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18 Anterior Spinal Column Augmentation Techniques
3. Galibert P, Deramond H. Percutaneous acrylic vertebroplasty as a treatment of vertebral angioma as
well as painful and debilitating diseases. Chirurgie.
1990;116(3):326–34. discussion 335
4. Galibert P, Deramond H, Rosat P, Le Gars
D. Preliminary note on the treatment of vertebral
angioma by percutaneous acrylic vertebroplasty.
Neuro-Chirurgie. 1987;33(2):166–8.
5. Allen RT, Kum JB, Weidner N, Hulst JB, Garfin
SR. Biopsy of osteoporotic vertebral compression
fractures during kyphoplasty: unsuspected histologic
findings of chronic osteitis without clinical evidence
of osteomyelitis. Spine. 2009;34(14):1486–91.
6. Garfin SR, Buckley RA, Ledlie J. Balloon Kyphoplasty
outcomes G. Balloon kyphoplasty for symptomatic
vertebral body compression fractures results in rapid,
significant, and sustained improvements in back pain,
function, and quality of life for elderly patients. Spine.
2006;31(19):2213–20.
7. Garfin SR, Yuan HA, Reiley MA. New technologies
in spine: kyphoplasty and vertebroplasty for the treatment of painful osteoporotic compression fractures.
Spine. 2001;26(14):1511–5.
8. Ghofrani H, Nunn T, Robertson C, Mahar A, Lee Y,
Garfin S. An evaluation of fracture stabilization comparing kyphoplasty and titanium mesh repair techniques for vertebral compression fractures: is bone
cement necessary? Spine. 2010;35(16):E768–73.
9. Perry A, Mahar A, Massie J, Arrieta N, Garfin S,
Kim C. Biomechanical evaluation of kyphoplasty
with calcium sulfate cement in a cadaveric osteoporotic vertebral compression fracture model. Spine
J. 2005;5(5):489–93.
10. Theodorou DJ, Theodorou SJ, Duncan TD, Garfin SR,
Wong WH. Percutaneous balloon kyphoplasty for the
correction of spinal deformity in painful vertebral body
compression fractures. Clin Imaging. 2002;26(1):1–5.
11. Diamond TH, Champion B, Clark WA. Management
of acute osteoporotic vertebral fractures: a nonrandomized trial comparing percutaneous vertebroplasty with conservative therapy. Am J Med.
2003;114(4):257–65.
12. Schreiber JJ, Anderson PA, Hsu WK. Use of computed tomography for assessing bone mineral density.
Neurosurg Focus. 2014;37(1):E4.
13. Weninger P, Schultz A, Hertz H. Conservative
management of thoracolumbar and lumbar spine
compression and burst fractures: functional and
radiographic outcomes in 136 cases treated by closed
reduction and casting. Arch Orthop Trauma Surg.
2009;129(2):207–19.
14. Gertzen H, Hallberg O, Laage-Hellman JE, Lundblad
L, Odelberg-Johansson O, Widstrom A. Radiotherapy
of differentiated thyroid neoplasms. Lakartidningen.
1978;75(34):2857.
15. Liu W, Zhou S, Wang S. Application of percutaneous
vertebroplasty in the treatment of multiple thoracic
metastases. Oncol Lett. 2015;9(6):2775–80.
16. Berenson J, et al. Balloon kyphoplasty versus nonsurgical fracture management for treatment of painful
vertebral body compression fractures in patients with
cancer: a multicentre, randomised controlled trial.
Lancet Oncol. 2011;12(3):225–35.
17. Cianfoni A, Raz E, Mauri S, et al. Vertebral augmentation for neoplastic lesions with posterior wall
erosion and epidural mass. AJNR Am J Neuroradiol.
2015;36(1):210–8.
18. De la Garza-Ramos R, Benvenutti-Regato M, CaroOsorio E. Vertebroplasty and kyphoplasty for cervical spine metastases: a systematic review and
meta- analysis. Int J Spine Surg. 2016;10:7.
19. Costa F, Ortolina A, Galbusera F, et al. Pedicle screw
cement augmentation. A mechanical pullout study on
different cement augmentation techniques. Med Eng
Phys. 2016;38(2):181–6.
20. Tan QC, Wu JW, Peng F, et al. Augmented PMMA
distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated
pedicle screw with diameter-tapered perforations.
J Neurosurg Spine. 2016;24:971–7.
21. Elder BD, Lo SF, Holmes C, et al. The biomechanics of pedicle screw augmentation with cement. Spine
J. 2015;15(6):1432–45.
22. Klingler JH, Scholz C, Kogias E, et al. Minimally invasive technique for PMMA augmentation of fenestrated
screws. ScientificWorldJournal. 2015;2015:979186.
