests. Spine 21:741–749 1996
- 15.↑
Delank KSEysel PZollner JDrees PNafe BRompe JD: [Undercutting decompression versus laminectomy. Clinical and radiological results of a prospective controlled trial.] Orthopade 31:1048–10572002 (Ger)Delank KS Eysel P Zollner J Drees P Nafe B Rompe JD: [Undercutting decompression versus laminectomy. Clinical and radiological results of a prospective controlled trial.] Orthopade 31:1048–1057 2002 (Ger)
- 16.↑
Detwiler PWSpetzler CBTaylor SBCrawford NRPorter RWSonntag VK: Biomechanical comparison of facet-sparing laminectomy and Christmas tree laminectomy. J Neurosurg (Spine 2) 99:214–2202003Detwiler PW Spetzler CB Taylor SB Crawford NR Porter RW Sonntag VK: Biomechanical comparison of facet-sparing laminectomy and Christmas tree laminectomy. J Neurosurg (Spine 2) 99:214–220 2003
- 17.↑
Deyo RABattie MBeurskens AJBombardier CCroft PKoes Bet al: Outcome measures for low back pain research. A proposal for standardized use. Spine 23:2003–20131998Deyo RA Battie M Beurskens AJ Bombardier C Croft P Koes B et al: Outcome measures for low back pain research. A proposal for standardized use. Spine 23:2003–2013 1998
- 18.↑
Deyo RACherkin DCLoeser JDBigos SJCiol MA: Morbidity and mortality in association with operations on the lumbar spine. The influence of age, diagnosis, and procedure. J Bone Joint Surg Am 74:536–5431992Deyo RA Cherkin DC Loeser JD Bigos SJ Ciol MA: Morbidity and mortality in association with operations on the lumbar spine. The influence of age diagnosis and procedure. J Bone Joint Surg Am 74:536–543 1992
- 19.↑
Deyo RANachemson AMirza SK: Spinal-fusion surgery—the case for restraint. N Engl J Med 350:722–7262004Deyo RA Nachemson A Mirza SK: Spinal-fusion surgery—the case for restraint. N Engl J Med 350:722–726 2004
- 20.↑
diPierro CGHelm GAShaffrey CIChadduck JBHenson SLMalik JMet al: Treatment of lumbar spinal stenosis by extensive unilateral decompression and contralateral autologous bone fusion: operative technique and results. J Neurosurg 84:166–1731996diPierro CG Helm GA Shaffrey CI Chadduck JB Henson SL Malik JM et al: Treatment of lumbar spinal stenosis by extensive unilateral decompression and contralateral autologous bone fusion: operative technique and results. J Neurosurg 84:166–173 1996
- 21.↑
Dujovny MAgner C: The use of high power drills for laminectomy in spinal stenosis: technical report. Neurol Res 19:219–2211997Dujovny M Agner C: The use of high power drills for laminectomy in spinal stenosis: technical report. Neurol Res 19:219–221 1997
- 22.↑
Efstathiou PMoskovich RCasar RMagnisalis E: A biomechanical evaluation of internal lumbar laminoplasty: the preservation of spinal stability during laminectomy for degenerative spinal stenosis. Bull Hosp Jt Dis 55:7–111996Efstathiou P Moskovich R Casar R Magnisalis E: A biomechanical evaluation of internal lumbar laminoplasty: the preservation of spinal stability during laminectomy for degenerative spinal stenosis. Bull Hosp Jt Dis 55:7–11 1996
- 23.↑
Epstein NE: Decompression in the surgical management of degenerative spondylolisthesis: advantages of a conservative approach in 290 patients. J Spinal Disord 11:116–1231998Epstein NE: Decompression in the surgical management of degenerative spondylolisthesis: advantages of a conservative approach in 290 patients. J Spinal Disord 11:116–123 1998
- 24.↑
Epstein NEMaldonado VCCusick JF: Symptomatic lumbar spinal stenosis. Surg Neurol 50:3–101998Epstein NE Maldonado VC Cusick JF: Symptomatic lumbar spinal stenosis. Surg Neurol 50:3–10 1998
- 25.↑
Eule JMBreeze RKindt GW: Bilateral partial laminectomy: a treatment for lumbar spinal stenosis and midline disc herniation. Surg Neurol 52:329–3381999Eule JM Breeze R Kindt GW: Bilateral partial laminectomy: a treatment for lumbar spinal stenosis and midline disc herniation. Surg Neurol 52:329–338 1999
