® Thieme
`
`Exhibit 1038
`LIFE SPINE,INC.
`IPR2022-01602
`
`Surgical Managementof Low Back Pain
`
`SecondEdition
`
`
`
`American
`Association of
`Neurological
`Surgeons
`and the American Association of Neurosurgeons
`American Association of Neurosurgeons ¢ Rolling Meadows, Illinois
`
`000001
`
`Exhibit 1038
`LIFE SPINE, INC.
`IPR2022-01602
`
`000001
`
`

`

`Surgical Managementof Low BackPain
`
`Second Edition
`
`Daniel K. Resnick, MD
`Associate Professor
`Vice Chairman
`Departmentof Neurological Surgery
`University of Wisconsin School of Medicine and Public Health
`University of Wisconsin Hospital and Clinics
`Madison, Wisconsin
`
`Regis W. Haid Jr., MD
`Neurosurgeon and Founding Partner
`Atlanta Brain and Spine Care
`Atlanta, Georgia
`
`Jeffrey C. Wang, MD
`Professor
`Departments of Orthopaedic Surgery and Neurosurgery
`David Geffen School of Medicine
`University of California-Los Angeles
`Chief, Orthopaedic Spine Service
`University of California-Los Angeles Comprehensive Spine Center
`Los Angeles, California
`
`Thieme
`New York ¢ Stuttgart
`
`American Association of Neurosurgeons
`Rolling Meadows, Illinois
`
`000002
`
`
`
`000002
`
`

`

`American Association ofNeurosurgeons (AANS)*
`“hieme Medical Publishers, Inc.
`5550 Meadowbrook Drive
`333 Seventh Ave.
`Rolling Meadows,Illinois 60008-3852
`Yew York, NY 10001
`‘The abbreviationAANSrefers to both the AmericanAssociation ofNeurological Surgeons and theAmericanAssociation ofNeurosurgeons.
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`Library of Congress Cataloging-in-Publication Data
`Surgical management oflow backpain / [edited by] Daniel K. Resnick, Regis W.Haid,Jeffrey C. Wang.—2nded.
`p.;cm.
`Includes bibliographical references and index.
`ISBN 978-1-60406-035-5 (alk. paper)
`1. Backache—Surgery.I. Resnick, DanielK. Il. Haid, Regis W.II. Wang,Jeffrey C.
`[DNLM:1. Low BackPain—surgery. WE 755 $961 2008]
`RD771.B2178874 2008
`617.5'64059-dce22
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`2008018145
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`:1A
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`Copyright © 2009 by Thieme Medical Publishers, Inc., and the American Association of Neurosurgeons (AANS). This book, including
`all parts thereof,
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`