23. Oner FC, Verlaan JJ, Verbout AJ, Dhert WJ. Cement
augmentation techniques in traumatic thoracolumbar
spine fractures. Spine. 2006;31(11 Suppl):S89–95.
discussion S104
24. McGraw JK, Cardella J, Barr JD, et al. Society of
Interventional Radiology quality improvement guidelines for percutaneous vertebroplasty. J Vasc Interv
Radiol. 2003;14(7):827–31.
25. McGraw JK, Cardella J, Barr JD, et al. Society of
Interventional Radiology quality improvement guidelines for percutaneous vertebroplasty. J Vasc Interv
Radiol. 2003;14(9 Pt 2):S311–5.
26. Stallmeyer MJ, Zoarski GH, Obuchowski AM.
Optimizing patient selection in percutaneous vertebroplasty. J Vasc Interv Radiol. 2003;14(6):683–96.
27. Papanastassiou ID, Filis A, Aghayev K, Kokkalis ZT,
Gerochristou MA, Vrionis FD. Adverse prognostic
factors and optimal intervention time for kyphoplasty/
vertebroplasty in osteoporotic fractures. Biomed Res
Int. 2014;2014:925683.
28. Svedbom A, et al. Balloon kyphoplasty compared
to vertebroplasty and nonsurgical management in
patients hospitalised with acute osteoporotic vertebral
compression fracture: a UK cost-effectiveness analysis. Osteoporos Int. 2013;24(1):355–67.
29. Wong W, Mathis J. Is intraosseous venography a significant safety measure in performance of vertebroplasty? J Vasc Interv Radiol. 2002;13(2 Pt 1):137–8.
30. Zaryanov AV, Park DK, Khalil JG, Baker KC,
Fischgrund JS. Cement augmentation in vertebral
burst fractures. Neurosurg Focus. 2014;37(1):E5.
31. Bae JW, Gwak HS, Kim S, Joo J, et al. Percutaneous
vertebroplasty for patients with metastatic compression
fractures of the thoracolumbar spine: clinical and
I.K. White et al.
radiological factors affecting functional outcomes.
Spine J. 2016;16(3):355–64.
32. Tezer M, Erturer RE, Ozturk C, Ozturk I, Kuzgun
U. Conservative treatment of fractures of the thoracolumbar spine. Int Orthop. 2005;29(2):78–82.
33. Lu WW, Cheung KM, Li YW, et al. Bioactive bone
cement as a principal fixture for spinal burst fracture: an in vitro biomechanical and morphologic
study. Spine 2001;26(24):2684–2690; discussion
2690–81.
34. Mermelstein LE, McLain RF, Yerby SA.
Reinforcement of thoracolumbar burst fractures
with calcium phosphate cement. A biomechanical study. Spine 1998;23(6):664–670; discussion
670–61.
Anterior Lumbar Interbody Fusion of the Lumbosacral Spine: L3 Through the Sacrum
J. Kenneth Burkus
Introduction
Degenerative disc disease in the lumbar spine is a
specific pain syndrome that originates from
changes and instability patterns within the intervertebral disc. This syndrome is diagnosed by a
history of clinical complaints, physical findings,
and neuroradiographic studies. Identifying
patients with a symptomatic degenerative disc
who will benefit from interventional treatment is
challenging. The selection of appropriate treatment modalities depends on the patient’s symptoms, physical findings, and diagnostic testing.
Discogenic pain syndromes are a continuum
of diagnostic categories that involve degenerative
conditions of the intervertebral disc [
clinical syndromes are commonly referred to as
internal disc disruption (IDD) and degenerative
disc disease (DDD). These degenerative pro-
cesses occur in the majority of people as the
result of aging. However, in addition to the
degenerative patterns seen with aging, certain
biologic and biomechanical factors predispose
some people to painful degenerative changes
J.K. Burkus, MD (*)
Attending Physician, Spine Service, The Hughston
Clinic, 6262 Veterans Parkway, Columbus,
GA 31908, USA
jkb66@knology.net
e-mail:
1]. These
19
within the spinal motion segment. Clinically
painful discs have been shown to have specific
patterns of altered stresses in the annulus and vertebral end plates. These heightened stresses
reflect abnormal biomechanical loading patterns
across the disc space.
The first clinical report on the treatment of
symptomatic degenerative lumbar disc disease by
anterior lumbar interbody fusion (ALIF) was published in 1948 [
internal disc disruption (IDD) based upon a retrospective analysis of patients who had continued to
complain of disabling back and leg pain after operations for lumbar disc prolapse [3]. Contemporary
reports of large clinical series of anterior lumbar
interbody fusion (ALIF) results have shown varying rates of fusion and differing clinical outcomes
[4–7]. Loguidice et al. [8] found ALIF had an 80%
rate of successful fusion and an 80% rate of clinical success. Blumenthal et al. [
cessful fusion rate and 74% clinical success rate.
