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Open lumbar laminectomy: Indications, surgicaltechniques, and outcomes

Steven S. Agabegi, MDn, and Hillary L. McClung, PA-C

University of Cincinnati, 231 Albert Sabin Way, Mail Location 0212, Cincinnati, OH 45267

a b s t r a c t

Lumbar spinal stenosis is the most common in

this article is to review the efficacy of open lam

who fail conservative management. Identificati

with clinical findings supported by imaging) a

ultimate outcomes. Review of current surgical

cates that laminectomy remains a viable treatm

nt matter & 2013 Elsevie1053/j.semss.2013.05.004

thor.agabegis@yahoo.com (S.

dication for lumbar surgery. The objective of

inectomy as a treatment option for patients

on of appropriate surgical candidates (those

nd adequate surgical decompression affect

techniques and documented outcomes indi-

ent option in treating symptomatic stenosis.

& 2013 Elsevier Inc. All rights reserved.

1. Introduction

Spinal stenosis is the most common reason for lumbar surgeryin patients over 65 years of age Deyo et al. (2005).1 Lumbarstenosis may be due to congenital narrowing of the spinalcanal or degenerative changes or both. Degenerative changesthat lead to stenosis include ligamentum flavum hypertrophy,superior facet process hypertrophy or osteophyte formation,disc protrusion, and degenerative spondylolisthesis. Hyper-trophy of the ligamentum flavum and facet joints leads tonarrowing of the lateral recess or nerve root foramen. Aging isassociated with loss of disc height, which also narrows theforamen vertically and if pronounced can allow buckling of theligamentum flavum into the spinal canal. Facet joint hyper-trophy and hypertrophic changes in the soft tissues, osteo-phytes, or disk bulging can all result in narrowing of the spinalcanal, creating the trefoil-shaped narrowing of the canalreferred to as spinal stenosis. Facet degeneration can beassociated with anterior spondylolisthesis that usually affectsL4 and L5 and contributes to narrowing of the foramina.

2. Indications

Surgery is generally considered in patients who have failedat least 8–12 weeks of conservative management with activity

r Inc. All rights reserved.

S. Agabegi).

modification, physical therapy, medications, and/or epiduralsteroid injections. The natural history of symptomatic spinalstenosis is generally favorable with nonoperative treatment.The decision for surgery is dictated by the degree of pain anddisability experienced by the patient, imaging studies, andthe failure of conservative treatment.Central stenosis often presents with neurogenic claudica-

tion but may also present with a unilateral radiculopathy.Lateral recess and foraminal stenosis usually cause unilateralradicular symptoms. Objective weakness is a rare finding andmost patients with spinal stenosis do not present withobjective physical findings, although deficits may be presentafter ambulation.Proper patient selection is critical to achieving a good

outcome. The best candidates for surgery are patients withneurogenic claudication, whose leg symptoms worsen withambulation and spine extension. These patients typicallyhave improvement in their leg symptoms when they sit orlean forward on a shopping cart or a walker. Patients mayhave either unilateral radicular pain or diffuse, nondermato-mal symptoms beginning in the buttocks and extending avariable distance into the legs, depending on area of stenosis.These symptoms are classically worsened by ambulation.Patients with primarily low back pain typically do not have a

good outcome with surgical intervention. Patients with lowback pain and neurogenic claudication should be counseled

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that the purpose of surgery is to relieve their leg symptoms andthat the low back pain may not improve after surgery. Gen-erally patients who have a significant component of low backpain preoperatively continue to have back pain after surgery.The relief of pain after epidural steroid injections may be

a good prognostic indicator of surgical outcome. Derby et al.2

found that patients who experienced more than 50% improve-ment in leg pain for at least a week after the injection also hadgreater than 50% improvement in leg pain after surgery. Con-versely, patients who did not improve after injection had apoor surgical outcome.2

