Accepted Manuscript Minimally Invasive Treatment of Spondylolisthesis H. Louis Harkey, MD PII:

S1878-8750(15)00886-4

DOI:

10.1016/j.wneu.2015.07.020

Reference:

WNEU 3047

To appear in:

World Neurosurgery

Received Date: 6 July 2015 Accepted Date: 8 July 2015

Please cite this article as: Harkey HL, Minimally Invasive Treatment of Spondylolisthesis, World Neurosurgery (2015), doi: 10.1016/j.wneu.2015.07.020. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Title: Minimally Invasive Treatment of Spondylolisthesis Author: H. Louis Harkey, MD

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Affiliation: Department of Neurosurgery University of Mississippi Medical Center 2500 North State Street

Corresponding Author: H. Louis Harkey, MD

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Email: [email protected]

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Jackson, MS 39157

Article Type: PERSPECTIVE statement

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Abbreviations: MISS: Minimally invasive spinal surgery

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Minimally Invasive Treatment of Spondylolisthesis

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Degenerative spondylolisthesis and isthmic spondylolisthesis have a number of features in common. Both are characterized by a vertebral slip that narrows both the central canal and the foramen on either side. Both are associated with instability, in that the slip may

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be visibly dynamic or glacially progressive. In both varieties, the disc plays a role,

offering stability by virtue of strong annular attachments to the adjacent vertebral bodies

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yet contributing to instability through progressive degeneration. As the disc space collapses in unison with progressive slip, the annulus within the foramen may contribute to root compression. The posterior arch plays a role in slip in each type of spondylolisthesis but for different reasons. In degenerative spondylolisthesis, the

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posterior elements maintain a strong bony attachment to the body, but the relative sagittal orientation of the facets and/or facet diastases allow forward slip. In isthmic spondylolisthesis, the posterior elements lack the bony continuity, while a fibrous union

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limits the amount of slip. In both types of spondylolisthesis, thickened ligamentum flavum or fibrous callus may add to the stenosis. Symptoms develop in either variety

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when the stenosis resulting from the bony slip and pathologic soft tissues becomes severe enough to compress the exiting and/or traversing nerve roots. Dysfunctional motion at the slipped segment may produce some mechanical pain as well as additional root compression.

Differences include the fact that degenerative spondylolisthesis is most common at L4/5

ACCEPTED MANUSCRIPT Harkey 3 and isthmic spondylolisthesis is most common at L5/S1. The isthmic variety is seen earlier in life, often becoming symptomatic in the middle decades of life, whereas the degenerative variety presents much later in life. Finally, isthmic spondylolisthesis can

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progress to a high-grade slip, whereas degenerative spondylolisthesis rarely, if ever, progresses beyond a grade II slip.

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Medical evidence supports the role of surgery over non-operative therapies for the

management of lumbar spondylolisthesis regardless of the flavor. The majority of

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evidence used to arrive at this conclusion is based upon surgical procedures involving direct decompression, plus various forms of instrumented fusion that address stability, which in most cases were open procedures. (9)

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Minimally invasive spinal surgery (MISS) is increasing in popularity as techniques and instrumentation are developed to assist in safe, efficient and effective replacements for traditional open spinal procedures. Proponents of MISS tout advantages, such as

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minimizing post-operative pain, shortening recovery, reducing blood loss, limiting soft tissue damage and reducing scar tissue. When MISS is used for spondylolisthes, there is

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less destruction of existing stabilizing structures, particularly the facet, ligaments and muscles contralateral to the side of the decompression. (6)

{Author, et al} present a retrospective study comparing the clinical outcome of patients with degenerative lumbar spondylolisthesis and isthmic spondylolisthesis treated with an identical surgical technique. The surgical technique was minimally invasive employing

ACCEPTED MANUSCRIPT Harkey 4 unilateral, transfacet, interbody fusion and bilateral pedicle screw fixation. This technique offered all the recognized advantages of minimally invasive surgery. Nerve roots were directly decompressed centrally and on both sides from a unilateral exposure,

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a technique that has been well described. (2, 4, 7) Additional indirect decompression of nerve roots was attempted with interbody distraction, reduction and fusion.

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The results were comparable with similar clinical and radiological outcomes. Both

groups had significant postoperative improvement in VAS and ODI scores but there was

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no significant difference between the two groups. Radiological outcomes were similar in both groups as well, with slight restoration in disc height but more significant reductions in the degree of slip. Fusion rates were nearly 90% at one year in both groups.

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It is not surprising that similar outcomes are seen in similar conditions treated exactly the same way. Assuming this study is indeed as well controlled as described, any differences seen between the two groups would, by design, be attributable to the differences in

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pathology that the classification distinguishes. However, their outcome measures assess symptoms that are largely common to both conditions and would not expect to reflect any

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differences in pathology. Nonetheless, the authors achieve their implied purpose by showing that IS is as effectively treated with a minimally invasive technique just as DS.

Symptomatic spondylolisthesis is effectively treated by decompression alone, either open or minimally invasive (1). This raises question of how much value is added by the instrumented interbody fusion over and above the direct decompression alone. A

ACCEPTED MANUSCRIPT Harkey 5 successful fusion could improve pain relief in two ways: immobilization and indirect decompression. Immobilizing a dysfunctional segment may relieve mechanical back pain and it may also relieve lower extremity pain by preventing dynamic root

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compression.