- 26.↑
Fox MWOnofrio BMHanssen 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 85:793–8021996Fox MW 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 85:793–802 1996
- 27.↑
Fredman BArinzon ZZohar EShabat SJedeikin RFidelman ZGet al: Observations on the safety and efficacy of surgical decompression for lumbar spinal stenosis in geriatric patients. Eur Spine J 11:571–5742002Fredman B Arinzon Z Zohar E Shabat S Jedeikin R Fidelman ZG et al: Observations on the safety and efficacy of surgical decompression for lumbar spinal stenosis in geriatric patients. Eur Spine J 11:571–574 2002
- 28.↑
Getty CJJohnson JRKirwan EOSullivan MF: Partial undercutting facetectomy for bony entrapment of the lumbar nerve root. J Bone Joint Surg Br 63:330–3351981Getty CJ Johnson JR Kirwan EO Sullivan MF: Partial undercutting facetectomy for bony entrapment of the lumbar nerve root. J Bone Joint Surg Br 63:330–335 1981
- 29.↑
Gibson JNGrant ICWaddell G: The Cochrane review of surgery for lumbar disc prolapse and degenerative lumbar spondylosis. Spine 24:1820–18321999Gibson JN Grant IC Waddell G: The Cochrane review of surgery for lumbar disc prolapse and degenerative lumbar spondylosis. Spine 24:1820–1832 1999
- 30.↑
Grob DHumke TDvorak J: Degenerative lumbar spinal stenosis. Decompression with and without arthrodesis. J Bone Joint Surg Am 77:1036–10411995Grob D Humke T Dvorak J: Degenerative lumbar spinal stenosis. Decompression with and without arthrodesis. J Bone Joint Surg Am 77:1036–1041 1995
- 31.↑
Guiot BHKhoo LTFessler RG: A minimally invasive technique for decompression of the lumbar spine. Spine 27:432–4382002Guiot BH Khoo LT Fessler RG: A minimally invasive technique for decompression of the lumbar spine. Spine 27:432–438 2002
- 32.↑
Gunzburg RKeller TSSzpalski MVandeputte KSpratt KF: Clinical and psychofunctional measures of conservative decompression surgery for lumbar spinal stenosis: a prospective cohort study. Eur Spine J 12:197–2042003Gunzburg R Keller TS Szpalski M Vandeputte K Spratt KF: Clinical and psychofunctional measures of conservative decompression surgery for lumbar spinal stenosis: a prospective cohort study. Eur Spine J 12:197–204 2003
- 33.↑
Gunzburg RKeller TSSzpalski MVandeputte KSpratt KF: A prospective study on CT scan outcomes after conservative decompression surgery for lumbar spinal stenosis. J Spinal Disord Tech 16:261–2672003Gunzburg R Keller TS Szpalski M Vandeputte K Spratt KF: A prospective study on CT scan outcomes after conservative decompression surgery for lumbar spinal stenosis. J Spinal Disord Tech 16:261–267 2003
- 34.↑
Gunzburg RSzpalski M: The conservative surgical treatment of lumbar spinal stenosis in the elderly. Eur Spine J 12 (Suppl 2):S176–S1802003Gunzburg R Szpalski M: The conservative surgical treatment of lumbar spinal stenosis in the elderly. Eur Spine J 12 (Suppl 2):S176–S180 2003
- 35.↑
Hansraj KKCammisa FP JrO'Leary PFCrockett HCFras CICohen MSet al: Decompressive surgery for typical lumbar spinal stenosis. Clin Orthop 384:10–172001Hansraj KK Cammisa FP Jr O'Leary PF Crockett HC Fras CI Cohen MS et al: Decompressive surgery for typical lumbar spinal stenosis. Clin Orthop 384:10–17 2001
- 36.↑
Hautzinger MBailer M: Allgemeine Depressionsskala. Weinheim: Beltz Test1993Hautzinger M: Bailer M: Allgemeine Depressionsskala. Weinheim: Beltz Test 1993
- 37.↑
Herron LDMangelsdorf C: Lumbar spinal stenosis: results of surgical treatment. J Spinal Disord 4:26–331991Herron LD Mangelsdorf C: Lumbar spinal stenosis: results of surgical treatment. J Spinal Disord 4:26–33 1991
- 38.↑
Herron LDPheasant HC: Bilateral laminotomy and discectomy for segmental lumbar disc disease. Decompression with stability. Spine 8:86–971983Herron LD Pheasant HC: Bilateral laminotomy and discectomy for segmental lumbar disc disease. Decompression with stability. Spine 8:86–97 1983