`

`) Anterior Lumbar Interbody Fusion
`
`Rick C. Sasso, A. Kirk Reichard, and Shenil Shah
`
`
`
`
`
`
`
`e g Historical Background
`Es Anterior lumbar interbody fusion (ALIF) wasfirst used
`jn the treatmentof tuberculosis and lumbar spondylolis-
`thesis’? Although described by Capener* in 1932 as the
`» “ideal” operation for spondylolisthesis, he further elab-
` orated that “the technical difficulties of such procedure,
`however, precludetheir trial.” This statement was soon to
`be proven wrong by numeroustechnical advancesin ALIF.
`Wheninitially developed, the transperitoneal approachfor
`lumbararthrodesis was the norm,but waslater replaced
`_ by the retroperitoneal approach. Thefirst description of
`the transperitoneal approach was published in 1906 by
`Muller,> and Iwahara® first reported the later approach
`in 1944, Further broadening the scope of ALIF, Lane and
`Moore’ in 1948 reported ALIF as a treatment for lumbar
`degenerative disk disease. Here they used the transperi-
`toneal approachwith an allogenic bonegraft in 97 patients,
`reporting a 54% fusion rate after 8 months anda clinical
`success rate of 94%,
`Further developing lwahara’s retroperitoneal approach,
`Hodgson and Stock®° established the foundation for the
`modernera of ALIF while treating Pott disease with differ-
`ent bone grafting materials. Debridement of the necrotic
`tissue, followed by decompression of the spinal canal,
`allowed them to place corticocancellous blocks of auto-
`genous bone into the defect to obtain arthrodesis. The
`dowel technique, developed by Ralph Cloward in 1953,
`involved the use of cylindrical shaped corticocancellous
`dowels. Although Cloward'®-'* used a posterior approach,
`his methods for disk removal, end-plate preparation, and
`grafting were widely used. Following Cloward’s dowel
`technique, four individuals adapted this to make their
`owninnovations in bone grafting methods. Two of them,
`Harmon'3 in 1963 and Sacks'4 in 1965, werethefirst to
`utilize the dowel technique for an anterior lumbar fu-
`sion. The third, Crock, developed a cylindrical allograft
`for the anterior approach to the lumbar spine. Finally,
`the fourth, O’Brien et al,’> modified a technique of us-
`ing trapezoidal bone blocks for the treatment of lumbar
`discogenic pain through ALIF. They later developed a hy-
`brid interbody graft using a biologic fusion cage (femoral
`Cortical allograft ring) packed with autogenous cancel-
`lous bonegraft. By using autogenousiliac crest bone graft,
`tapid incorporation and vascularization of the graft are
`achieved, as well as long-term stability.'® Furthermore,
`the femoral allograft ring allows for acute stability of
`
`the construct and a compatible framework for host bone
`ingrowth."5
`Despite the success in safely exposing the anterior lum-
`bar spine, in the 1970s and 1980s stand-alone ALIF was not
`a reliable procedure due to low fusion rates. Early in the de-
`velopmentof the procedure, there was great discrepancy
`among success rates. The reported numbers wereincred-
`ibly inconsistent, with some reporting huge success and
`others complete failure. For example, Lane and Moore,’ as
`stated previously, reported a 94% clinical success rate. In
`contrast, though, Adkins!” in 1955 had a fusion rate of 1%.
`Early reports encompassing numeroussurgical techniques
`and a heterogeneous group of patients demonstrateda fu-
`sion rate of 95% by Harmon, 70% by Hoover,'® 90% by
`Crock,'? and 96% by Fujimakietal.2° However, other reports
`cited fusion rates of 19%, 40%, 45%, and 56% by Calandruc-
`cio and Benton,?! Nisbet and James,” Raney and Adams,?3
`and Flynn and Hoque,” respectively. A 1972 study con-
`ducted from the MayoClinic and authored by Stauffer and
`Conventry”’ concluded definitively that the stand-alone
`ALIF had a low success rate. After reporting on 83 pa-
`tients who underwent ALIF without instrumentation be-
`tween 1959 and 1967, they found an extremely low success
`rate, with pseudarthrosis occurring in 44%. The MayoClinic
`study resulted in a review of the ALIF as a stand-alonepro-
`cedure, andit soon afterfell out of favor, particularly for the
`indication of lumbar degenerative disk disease and lumbar
`axial back pain.
`In response to these low fusion rates, a technique
`combining an ALIF with posterior fusion became very
`common.”° Althoughthe anterior approach continued to be
`utilized for the diskectomy,lordosis restoration, and fusion
`block insertion, a posterior approach was used to access
`the posterior elements for instrumentation and stabiliza-
`tion (Fig. 10.1). The addition of posterior instrumentation
`increases stability across the segment and decreases mo-
`tion while the fusionsolidifies. Despite having a very high
`fusion rate, the magnitude of the circumferential fusion
`increased morbidity. Although the ALIF usage had been re-
`vitalized with posterior instrumentation, the searchfor a
`better construct continued,
`These new innovations included anterior lumbar instru-
`mentation, first reported by Humphries et al*’ in 1961.
`They developed a slotted, contoured plate that was placed
`over the anterior lumbarspine in an attempt to enhance
`arthrodesis. Another advancein anterior hardware wasthe
`cylindrical cage. The first cylindrical cages were modified
`from a smooth,stainless steel, fenestrated cylinder (Bagby
`
`000004
`
`000004
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`