Indirect decompression presumably increases the size of the central canal and the

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foramina through reduction of the slip and additional intervertebral disc height. Any

nerve root decompression by indirect means could result in improved lower extremity

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pain scores. The radiological data suggest that the procedure produces only minimal increase in disc height. The reported 0.79 mm average gain in height is of questionable clinical significance and certainly within measurement error. Therefore, only reduction in slip could have produced any significant indirect decompression. But since all

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patients received both direct and indirect decompression, there is no way to differentiate how much reduction of slip contributed to the improvement in radicular symptoms.

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Unfortunately, the clinical outcome data in this study does not address mechanical back pain as an outcome independent of radiculopathy or neurogenic claudication. Therefore

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no conclusion can be made regarding the benefit with regard to mechanical back pain provided by the surgery.

Robust review of medical literature supports surgery over prolonged medical management of symptomatic stenosis associated with spondylolisthesis. Solid arthrodesis, enhanced through instrumentation, improves outcomes in spondylolisthesis

ACCEPTED MANUSCRIPT Harkey 6 patients but not in stenotic patients without spondylolisthesis. (8, 9) The high quality evidence used to generate these recommendations is based largely upon studies relying on open procedures. To date, there is little, if any, quality evidence comparing minimally

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invasive decompression to minimally invasive decompression plus fusion. Perhaps

minimally invasive direct decompression is the major contributor to symptomatic relief, both neurogenic and mechanical. The interbody fusion and pedicle fixation may simply

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add time, morbidity and cost to the overall procedure without clinically supplementing

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the overall outcome.

Cost analysis literature in this area is limited, complex and even contradictory. (3) But at least one report concludes that for symptomatic spondylolisthesis (leg pain predominant),

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decompression without fusion is more cost effective than instrumented fusion. (5)

As healthcare moves from fee-for-service to value based purchasing, costly procedures will come under increasing scrutiny. Accountable care organizations will want to

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analyze the surgical management of spinal disorders, looking at metrics such as length of stay and readmission rates, in addition to the direct variable cost of instrumentation and

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fusion. It will be incumbent upon the spinal scientific community to establish the relative value of decompression versus stabilization in the management of spinal stenosis.

No one would argue with the recommendation that surgical intervention for acute symptomatic stenosis associated with spondylolisthesis should follow a reasonable period of conservative management. A large proportion of patients will recover spontaneously

ACCEPTED MANUSCRIPT Harkey 7 or as a result of medical therapy. It follows to reason that minimally invasive decompression could serve as the initial surgical management, saving the more

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aggressive and expensive fusion procedure for the outlying failures.

ACCEPTED MANUSCRIPT Harkey 8 References: 1) Alimi M, Hofstetter CP, Pyo SY, Paulo D, Härtl R: Minimally invasive laminectomy for lumbar spinal stenosis in patients with and without preoperative

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spondylolisthesis: clinical outcome and reoperation rates. J Neurosurg Spine 22: 339-352, 2015.

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2) Caspar W, Papavero L, Sayler K, Harkey HL: Precise and limited decompression

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for lumbar spinal stenosis. Acta Neurochir 131:130-136, 1994.

3) Harrop JS, Hilibrand A, Mihalovich KE, Dettori JR, PhD, Chapman J: Costeffectiveness of surgical treatment for degenerative spondylolisthesis and spinal

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stenosis. Spine 39(Suppl):S75-S85, 2014

4) Khoo LT, Fessler RG: Microendoscopic decompressive laminontomy for the

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treatment of lumbar stenosis. Neurosurg 51(Suppl 2):S146-S154, 2002.

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5) Kim S, Hedjri SM, Coyte PC, Rampersaud YR: Cost-utility of lumbar decompression with or without fusion for patients with symptomatic degenerative lumbar spondylolisthesis. The Spine J 12:44–54,2012.

6) Palmer S, Davison L: Minimally invasive surgical treatment of lumbar spinal stenosis: Two-year follow-up in 54 patients. Surg Neurol Int 3:41-47, 2012

ACCEPTED MANUSCRIPT Harkey 9 7) Palmer S, Turner R, Palmer R: Bilateral decompression of lumbar spinal stenosis involving a unilateral approach with microscope and tubular retractor system. J

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Neurosurg (Spine 2) 97:2013-217, 2002.

8) Resnick DK, Watters WC, , Mummaneni PV, Dailey AT, Wang JC, Choudhri TF, Eck J, Sharan A, , Groff MW, Wang JC, Ghogawala Z, Dhall SS, Kaiser MG: Guideline

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update for the performance of fusion procedures for degenerative disease of the

Neurosurg Spine 21:54-61, 2014.

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lumbar spine. Part 10: Lumbar fusion for stenosis without spondylolisthesis. J

9) Resnick DK, Watters WC, Sharan A, Mummaneni PV, Dailey AT, Wang JC, Choudhri TF, Eck J, Ghogawala Z, Groff MW, Dhall SS, Kaiser MG: Guideline update

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for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 9: Lumbar fusion for stenosis with spondylolisthesis. J Neurosurg Spine

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21:62-66, 2014.

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Highlights Title: Minimally Invasive Treatment of Spondylolisthesis

Similarities and differences between degenerative and isthmic spondylolysthesis



Relative contribution of decompression versus fusion in surgical management of spondylolisthesis



Advantages of minimally invasive lumbar decompression techniques.



Conservative management followed by minimally invasive decompression for failures followed by stabilization for failures

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Minimally Invasive Treatment of Spondylolisthesis.

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