- 39.↑
Iguchi TKurihara ANakayama JSato KKurosaka MYamasaki K: Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine 25:1754–17592000Iguchi T Kurihara A Nakayama J Sato K Kurosaka M Yamasaki K: Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine 25:1754–1759 2000
- 40.↑
Jane JA SrSherman JHBoulos PTLuce CDumont AS: Lumbar stenosis: a personal record. Invited submission from the Joint Section Meeting of Disorders of the Spine and Peripheral Nerves, March 2004. J Neurosurg Spine 11:31–382004Jane JA Sr Sherman JH Boulos PT Luce C Dumont AS: Lumbar stenosis: a personal record. Invited submission from the Joint Section Meeting of Disorders of the Spine and Peripheral Nerves March 2004. J Neurosurg Spine 11:31–38 2004
- 41.↑
Javid MJHadar EJ: Long-term follow-up review of patients who underwent laminectomy for lumbar stenosis: a prospective study. J Neurosurg 89:1–71998Javid MJ Hadar EJ: Long-term follow-up review of patients who underwent laminectomy for lumbar stenosis: a prospective study. J Neurosurg 89:1–7 1998
- 42.↑
Johnsson KEWillner SJohnsson K: Postoperative instability after decompression for lumbar spinal stenosis. Spine 11:107–1101986Johnsson KE Willner S Johnsson K: Postoperative instability after decompression for lumbar spinal stenosis. Spine 11:107–110 1986
- 43.↑
Kalbarczyk ALukes ASeiler RW: Surgical treatment of lumbar spinal stenosis in the elderly. Acta Neurochir 140:637–6411998Kalbarczyk A Lukes A Seiler RW: Surgical treatment of lumbar spinal stenosis in the elderly. Acta Neurochir 140:637–641 1998
- 44.↑
Kanamori MMatsui HHirano NKawaguchi YKitamoto RTsuji H: Trumpet laminectomy for lumbar degenerative spinal stenosis. J Spinal Disord 6:232–2371993Kanamori M Matsui H Hirano N Kawaguchi Y Kitamoto R Tsuji H: Trumpet laminectomy for lumbar degenerative spinal stenosis. J Spinal Disord 6:232–237 1993
- 45.↑
Katz JNLipson SJChang LCLevine SAFossel AHLiang MH: Seven- to 10-year outcome of decompressive surgery for degenerative lumbar spinal stenosis. Spine 21:92–981996Katz JN Lipson SJ Chang LC Levine SA Fossel AH Liang MH: Seven- to 10-year outcome of decompressive surgery for degenerative lumbar spinal stenosis. Spine 21:92–98 1996
- 46.↑
Katz JNLipson SJLarson MGMcInnes JMFossel AHLiang MH: The outcome of decompressive laminectomy for degenerative lumbar stenosis. J Bone Joint Surg Am 73:809–8161991Katz JN Lipson SJ Larson MG McInnes JM Fossel AH Liang MH: The outcome of decompressive laminectomy for degenerative lumbar stenosis. J Bone Joint Surg Am 73:809–816 1991
- 47.↑
Katz JNLipson SJLew RAGrobler LJWeinstein JNBrick GWet al: Lumbar laminectomy alone or with instrumented or noninstrumented arthrodesis in degenerative lumbar spinal stenosis. Patient selection, costs, and surgical outcomes. Spine 22:1123–11311997Katz JN Lipson SJ Lew RA Grobler LJ Weinstein JN Brick GW et al: Lumbar laminectomy alone or with instrumented or noninstrumented arthrodesis in degenerative lumbar spinal stenosis. Patient selection costs and surgical outcomes. Spine 22:1123–1131 1997
- 48.↑
Keller RBAtlas SJSoule DNSinger DEDeyo RA: Relationship between rates and outcomes of operative treatment for lumbar disc herniation and spinal stenosis. J Bone Joint Surg Am 81:752–7621999Keller RB Atlas SJ Soule DN Singer DE Deyo RA: Relationship between rates and outcomes of operative treatment for lumbar disc herniation and spinal stenosis. J Bone Joint Surg Am 81:752–762 1999
- 49.↑
Khoo LTFessler RG: Microendoscopic decompressive laminotomy for the treatment of lumbar stenosis. Neurosurgery 51 (Suppl 5):S146–S1542002Khoo LT Fessler RG: Microendoscopic decompressive laminotomy for the treatment of lumbar stenosis. Neurosurgery 51 (Suppl 5):S146–S154 2002