`

`38
`
`Fig. 10.1 Lateral radiograph of circumferential fusion using a
`femoralring allograft forthe anterior lumbarinterbodyfusion (ALIF)
`and translaminar facet screwsfor posteriorstability.
`
`basket) used by Bagby and colleagues in the mid-1970s and
`early 1980s to treat Wobbler syndrome, whichis a chronic
`cervical instability causing myelopathy in thoroughbred
`horses.28 In Bagby’s procedure, he packed the cage with
`cancellous bone chips obtained from the reaming of the
`cervical decompression, thus eliminating the need for an
`autograft harvest. Further, the cage was developed with
`perforationsin its walls to allow for bone ingrowth and to
`enhance fusion. This construct allowedforearly stability
`and improved arthrodesis. Animals studies corroborated
`the success of this procedure with fusion rates as high as
`88%.28-31 Following the originalcylindrical cage, more and
`more improvements in the design of the cages led to the
`Bagby and Kuslich design (BAK, Spine-Tech, Minneapolis,
`MN), whichwasfirst implanted in humansin 1992? This
`BAKtitaniumcage wasthreaded and screwed into the end
`plates for stabilization and fusion of the segment. Another
`similar device developed by Ray®? (Ray TFC, Surgical Dy-
`namics, Norwalk, CT) wasinitially used in posterior lumbar
`interbody fusion (PLIF) but waslater adapted to the ALIFs
`as well.
`Although cylindrical cages wereoriginally metalalloy,
`the development of machined bone dowels provided sev-
`eral advantages. Threaded bone dowels are similar in na-
`ture to a metal cage, but differ in that they are osteocon-
`ductive, incorporated over time, radiographically benign,
`and easier to revise.
`Despite the rampant usage and initial success of the
`threaded cylindrical cage in the late 1990s, the next gen-
`eration, the lumbar tapered (LT) cage, has several advan-
`tages overthe cylindrical predecessor.It provides the same
`benefits of a cylindrical device, but allows the surgeon to
`symmetrically ream the end plate while restoring lordosis.
`Symmetric reaming prepares the end plate for fusion and
`preserves the strength.
`
`
`
`Fig. 10.2 Lateral radiograph of circumferential fusion using 4—
`femoralring allograft for the ALIF and pedicle screws and rods for
`
`posteriorstability.
`
`f
`In addition, LT cages packed with recombinant human
`
`bone morphogenetic protein (rhBMP-2) perform aswell ag”
`
`those packed with autograft.
`Other constructs include trapezoidal cages. Trapezoidal a
`
`constructs can be made from various materials, but several 7 it ally s
`features are shared, including a large footprint for maxi- 7
`eh at the
`
`mum end-plate coverage and a large inner volumefor bone —
` infrec
`Be
`graft and future fusion maturation.
`lize t
`Although cages continueto be widely used, femoralring
`) end |
`
`allografts (FRAs), as well as other trapezoidal implants are7 a, imple
`te gene!
`growing in popularity. The rhBMP-2 is also commonly used
`duringall spinal fusions. Using rhBMP-2 decreases donor- " _ verte
`
`site morbidity, as well as operating room time, and has —
`ee
`ther
`et
`proven to be as effective as autologous bone. Not sur-
`cessi
`
`prisingly, the surgical approach has again beenrevisited, © body
`and recent research has shied away from laparoscopic ap- 4
`i ;
`by c
`proaches in favor of a retroperitoneal “mini” open ap- — ar footy
`
`proach. Although the ALIF was conceived over 100 years 9§tion
`ago, it continues to be updated and improved with each 7f
`(Fig.
`new generation ofimplantand surgeon.
`fay
`St
`
`The ALIF has developed over decades, and specific at- |
`pee ical
`tributes have been identified as primary contributors to a ;
`vidii
`
`successful outcome. With thediskas the pain generator, re-
`tive
`movalof the pain source witha total diskectomy addresses ‘
`and
`the patient's presenting complaint.Also, restoration ofdisk 7
`tribt
`height can alleviate foraminal stenosis. Re-creation of na-
`viro
`tive lordosis may decrease juxtalevel stress. And lastly, 9 nou
`posterior stabilization maximizes the likelihood of fusion |
`late
`(Fig. 10.2).
`virocific
`ee sior
`m@ Biomechanics
`van
`The greatest strength of the vertebral body is present in
`=
`the peripheral subchondralboneof the cortical endplate.
`000005
`
`
`
`000005
`
`