Newman et al. [
with internal disc derangement had successful
clinical results following an ALIF procedure. A
successful fusion alone does not guarantee an
improved clinical outcome [11–14].
Interbody fusion devices have been introduced
recently that have been used to improve rates of
fusion, reestablish disc space height, and restore
normal sagittal contours [
characteristics of these implants provide significant advantages and benefits over traditional
2]. Crock later introduced the term
9] found a 73% suc-
10] found that 86% of their patients
15–17]. The design
© Springer International Publishing AG 2017
L.T. Holly, P.A. Anderson (eds.), Essentials of Spinal Stabilization,
DOI 10.1007/978-3-319-59713-3_19
227
228
J.K. Burkus
interbody fusion techniques including intersegmental distraction, immediate stabilization, and
facilitation of fusion. The intradiscal fusion
devices provide mechanical support that promotes fusion and prevents subsidence and disc
space collapse. Restoration of anatomic disc
space height and the reduction of any frontal or
sagittal plane deformities are important in reducing disabling complaints and enhancing clinical
outcomes [18–20].
A failed posterior spinal fusion can also be
salvaged with an ALIF procedure. A posterolateral or intertransverse process fusion provides
stability in the presence of rotational, translational, and iatrogenic instability patterns when
the disc is intact or is not the source of pain.
However, a posterior or posterolateral fusion
does not always restore the structural integrity of
a painful degenerative or unstable lumbar disc.
During the traditional posterior approach, the
paraspinal muscles are detached from the posterior spinal elements and transverse processes.
The loss of their normal anatomic attachment
sites, formation of scar tissue, and loss of independent muscle function compromise the paravertebral muscles. Lumbar spine stabilization
procedures that do not interfere with the posterior
spinal muscles or that limit posterolateral dissection offer some significant advantages.
Indications and Patient Selection
Anterior lumbar interbody fusion (ALIF) is an
effective treatment for patients with symptomatic
degenerative discogenic conditions that include
lumbar spondylosis, instability, and radiculopathy from L3 through the sacrum. One- or twolevel degenerative lumbar disc disease can be
treated with stand-alone anterior lumbar interbody fusion procedures; however, three-level
lumbar disc disease can rarely be treated by anterior interbody fusion alone. This condition usually requires additional posterior segmental
spinal stabilization.
These treatable degenerative conditions of
the lumbosacral spine are manifested by persistent back pain and referred leg pain that are
recalcitrant to nonoperative treatment modalities. Patients often exhibit restricted range of
motion of the lumbar spine, tenderness to palpation over the affected lumbar motion segments,
and paravertebral muscle spasm. They commonly describe pain that is exacerbated by
activities and that is relieved with rest. Sitting
can be uncomfortable, and patients frequently
complain of difficulty finding a comfortable
position. Pain is commonly referred to the buttock and posterior aspect of the thigh. This
referred leg pain pattern rarely extends below
the knees and radiates in a nondermatomal distribution into the lower extremities. Objective
neurologic deficits, such as diminished or
altered sensation and depressed reflexes, can be
demonstrated; however, significant motor weakness, such as a foot drop, is rarely seen in
patients suffering from these degenerative conditions. These patients do not commonly have
positive sciatic tension signs. Straight-leg raising usually causes low back pain and referred
buttock and posterior thigh pain.
Degenerative disc disease can be readily identified in symptomatic patients with plain radiographic findings. Degenerative changes within
the lumbar motion segment are evidenced on
plain radiographs by disc space collapse, radial
osteophyte formation, and vertebral end plate
sclerosis. Plain radiographs can also identify specific patterns of segmental instability by demonstrating excessive translational or rotational
segmental motion at the intervertebral disc space.
Painful instability patterns include spondylolisthesis, retrolisthesis, lateral listhesis, rotatory
subluxation, and scoliosis. These abnormal
motion patterns may require dynamic stress
radiographs to be seen. Radiographic criteria for
sagittal or rotational instability have been established and involve angular displacement on a
flexion-extension lateral radiograph or translational shift to be considered in this diagnostic
group. Segmental imbalance and loss of normal
sagittal contours can also cause painful symptoms from the overloading of the facet joint and
muscle fatigue.
Sagittal plane deformities with more than
20% subluxation cannot be treated reliably and
19 Anterior Lumbar Interbody Fusion of the Lumbosacral Spine: L3 Through the Sacrum
229
predictably with a stand-alone anterior interbody
fusion. Similarly, patients with severe segmental
instability, as evidenced by more than 5 mm of
sagittal plane translation on dynamic flexionextension lateral radiographs, are not candidates
for anterior interbody fusion alone. These patients
would require additional posterior stabilization.