- 50.↑
Kleeman TJHiscoe ACBerg EE: Patient outcomes after minimally destabilizing lumbar stenosis decompression: the “Port-Hole” technique. Spine 25:865–8702000Kleeman TJ Hiscoe AC Berg EE: Patient outcomes after minimally destabilizing lumbar stenosis decompression: the “Port-Hole” technique. Spine 25:865–870 2000
- 51.↑
Korovessis PPapazisis ZKoureas GLambiris E: Rigid, semirigid versus dynamic instrumentation for degenerative lumbar spinal stenosis: a correlative radiological and clinical analysis of short-term results. Spine 29:735–7422004Korovessis P Papazisis Z Koureas G Lambiris E: Rigid semirigid versus dynamic instrumentation for degenerative lumbar spinal stenosis: a correlative radiological and clinical analysis of short-term results. Spine 29:735–742 2004
- 52.↑
Lin PM: Internal decompression for multiple levels of lumbar spinal stenosis: a technical note. Neurosurgery 11:546–5491982Lin PM: Internal decompression for multiple levels of lumbar spinal stenosis: a technical note. Neurosurgery 11:546–549 1982
- 53.↑
Lipson SJ: Spinal-fusion surgery—advances and concerns. N Engl J Med 350:643–6442004Lipson SJ: Spinal-fusion surgery—advances and concerns. N Engl J Med 350:643–644 2004
- 54.↑
Mackay DCWheelwright EF: Unilateral fenestration in the treatment of lumbar spinal stenosis. Br J Neurosurg 12:556–5581998Mackay DC Wheelwright EF: Unilateral fenestration in the treatment of lumbar spinal stenosis. Br J Neurosurg 12:556–558 1998
- 55.↑
Mariconda MFava RGatto ALongo CMilano C: Unilateral laminectomy for bilateral decompression of lumbar spinal stenosis: a prospective comparative study with conservatively treated patients. J Spinal Disord Tech 15:39–462002Mariconda M Fava R Gatto A Longo C Milano C: Unilateral laminectomy for bilateral decompression of lumbar spinal stenosis: a prospective comparative study with conservatively treated patients. J Spinal Disord Tech 15:39–46 2002
- 56.↑
Mullin BBRea GLIrsik RCatton MMiner ME: The effect of postlaminectomy spinal instability on the outcome of lumbar spinal stenosis patients. J Spinal Disord 9:107–1161996Mullin BB Rea GL Irsik R Catton M Miner ME: The effect of postlaminectomy spinal instability on the outcome of lumbar spinal stenosis patients. J Spinal Disord 9:107–116 1996
- 57.↑
Nakai OOokawa AYamaura I: Long-term roentgenographic and functional changes in patients who were treated with wide fenestration for central lumbar stenosis. J Bone Joint Surg Am 73:1184–11911991Nakai O Ookawa A Yamaura I: Long-term roentgenographic and functional changes in patients who were treated with wide fenestration for central lumbar stenosis. J Bone Joint Surg Am 73:1184–1191 1991
- 58.↑
Niggemeyer OStrauss JMSchulitz KP: Comparison of surgical procedures for degenerative lumbar spinal stenosis: a metaanalysis of the literature from 1975 to 1995. Eur Spine J 6:423–4291997Niggemeyer O Strauss JM Schulitz KP: Comparison of surgical procedures for degenerative lumbar spinal stenosis: a metaanalysis of the literature from 1975 to 1995. Eur Spine J 6:423–429 1997
- 59.↑
Palmer STurner RPalmer R: Bilateral decompression of lumbar spinal stenosis involving a unilateral approach with microscope and tubular retractor system. J Neurosurg (Spine 2) 97:213–2172002Palmer S Turner R Palmer R: Bilateral decompression of lumbar spinal stenosis involving a unilateral approach with microscope and tubular retractor system. J Neurosurg (Spine 2) 97:213–217 2002
- 60.↑
Poletti CE: Central lumbar stenosis caused by ligamentum flavum: unilateral laminotomy for bilateral ligamentectomy: preliminary report of two cases. Neurosurgery 37:343–3471995Poletti CE: Central lumbar stenosis caused by ligamentum flavum: unilateral laminotomy for bilateral ligamentectomy: preliminary report of two cases. Neurosurgery 37:343–347 1995