`

`- when threaded cages are used, the preparation process
`" yiolates this peripheral ring of subchondralbone. Although
`this process compromisesthe strong ring of subchondral
`- pone and theoretically raises the risk of subsidence,it
`also exposes vascular cancellous bone that may facilitate
`healing.
`Incontrast, to prepare the intervertebral space for a non-
`threaded, trapezoidal implant, such as an FRA, the strong
`ir peripheralring of subchondral boneis preserved and di-
`- rectly supports the graft while fusion occurs. In the past
`_ when FRAs were fashioned by the surgeon on the back
`table, the size and shape weredifficult to match, and this
`-
`HS strong ring of subchondral bone may not have been max-
` jmally utilized. Now, FRAs are more frequently manufac-
`tured, and thus size and shape are more predictable.This
`enables the surgeon to match the implant to the patient
`and build the most stable construct. In addition, manufac-
`tured FRAs have the benefit of insertion instruments that
`distract the adjacent vertebral bodies and ensure proper
`alignmentand placement.
`The spine enduresa wide range of biomechanicalforces,
`from 400 N while standing, to greater than 7000 N during
`heavy lifting,?475 with an maximum compression strength
`of 10,000 N.*® The selected implant should notfail un-
`der these loads. When tested, modern-day implants usu-
`ally sustain the maximum loads, with failure occurring
`at the end plate or the sacroiliac joint.2”? With implants
`infrequently failing, every effort must be madeto uti-
`lize the intrinsic strength and healing potential of the
`end plate to promote rapid fusion. Considering that the
`implants usually do not fail, when constructs do fail, it
`generally results in subsidence of the implant into the
`vertebral body, or cavitation. As the end plate fails, ei-
`ther due to violation during preparation or after ex-
`cessive loading, the implant migrates into the vertebral
`body and the segmentcollapses. Cavitation is addressed
`by choosing an implant with a large contact area, or
`footprint. A larger footprint provides a bigger founda-
`tion for the implant, decreasing the load per square inch
`(Fig. 10.3).
`Subsequently, a successful implant should be mechan-
`ically strong to withstand compressive loads while pro-
`Viding an osteogenic, osteoinductive, and osteoconduc-
`tive matrix. Many metal alloy implants provide strength
`and stability but are unable to incorporate these otherat-
`tributes. To compensate, metal implants provide an en-
`vironment that allows the surgeon to place an autoge-
`nous cancellous bone graft, which does accomplish these
`later goals. Although metal implants can provide an en-
`Vironmentthatis fusion friendly,it is limited by the spe-
`cific design and subsequent volumeavailable for the fu-
`sion to traverse through the implant. To maximize the area
`available for fusion, the surgeon should exposethe entire
`end plate with a total diskectomy,?* as well as choose an
`implant that provides the most volume for the biologic
`substrate and future fusion block.
`
`89
`
`10 Anterior Lumbar interbody Fusion
`
`
`
`Fig. 10.3 Sagittal reconstruction of a computed tomography(CT)
`scan with a femoral allograft at L5-S1 demonstratinga large foot-
`print and supporton the peripheral endplate.
`
`Implant design affects how the loadis transmitted to the
`adjacent vertebra and may contribute to juxtalevel disco-
`genic pain.*° A recent biomechanicalanalysis revealed that
`greater implant contact area transmits loads to the adjacent
`segmentin a more physiologic manner and could decrease
`adjacentlevel pain, as Kumaret al*? found in 2005 that im-
`plants with smaller surface areas transmit loads in a sim-
`ilar manner to a degenerative disk that causes discogenic
`pain. In addition, physiologic stress patterns are better re-
`created whenthepatient’s lordotic curve is restored. Con-
`sequently, when choosing a device,the largest appropriate
`implant should be carefully implanted after a total diskec-
`tomy. This would theoretically prepare the end plate in the
`correct fashion, load the adjacent vertebra more physio-
`logically, and, when fused, minimize the risk of juxtalevel
`disease and pain.
`Rh-BMP-2 is now routinely used for spinal fusions. The
`decrease in donor-site morbidity and operating room (OR)
`time are inviting; however, a recent study found a con-
`cerning trend. This prospective cohort study found a lower
`fusion rate with rhBMPin FRAs. Although,the ALIFs studied
`were stand-alone, the fusion rate was decreased with the
`use of rhBMP. The authors believe that the drop in fusion
`rate, although insignificant, may be secondary to rhBMP-
`induced resorption of the FRA (Fig. 10.4). If the ring is ab-
`sorbed more quickly, the graft may weaken or fragment,
`whichallows motion at the segment before fusion occurs,
`resulting in an unsatisfactory outcome.” This stand-alone
`study reinforces the significance of stabilizing the fusion
`segment. Although FRA implants are stable at the time of
`implantation, rhBMP may accelerate the resorption pro-
`cess and destabilize the segment before fusion can occur.
`Posterior stabilization with pedicle screwsor translaminar
`facet screws provides the needed stability necessary for
`fusion.
`
`000006
`
`000006
`
`