Lumbar laminectomy without fusion is indicated in patientswith spinal stenosis without instability. All patients shouldhave standing anteroposterior (AP), lateral, and flexion/exten-sion radiographs of the lumbar spine to rule out instabilityat the stenotic segment(s). A concomitant fusion should beconsidered for patients with degenerative spondylolisthesis,degenerative scoliosis, or lateral listhesis. Patients with degen-erative scoliosis who require multilevel laminectomies shouldhave fusion performed to prevent worsening of the scoliosis inthe postoperative period (Fig. 1).There are a variety of decompressive techniques available

to address the various pathologies. Decompression maybe limited to a single-level unilateral laminotomy or mayinvolve multilevel bilateral laminectomy with bilateral fora-minotomies. Pre-operative imaging should demonstrate clearevidence of neural compression that is congruent with thepatient's symptoms. All spinal levels that appear to correlatewith the patient's symptoms should be decompressed. Thereremains controversy over whether to decompress levels thatappear to be stenotic but do not seem to correlate with the

Fig. 1 – A 78-year-old female had degenerative scoliosis andunderwent multilevel laminectomies (L1–L4) without fusion.At 6 months postoperation, she developed progression ofthe scoliosis. Although she had a good initial clinical resultwith relief of her neurogenic claudication, a concomitantin-situ fusion is indicated to prevent curve progression.

patient's symptoms. The risk of decompressing an apparentlyasymptomatic level and causing new symptoms from com-plications must be weighed against the possible risk offurther degeneration. Asymptomatic stenotic levels maybecome symptomatic over time. Inadequate decompressionmay result in long-term deterioration in clinical outcomefollowing initially successful surgery, and may be a cause offailed back surgery and/or may necessitate additional spinalprocedures.

3. Surgical technique

The patient is typically positioned on a Jackson table with theabdomen free, to reduce venous compression and intraoper-ative epidural bleeding. Some surgeons prefer to extend thehips to recreate the upright standing posture. This placesmore compression on the neural elements and allows betterassessment of the degree of decompression, ensuring thepatency of the spinal canal and course of the nerve rootsthrough the lateral recesses and into the foramina, followingdecompression. Exposure is performed in standard fashionusing either electrocautery or Cobb elevators. Care is takennot to violate the facet joint capsules if a fusion is not beingperformed. During exposure, it is helpful to identify thelateral edge of the pars interarticularis of each level that isbeing decompressed. Good exposure of the pars allows thesurgeon to assess the width of decompression and helpsavoid excessive thinning of the pars, which may lead tofracture postoperatively. This is particularly relevant in eld-erly patients with osteoporotic bone who may be moresusceptible to pars fracture postoperatively.After exposure is performed and the proper level is iden-

tified with intraoperative radiographs, the interspinous liga-ment is removed from the most inferior to the most superiorspinous processes using a Leksell rongeur. The decompres-sion typically proceeds from a caudal to cranial direction. Thebase of the spinous process and superficial lamina can bethinned with a Leksell rongeur. The interval between thelamina and the ligamentum flavum is identified with anangled curette to allow insertion of a Kerrison rongeur. Thelamina can then be removed with a Kerrison rongeur. Alter-natively, a high-speed burr can be used to perform thelaminectomy as the underlying ligamentum flavum servesas a protective barrier between the dural sac and the burr.If using a burr, care must be taken towards the cephalad halfof the lamina as this region is not protected by ligamentumflavum, which attaches about halfway up on the ventralsurface of the cephalad lamina. Once the lamina has beenremoved, a Woodson elevator can be used to develop theplane between the ligamentum flavum and the dural sac. Theligamentum can then be removed piecemeal with a pituitaryor Kerrison rongeur. One must take great care to ensure thatthere are no adhesions between the ligament and the dura toprevent dural tears. In the presence of severe stenosis or asynovial cyst, gentle dissection is needed to free any adhe-sions before removing the ligament.There are three regions that require sequential attention

when performing decompression: the central canal, thelateral recesses, and the neural foramina. When a