- 61.↑
Postacchini FCinotti GPerugia DGumina S: The surgical treatment of central lumbar stenosis. Multiple laminotomy compared with total laminectomy. J Bone Joint Surg Br 75:386–3921993Postacchini F Cinotti G Perugia D Gumina S: The surgical treatment of central lumbar stenosis. Multiple laminotomy compared with total laminectomy. J Bone Joint Surg Br 75:386–392 1993
- 62.↑
Quint UWilke HJLoer FClaes L: Laminectomy and functional impairment of the lumbar spine: the importance of muscle forces in flexible and rigid instrumented stabilization—a biomechanical study in vitro. Eur Spine J 7:229–2381998Quint U Wilke HJ Loer F Claes L: Laminectomy and functional impairment of the lumbar spine: the importance of muscle forces in flexible and rigid instrumented stabilization—a biomechanical study in vitro. Eur Spine J 7:229–238 1998
- 63.↑
Ragab AAFye MABohlman HH: Surgery of the lumbar spine for spinal stenosis in 118 patients 70 years of age or older. Spine 28:348–3532003Ragab AA Fye MA Bohlman HH: Surgery of the lumbar spine for spinal stenosis in 118 patients 70 years of age or older. Spine 28:348–353 2003
- 64.↑
Roland MMorris R: A study of the natural history of low-back pain. Part II: development of guidelines for trials of treatment in primary care. Spine 8:145–1501983Roland M Morris R: A study of the natural history of low-back pain. Part II: development of guidelines for trials of treatment in primary care. Spine 8:145–150 1983
- 65.↑
Rompe JDEysel PZollner JNafe BHeine J: Degenerative lumbar spinal stenosis. Long-term results after undercutting decompression compared with decompressive laminectomy alone or with instrumented fusion. Neurosurg Rev 22:102–1061999Rompe JD Eysel P Zollner J Nafe B Heine J: Degenerative lumbar spinal stenosis. Long-term results after undercutting decompression compared with decompressive laminectomy alone or with instrumented fusion. Neurosurg Rev 22:102–106 1999
- 66.↑
Sanderson PLGetty CJ: Long-term results of partial undercutting facetectomy for lumbar lateral recess stenosis. Spine 21:1352–13561996Sanderson PL Getty CJ: Long-term results of partial undercutting facetectomy for lumbar lateral recess stenosis. Spine 21:1352–1356 1996
- 67.↑
Schillberg BNystrom B: Quality of life before and after microsurgical decompression in lumbar spinal stenosis. J Spinal Disord 13:237–2412000Schillberg B Nystrom B: Quality of life before and after microsurgical decompression in lumbar spinal stenosis. J Spinal Disord 13:237–241 2000
- 68.↑
Scott JHuskisson EC: Graphic representation of pain. Pain 2:175–1841976Scott J Huskisson EC: Graphic representation of pain. Pain 2:175–184 1976
- 69.↑
Senegas JEtchevers JPVital JMBaulny DGrenier F: [Recalibration of the lumbar canal, an alternative to laminectomy in the treatment of lumbar canal stenosis.] Rev Chir Orthop Reparatrice Appar Mot 74:15–221988 (Fr)Senegas J Etchevers JP Vital JM Baulny D Grenier F: [Recalibration of the lumbar canal an alternative to laminectomy in the treatment of lumbar canal stenosis.] Rev Chir Orthop Reparatrice Appar Mot 74:15–22 1988 (Fr)
- 70.↑
Sengupta DKHerkowitz HN: Lumbar spinal stenosis. Treatment strategies and indications for surgery. Orthop Clin North Am 34:281–2952003Sengupta DK Herkowitz HN: Lumbar spinal stenosis. Treatment strategies and indications for surgery. Orthop Clin North Am 34:281–295 2003
- 71.↑
Sienkiewicz PJFlatley TJ: Postoperative spondylolisthesis. Clin Orthop 221:172–1801987Sienkiewicz PJ Flatley TJ: Postoperative spondylolisthesis. Clin Orthop 221:172–180 1987
- 72.↑
Silvers HRLewis PJAsch HL: Decompressive lumbar laminectomy for spinal stenosis. J Neurosurg 78:695–7011993Silvers HR Lewis PJ Asch HL: Decompressive lumbar laminectomy for spinal stenosis. J Neurosurg 78:695–701 1993