`

`
`
`
`physiologic lordosis, eliminating motion across the seg. 7
`ment, and most importantly, achieving a stable fusion.
`
`w Patient Selection
`
`a
`
`Most low back pain is transient and self-limiting; how-
`
`ever, 5% does not respond to nonoperative treatment.
`I
`Although this small percentage of patients does not im- "
`
`prove with the most conservative measures, the surgeon ,
`must be confident thatall conventional alternatives have
`
`been exhausted. Leaving options behind and movingahead q
`too quickly places risks on patients who would have im-—
`proved without surgery and puts the surgeon at risk of an
`
`unacceptable outcome.Utilizing conservative methods and —
`screening tests with high predictive value improves prac- 7
`"Fig.10.5 Lateral
`tice outcomes.
`
`t ically abnormal L
`The ALIF is a commonlyused surgical intervention to
`
`
`treat discogenic low back pain not controlled by nonop- 7)
`—
`a:
`erative measures. Indications for an interbody fusion in-
`clude degenerative disk disease ofone or two adjacentlev- 7}‘Another pr
`els ofthe lumbarspine, with severe, chronic, disabling, low ~~}selective nerv
`backpainlastinglongerthan6monthsandunresponsiveto by.
`the pathophys
`=Aeois
`complex disk
`adequate nonoperative therapy.3347 Less than three levels
`=.
`positive resu’
`should be addressed at a time because the risk of pseu-
`—
`symptomsfol
`darthrosis increases with each additional level fused and
`Pani
`with the bene
`clinical success decreases.**-°°
`of simply dec
`The pathophysiology of discogenic pain is poorly un-
`cedure is eas!
`derstood; however, we do know that other factors, such
`ogist and giv
`as compensation and pendinglitigation, affect outcomes.”
`before surgic
`These confounding variables must be accounted for prior
`Operative
`to determination ofthe definitive therapy. The importance
`patientat ris
`of the history and physical examination cannot be over-
`patient outc
`stated; the interaction with the patient is an opportu-
`tion. The lea
`nity for the surgeon to assess the patient's expectations
`are the histc
`and determine if the patient is motivated by secondary
`gain.Magnetic resonance imaging (MRI) is a sensitive and
`specific tool for diagnosing disk pathology; however,
`asymptomatic disk pathology or herniation can be as high
`as 34%} Boden et al®? studied 20- to 39-year-olds, and
`found that more than one third had asymptomatic disk de-
`generation and more than one fifth had asymptomatic disk
`herniations. MRI should not be usedasa screening tool and
`should be ordered only when clinical suspicionis high for
`spinal pathology.
`Although controversial, diskography can provide the
`surgeon additional information prior to surgical interven-
`tion. Diskography is a diagnostic tool that many feel corre-
`lates pathoanatomy and symptomatology in patients with
`primary discogenic pain. Several studies suggest improved
`outcomesin interbody fusion patients after supportive pre-
`operative diskography.**** Re-creation ofconcordant pain
`with diskography especially under low pressures can ver-
`ify the pain source or help rule out pathology at 4 specific
`level (Fig. 10.5). -- ~.
`000007
`
`
`
`Fig. 10.6 /
`injection (¢
`
`ical Management of Low Back Pain
`
`j. 10.4 Sagittal reconstruction of CT scan with a femoralallo-
`aft packed with recombinant human bone morphogenetic pro-
`in (rhBMP-2)demonstrating early resorptionofboneatthe caudal
`aft—host junction.
`
`Although the ALIF was conceived as a stand-alone de-
`ice, posterior instrumentation has proven to be optimal
`yr reliable fusion. Even though the stand-alone ALIF does
`ave intrinsic stability, posterior stabilization is recom-
`yended because posterior instrumentation providessta-
`ility in the range the cage does not.’ Several implant
`iptions have been used, two of which are pedicle screws
`nd translaminar facet screws. Ferrara et al42 performed
`| biomechanical comparison of these two constructs and
`oundboth to be reliable constructs, with similar proper-
`jes. After 180,000 cycles, both constructs were equivalent
`vith regardto stiffness and motion. With similar biome-
`-hanical properties, implant choice can be determined by
`ther factors, including surgeon preference, and patient-
`specific characteristics.
`Although both constructs have similar integrity, multi-
`ple factors should be considered. Best and Sasso*? recently
`reviewed 105 ALIF patients receiving translaminar screws
`or pedicle screws, and they found that the OR time was
`greatly reduced with translaminar screws, and the blood
`loss wassignificantly less. Translaminarscrew placement
`combinesa midline incision and percutaneousscrew place-
`ment, thus decreasing the overall incision length. To place
`translaminar facet screws,less muscle stripping is required,
`the cephaladfacet joint is not disrupted, and instrumenta-
`tion prominenceis not an issue.*4 Despite the benefits of
`translaminar facet screws, patients with a prior complete
`laminectomy and removalof the spinous process or those
`with spondylolysis are not candidates.
`Understanding the biomechanics of the spineiscritical
`to interpreting the principles with thelatest implants and
`techniques. Despite the ever-changing approach to lumbar
`disk disease, the ALIF relies on removal of the entire de-
`generative disk, preserving end-plate strength,re-creating
`
`
`
`
`
`
`
`000007
`
`