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laminectomy is initiated, the central canal is the first regionto be decompressed. The lateral recess is defined as theregion between the medial edge of the pedicle and the lateraledge of the dural sac (Fig. 2). The lateral recess also extendsinto the disc space level. Partial medial facetectomy isperformed with a Kerrison rongeur. The medial aspect ofthe inferior articular process is removed, which exposes theunderlying superior articular process. This is continued out tothe level of the pedicle. Once the lateral recess has beendecompressed, a Kerrison rongeur is used, following thepedicle out into the foramen, undercutting the superiorarticular process in order to decompress the exiting nerveroot, thus performing foraminal decompression. For example,if performing an L4–5 laminectomy, to adequately decom-press the L4 exiting nerve root in the foramen, the L4 pedicle

Fig. 2 – The lateral recess is the region between the medialedge of the pedicle and the lateral edge of the dural sac. Inthe upper lumbar spine (A), the lateral recess is a narrowerspace than at L4–5 and L5–S1 (B). The pedicles are positionedmore laterally in the lower lumbar spine, which increasesthe dimensions of the lateral recess.

is identified and followed out into the foramen with theKerrison rongeur. To obtain more complete decompression ofthe foramen, foraminal Kerrison rongeurs are available,which have a curved tip that allow more effective under-cutting of the pars and superior articular process. It is moredifficult to decompress the foramina in the upper lumbarspine without resecting the facet joint because the lateraledge of the pedicle (which defines the lateral border of theforamen) is positioned lateral relative to the facet joints. Inthe lower lumbar spine, not as much of the facet needs to beresected to decompress the exiting nerve root (Fig. 3).Care is taken not to remove more than 50% of the facet

joint to avoid iatrogenic instability. If more than 50% of bothfacets is removed, or if one facet is completely removed,fusion may be indicated. The presence of advanced age,marked disc space narrowing, and osteophytes is thought toreduce the need for fusion because of the additional stabili-zing effects these findings produce on the motion segment.In contrast, younger patients with a tall disc may develop anunstable spine when aggressive facet resection is done.A surgeon's intraoperative ability to evaluate the percent-

age of facet joint removed is likely to be highly variable. Thelevel that is being decompressed is also relevant. Due tochange in facet orientation in the lumbar spine, removal of

Fig. 3 – The lateral border of the cephalad pedicle (white line)defines the lateral border of the neural foramen. In the upperlumbar spine (A), this line lies well lateral to the facet joint,making it difficult to adequately decompress the neuralforamen without resecting the facet joint. In the lowerlumbar spine, this line lies more medially and not as muchof the facet needs to be resected to decompress the foramen(B and C).

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a small portion of the medial joint at L1–2 may lead toexcision of the entire inferior articular process. This is moredestabilizing than removing a similar portion of the L4–5 orL5–S1 facet joint (Fig. 4).

4. Outcomes

The outcome after decompressive laminectomy is generallyvery favorable. Several studies have compared surgery with

Fig. 4 – The orientation of the facet joints at L1–2 (A) is moresagittally oriented compared with the more coronallyoriented facets in the lower lumbar spine (B). Removing asimilar amount of bone from both levels would result inmore instability in the upper lumbar spine due to thisdifference in facet orientation.

nonoperative treatment, documenting the benefits of surgeryfor this common condition. Katz et al. prospectively reviewed194 patients who had decompressive laminectomy and found78% were satisfied with the outcome at 6-month follow-up.3

At 7–10-year follow-up of the same cohort, 23% of patientshad undergone reoperation and 75% were satisfied with theresults of surgery.4

Atlas et al.5 in a series of nonrandomized prospectivestudies, compared surgical versus nonsurgical outcome in acohort of 148 patients with symptomatic lumbar stenosis thatwere followed up for 10 years. Eighty-one patients underwentlaminectomy while 67 had nonoperative management. Bothgroups were assessed at 1, 4, 8, and 10 years followingtreatment. At the 1-year follow-up, 55% of surgically versus28% of nonsurgically treated patients reported definiteimprovement in their symptoms. At the 4-year follow-up,70% of surgically treated patients and 52% of nonsurgicallytreated patients reported that their symptoms were better.6