- 73.↑
Spetzger UBertalanffy HNaujokat Cvon Keyserlingk DGGilsbach JM: Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part I: Anatomical and surgical considerations. Acta Neurochir 139:392–3961997Spetzger U Bertalanffy H Naujokat C von Keyserlingk DG Gilsbach JM: Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part I: Anatomical and surgical considerations. Acta Neurochir 139:392–396 1997
- 74.↑
Spetzger UBertalanffy HReinges MHGilsbach JM: Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part II: Clinical experiences. Acta Neurochir 139:397–4031997Spetzger U Bertalanffy H Reinges MH Gilsbach JM: Unilateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part II: Clinical experiences. Acta Neurochir 139:397–403 1997
- 75.↑
Stucki GDaltroy LLiang MHLipson SJFossel AHKatz JN: Measurement properties of a self-administered outcome measure in lumbar spinal stenosis. Spine 21:796–8031996Stucki G Daltroy L Liang MH Lipson SJ Fossel AH Katz JN: Measurement properties of a self-administered outcome measure in lumbar spinal stenosis. Spine 21:796–803 1996
- 76.↑
Thomas NWRea GLPikul BKMervis LJIrsik RMcGregor JM: Quantitative outcome and radiographic comparisons between laminectomy and laminotomy in the treatment of acquired lumbar stenosis. Neurosurgery 41:567–5751997Thomas NW Rea GL Pikul BK Mervis LJ Irsik R McGregor JM: Quantitative outcome and radiographic comparisons between laminectomy and laminotomy in the treatment of acquired lumbar stenosis. Neurosurgery 41:567–575 1997
- 77.↑
Truumees EHerkowitz HN: Lumbar spinal stenosis: treatment options. Instr Course Lect 50:153–1612001Truumees E Herkowitz HN: Lumbar spinal stenosis: treatment options. Instr Course Lect 50:153–161 2001
- 78.↑
Tsai RYYang RSBray RS Jr: Microscopic laminotomies for degenerative lumbar spinal stenosis. J Spinal Disord 11:389–3941998Tsai RY Yang RS Bray RS Jr: Microscopic laminotomies for degenerative lumbar spinal stenosis. J Spinal Disord 11:389–394 1998
- 79.↑
Tuite GFDoran SEStern JDMcGillicuddy JEPapadopoulos SMLundquist CAet al: Outcome after laminectomy for lumbar spinal stenosis. Part II: Radiographic changes and clinical correlations. J Neurosurg 81:707–7151994Tuite GF Doran SE Stern JD McGillicuddy JE Papadopoulos SM Lundquist CA et al: Outcome after laminectomy for lumbar spinal stenosis. Part II: Radiographic changes and clinical correlations. J Neurosurg 81:707–715 1994
- 80.↑
Tuite GFStern JDDoran SEPapadopoulos SMMcGillicuddy JEOyedijo DIet al: Outcome after laminectomy for lumbar spinal stenosis. Part I: Clinical correlations. J Neurosurg 81:699–7061994Tuite GF Stern JD Doran SE Papadopoulos SM McGillicuddy JE Oyedijo DI et al: Outcome after laminectomy for lumbar spinal stenosis. Part I: Clinical correlations. J Neurosurg 81:699–706 1994
- 81.↑
Turner JAErsek MHerron LDeyo R: Surgery for lumbar spinal stenosis. Attempted meta-analysis of the literature. Spine 17:1–81992Turner JA Ersek M Herron L Deyo R: Surgery for lumbar spinal stenosis. Attempted meta-analysis of the literature. Spine 17:1–8 1992
- 82.↑
Turner JAErsek MHerron LHaselkorn JKent DCiol MAet al: Patient outcomes after lumbar spinal fusions. JAMA 268:907–9111992Turner JA Ersek M Herron L Haselkorn J Kent D Ciol MA et al: Patient outcomes after lumbar spinal fusions. JAMA 268:907–911 1992
- 83.↑
Verbiest H: Results of surgical treatment of idiopathic developmental stenosis of the lumbar vertebral canal. A review of twenty-seven years' experience. J Bone Joint Surg Br 59:181–1881977Verbiest H: Results of surgical treatment of idiopathic developmental stenosis of the lumbar vertebral canal. A review of twenty-seven years' experience. J Bone Joint Surg Br 59:181–188 1977
- 84.↑