`

`
`
`
`
`
`Fig. 10.6 Anteroposterior radiograph during selective nerve root
`Injection (SNRI) of the left $1 nerve.
`
`hers]
`a
`
`Fig. 10.5 Lateral radiograph during diskography with a morpholog-
`‘cally abnormal L5-S1 disk and a normal L4-L5 disk.
`
`Another provocative test with predictive value is the
`i selective nerve root injection (SNRI), which can elucidate
`_
`the pathophysiology of the pain generatorin patients with
`complex disk disease or nontraditional radiculopathy. A
`positive result, meaning the patient has 100% relief of
`symptoms following the injection of anesthetic, correlates
`with the benefits achieved following surgical intervention
`of simply decompressing the offending nerve.>” This pro-
`cedure is easily performed by an experienced anesthesiol-
`ogist and gives the surgeon an added layer of confidence
`before surgical intervention (Fig. 10.6).
`Operative intervention for spinal pathology places the
`_ patientat risk. Utilizing available diagnostic tools improves
`_ patient outcome and avoids low-yield surgical interven-
`tion, The least expensive and mosteasily used toolslikely
`are the history and physical examination of the patient.
`
`10 Anterior Lumbar Interbody Fusion
`
`
`91
`
`@ Clinical Studies
`
`The ALIF has evolved over several decades through constant
`reevaluation and technique revision. To date, the most re-
`liable constructs employ an anterior fusion that is stabi-
`lized posteriorly with instrumentation. Several attempts
`have been madeto optimize an anterior-only, stand-alone
`technique; however, fusion rates have beenlessreliable.
`Posterior instrumentation provides the additional stabil-
`ity needed for rapid fusion, and now with the addition of
`rh-BMP, donor-site morbidity can be eliminated.
`Despite the wide usageofcylindrical cages throughout
`the 1990s, no prospective fusion data was available un-
`til 2004. Starting in 2000, 140 patients were enrolled in a
`prospective, randomized, controlled, clinical trial compar-
`ing fusion rates of stand-alone threaded cages and stand-
`alone FRAs.*® The 13 surgeons whotookpart in the trial
`implanted either a pair of cylindrical threaded titanium
`cages or an FRA. Both implants were packed with autograft,
`and fusion was evaluated at 6-monthintervals by a board-
`certified radiologist. At6 months, 95% ofthe threaded cages
`were fused as compared with only 10.9% of the FRAs, and
`the superior fusion rate remainedin favorofthreaded cages
`throughout the study. The highest fusion rate obtained
`by the FRA control group was 51.9% at 2 years, in contrast
`to the lowest fusion rate seen with the threaded cages was
`95% at 6 months. Regardless of the outstanding fusion ca-
`pacity of threaded cages, clinical outcomes remained equal
`betweengroups.” Thesesurprising clinical findings may be
`explained by Fraser’s°? analysis in 1995, which attributes
`the clinical success of the ALIF to the surgical approach to
`the pathologic disk and not the fusion status,
`The more recent emergence ofLT cages enables surgeons
`to restore lumbar lordosis while achieving the similarly
`high fusion rates seen with cages. Burkuset al® compared
`LT cages implanted with rh-BMP-2 and FRA with autolo-
`gous bonegraft, and found no difference in outcomes, sup-
`porting the use of rh-BMP-2.© Havinganoff-the-shelf sub-
`stitute for autologous bonegraft allows surgeons to spare
`their patients the morbidity associated with donorsites,
`withoutsacrificing the osteoinductive properties needed
`for a fusion (Fig. 10.7).
`Although don’
`‘te morbidity has overshadowed au-
`tologous bone graiung, a prospective analysis was lack-
`ing. The senior author of this chapter participated in the
`first prospective analysis of over 200 spinal fusion patients
`randomized to an autologous donor arm and an rh-BMP
`arm comparing postoperative pain. Nearly onethird of the
`autologous donors had persistent donor-site pain 2 years
`postoperatively compared with zero pain in the rh-BMP
`randomized group.®! The ability to eliminate donor-site
`pain is an appealing option for the spine surgeon, despite
`appearing to be an added expense.
`A comparisonof an off-the-shelf osteoinductive growth
`factor reveals that they are in fact a cost-effective way of
`000008
`
`000008
`
`