At 8- to 10-year follow-up, leg or back pain was improved in42% of nonoperative group and 54% of operative group. Withlonger-term follow-up, the differences between the twogroups became less significant.There have only been two randomized prospective studies

evaluating the efficacy of surgical versus nonoperative treat-ment for lumbar stenosis. Malmivaara et al. randomized94 patients with spinal stenosis to surgery (50 patients) ornonoperative (44 patients) treatment.7 Patients in both groupsimproved over the 2-year follow-up period, but the surgicalgroup reported greater improvement in leg pain, back pain,and overall disability. Outcomes of surgery remained favor-able at 2 years.7 Interestingly, walking capacity did not differbetween the two groups. Crossover rate was 9% in the non-operative group and 8% in the surgical group.In 2008, the 2-year outcomes of the Spine Patient Outcomes

Research Trial (SPORT) evaluating laminectomy versus con-servative treatment for lumbar stenosis were reported.8 Thiswas a prospective ,randomized, multicenter trial in patientswith spinal stenosis without spondylolisthesis who hadsymptoms for at least 12 weeks and had failed nonsurgicaltreatment.Despite the high incidence of crossover in this trial, the

intention-to-treat analysis showed a significant treatmenteffect favoring surgery on the SF-36 scale for bodily pain;however, there was no significant difference in scores onphysical function or on the Oswestry Disability Index (ODI).The as-treated analysis showed a significant advantage forsurgery at 3 months for all primary outcomes including theSF-36 and ODI. At the 2-year follow-up, on the basis of the as-treated analysis, 63% of patients treated surgically ratedthemselves as having major improvement with their con-dition versus 29% in the nonsurgical group. These differencesremained significant at 4 years.9

5. Summary

Open lumbar laminectomy remains a very successful inter-vention for patients with symptomatic spinal stenosis.Patients with neurogenic claudication, without significantlow back pain, benefit the most from this surgery if they

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have failed conservative treatment options. Recent random-ized controlled trials have shown significant improvement inclinical outcomes with surgery that has been maintained at4 years of follow-up.

r e f e r e n c e s

1 Deyo RA, Gray DT, Kreuter W, et al. United States trends inlumbar fusion surgery for degenerative conditions. Spine.2005;30:1441–1445.

2 Derby R, Kine G, Saal JA, et al. Response to steroid and durationof radicular pain as predictors of surgical outcome. Spine.1992;17:S176–S183.

3 Katz JN, Lipson SJ, Brick GW, et al. Clinical correlates of patientsatisfaction after laminectomy for degenerative lumbar spinalstenosis. Spine. 1995;20:1155–1160.

4 Katz JN, Lipson SJ, Chang LC, et al. Seven- to 10-year outcome ofdecompressive surgery for degenerative lumbar spinal steno-sis. Spine. 1996;21:92–98.

5 Atlas SJ, Deyo RA, Keller RB, et al. The Maine lumbar spine study,part III. 1-year outcomes of surgical and nonsurgical manage-ment of lumbar spinal stenosis. Spine. 1996;21:1787–1794.

6 Atlas SJ, Keller RB, Robson D, et al. Surgical and nonsurgicalmanagement of lumbar spinal stenosis: four-year outcomesfrom the Maine lumbar spine study. Spine. 2000;25:556–562.

7 Malmivaara A, Slatis P, Heliovaara M, et al. Surgical or non-operative treatment for lumbar spinal stenosis? A randomizedcontrolled trial. Spine. 2007;32:1–8.

8 Weinstein JN, Tosteson TD, Lurie JD, et al. Surgical versusnonsurgical therapy for lumbar spinal stenosis. N Engl J Med.2008;358:794–810.

9 Weinstein JN, Tosteson TD, Lurie JD, et al. Surgical versusnonoperative treatment for lumbar spinal stenosis four-yearresults of the spine patient outcomes research trial. Spine (PhilaPa 1976). 2010;35(14):1329–1338.