Wang JCBohlman HHRiew KD: Dural tears secondary to operations on the lumbar spine. Management and results after a two-year-minimum follow-up of eighty-eight patients. J Bone Joint Surg Am 80:1728–17321998Wang JC Bohlman HH Riew KD: Dural tears secondary to operations on the lumbar spine. Management and results after a two-year-minimum follow-up of eighty-eight patients. J Bone Joint Surg Am 80:1728–1732 1998
- 85.↑
Ware JE JrSherbourne CD: The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 30:473–4831992Ware JE Jr Sherbourne CD: The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care 30:473–483 1992
- 86.↑
Weiner BKFraser RDPeterson M: Spinous process osteotomies to facilitate lumbar decompressive surgery. Spine 24:62–661999Weiner BK Fraser RD Peterson M: Spinous process osteotomies to facilitate lumbar decompressive surgery. Spine 24:62–66 1999
- 87.↑
Weiner BKWalker MBrower RSMcCulloch JA: Microdecompression for lumbar spinal canal stenosis. Spine 24:2268–22721999Weiner BK Walker M Brower RS McCulloch JA: Microdecompression for lumbar spinal canal stenosis. Spine 24:2268–2272 1999
- 88.↑
Weinstein MAMcCabe JPCammisa FP Jr: Postoperative spinal wound infection: a review of 2,391 consecutive index procedures. J Spinal Disord 13:422–4262000Weinstein MA McCabe JP Cammisa FP Jr: Postoperative spinal wound infection: a review of 2391 consecutive index procedures. J Spinal Disord 13:422–426 2000
- 89.↑
White AAPanjabi MM: Clinical Biomechanics of the Spineed 2. Philadelphia: JB Lippincott1990White AA Panjabi MM: Clinical Biomechanics of the Spine ed 2. Philadelphia: JB Lippincott 1990
- 90.↑
Wiesinger GFNuhr MQuittan MEbenbichler GWolfl GFialka-Moser V: Cross-cultural adaptation of the Roland-Morris questionnaire for German-speaking patients with low back pain. Spine 24:1099–11031999Wiesinger GF Nuhr M Quittan M Ebenbichler G Wolfl G Fialka-Moser V: Cross-cultural adaptation of the Roland-Morris questionnaire for German-speaking patients with low back pain. Spine 24:1099–1103 1999
- 91.↑
Yamazaki KYoshida SIto TToba TKato SShimamura T: Postoperative outcome of lumbar spinal canal stenosis after fenestration: correlation with changes in intradural and extradural tube on magnetic resonance imaging. J Orthop Surg 10:136–1432002Yamazaki K Yoshida S Ito T Toba T Kato S Shimamura T: Postoperative outcome of lumbar spinal canal stenosis after fenestration: correlation with changes in intradural and extradural tube on magnetic resonance imaging. J Orthop Surg 10:136–143 2002
- 92.↑
Yone KSakou T: Usefulness of Posner's definition of spinal instability for selection of surgical treatment for lumbar spinal stenosis. J Spinal Disord 12:40–441999Yone K Sakou T: Usefulness of Posner's definition of spinal instability for selection of surgical treatment for lumbar spinal stenosis. J Spinal Disord 12:40–44 1999
- 93.↑
Young SVeerapen RO'Laoire SA: Relief of lumbar canal stenosis using multilevel subarticular fenestrations as an alternative to wide laminectomy: preliminary report. Neurosurgery 23:628–6331988Young S Veerapen R O'Laoire SA: Relief of lumbar canal stenosis using multilevel subarticular fenestrations as an alternative to wide laminectomy: preliminary report. Neurosurgery 23:628–633 1988
- 94.↑
Zander TRohlmann AKlockner CBergmann G: Influence of graded facetectomy and laminectomy on spinal biomechanics. Eur Spine J 12:427–4342003Zander T Rohlmann A Klockner C Bergmann G: Influence of graded facetectomy and laminectomy on spinal biomechanics. Eur Spine J 12:427–434 2003
- 95.↑
Zanoli GStromqvist BJonsson BPadua RRomanini E: Pain in low-back pain. Problems in measuring outcomes in musculoskeletal disorders. Acta Orthop Scand Suppl 73:54–572002Zanoli G Stromqvist B Jonsson B Padua R Romanini E: Pain in low-back pain. Problems in measuring outcomes in musculoskeletal disorders. Acta Orthop Scand Suppl 73:54–57 2002