`

`Surgical Managementof Low BackPain
`
`
`
`Fig. 10.7 Lateral radiograph of ALIF with an lumbar tapered (LT)
`cylindrical cage and BMP.
`
`decreasing patient morbidity and maximizing patient out-
`comes. This 2003 evaluation found that the cost of BMP
`is offset by reductions in other care expenses. For exam-
`ple, valuable OR time is reduced with the use ofa protein
`substitute, the postoperative periodis less painful, and less
`nursing staff woundcareis requiredfor the patient.”
`Reduction of OR time is beneficial for patients as well
`as for surgeons. Similar to using rnBMP, performing a 270-
`degree fusion (posterior instrumentation without fusion
`after an ALIF) versus a 360-degree fusion may be another
`effective way to trim OR time. A 2001 prospective random-
`ized trial failed to reveal anyclinical difference with the ad-
`dition of the posterior instrumentation. The Oswestry Low
`BackDisability Index (ODI) and the Numerical Rating Scale
`(NRS) were used to evaluate outcomesfollowing ALIF with
`or withoutposterior stabilization, and there werenostatis-
`tical clinical differences.©? Withoutclinical support of the
`posterior fusion, surgeons could chooseto decrease opera-
`tive supply cost (i.e., supplies needed for posterior fusion),
`shorten ORtime, and decrease intra/postoperative compli-
`cations.
`Evaluation of patient success can be addressed from
`many perspectives. A clinical evaluation may
`veal a
`pain-free patient with total resolution of symp
`1s de-
`spite a radiographic result that may be discordant, or vice
`versa. Using interval plain radiographs and computedto-
`mography (CT) scans, a recent study showsthat LT cages
`plus rhnBMP comparedfavorably with LT cages plus auto-
`graft, and those supplemented with rhBMPachieved more
`bone formation outside the cage. Both constructs formed
`bonesimilarly through the implant, but rhBMP improved
`bony fusion outside the cage. This confirms that rhBMP
`is not only comparable to autologous bone graft as an
`osteoinductive agent, but may be superior whenspecif-
`ically evaluating bone formation outside the stabilizing
`construct.®4
`
`
`
`
`
`Multiple papers support thestability of threaded caged
`and the clinical success;33%"* however, a recent retrospec. a i E jmplanted.
`tive review revealed an increased complication rate with©
`_
`Gompute
`
`threaded devices compared with nonthreaded trapezoidal _
`
`block-type constructs. This retrospective review identifieq 7
`
`a significantly higher numberof intraoperative complica.—
`
`tions with threaded devices and the tools used to prepare’ ~
`
`the site and insert the devices. The study also found more |
`
`postoperative complications; however,this wasnotstatis.
`
`tically significant. The greatest numbers of complications q
`
`seen were vascular in nature, including both intraopera- ©
`
`tive and postoperative. Most of these complications can be a
`
`iy following /
`linked to the added steps required to prepare the levelfor —
`
`the threaded device and the insertion instrumentation.2 —
`) ey: found a hig
`
`a ‘of seven pz
`Thesurgical techniques employed to expose the anterior ©
`
`lumbarspine focus on the preservation of adjacent struc- i
`show peri-i
`
`7 a. revision pli
`tures to minimize long-term complications. The anterior —
`
`scan and p
`lumbar spine can be approached via a transperitoneal or
`a -a metal im
`extraperitoneal approach using various i