Imaging studies, such as magnetic resonance
imaging (MRI), are helpful in identifying degenerative disc disease. MRI scans confirm desiccation of the disc and often Modic changes in the
adjacent vertebral end plates [21]. However, disc
desiccation, radial annular tears, and highintensity zones documented on MRI are not, by
themselves, indications for surgery. Correlative
discography may be helpful in identifying the
painful disc levels. Importantly, discography cannot be used alone to identify painful disc levels.
Discography is often not effective in reproducing
concordant pain stimulation at the affected level.
The annulus of the disc can be incompetent, and
distension of the annular pain fibers is not the primary source of pain. Discography may be helpful
in the diagnostic evaluation by assessing adjacent
spinal segments.
The level of bifurcation of the great vessel is
highly variable. Most commonly, it occurs over
the L5 vertebral body. The bifurcation of the vessels should be identified on preoperative neuroradiographic studies; evaluation of the axial cuts of
preoperative MRI images or CT scans can help to
identify the level of the bifurcation. These studies
are essential when anterior instrumentation is
being considered to stabilize the intradiscal
implant. In addition, occult calcification of the
great vessel can be seen on these studies.
Preoperative Considerations
Identifying patients with symptomatic degenerative disc disease who will benefit from surgical
treatment is challenging for the physician.
Approximately 30% of asymptomatic subjects
have degenerative changes on plain radiographic
studies. The selection of appropriate treatment
modalities depends on the patient’s symptoms,
physical findings, and diagnostic testing. Only
one-third of those patients who have pain for
more than 3 months develop significant disabling
symptoms that warrant further diagnostic
evaluation.
Before surgery is considered, patients should
be treated with vigorous aerobic lumbar conditioning programs that include isometric trunkstrengthening exercises and flexibility exercises.
Nonimpact aerobic exercise, such as swimming
or warm-water hydrotherapy, is well tolerated by
these patients. In addition, isometric trunkstabilization strengthening exercises consisting
of a series of rigorous abdominal and paraspinal
isometric exercises performed without much
trunk mobilization have proven beneficial.
Chiropractic manipulation has been found to
be effective in the treatment of short-duration low
back pain. Similarly, the use of a nonnarcotic
anti-inflammatory medication and the use of
muscle relaxants are indicated for short-term
relief of pain. The use of narcotic pain medication for the control of chronic pain is not efficacious. Neither bracing nor the use of acupuncture
offers any substantial advantage in the treatment
of discogenic pain syndromes.
Patients with previous disc space infection,
metabolic bone disease, or osteoporosis also cannot be effectively treated with stand-alone anterior lumbar interbody fusion. The interbody
fusion cages rest on the bony end plates of the
intervertebral disc space. In patients with osteoporosis, the host trabecular and cortical bone cannot sustain the stresses from the cages. Microstress
fractures occur, and the cages subside through the
end plates and into the trabecular bone of the vertebral body. Subsidence leads to loss of soft tissue
tensioning and instability at the disc space.
Subsidence of the implants is also associated with
loss of lordosis and loss of foraminal height. The
micromotion associated with subsidence can lead
to a delayed union or fibrous nonunion.
The overriding concern for the treating physician is proper patient selection. The majority of
patients with discogenic pain do not require surgical treatment. Fusion surgery, or arthrodesis,
should be reserved for patients who are highly
motivated, carefully selected, and without psychological magnification of their symptoms.
230
J.K. Burkus
Surgical Technique
Patient Positioning
The patient is placed in the supine position on the
operating room table. The table must accommodate fluoroscopy in both the anteroposterior and
lateral dimensions. The patient’s arms may be
tucked to the sides or suspended laterally from
the table. Importantly, the arm position should
not interfere with the fluoroscopic visualization
of the spine. A radiolucent roll is placed under
the lumbar spine and directly underneath the
affected lumbar motion segment. The lumbar roll
increases lumbar lordosis and frequently opens
the collapsed disc space. This maneuver facilitates intraoperative distraction of the disc space
and often partially reduces any sagittal plane
deformity.
The lumbar spine is visualized in both the
anteroposterior and lateral dimensions. The spine
is checked for rotation. The posterior spinous
process should be able to be well visualized
between the pedicles. After a radiographic
marker is placed on the skin, fluoroscopy is used
to confirm its optimal position over the disc
space. The entire abdomen and pelvis are prepared and draped in the surgical field in the usual
and sterile fashion.
the posterior rectus sheath bluntly separates from
the peritoneal sac starting inferiorly and working
superiorly and laterally. The posterior rectus
sheath can be sharply incised and blunt dissection continued. A fatty plane is encountered
directly overlying the psoas muscle. The entire
peritoneal sac is then easily reflected past the
midline. The ureter can be seen within the peritoneal sac crossing the iliac vessels. Care is taken
to ensure that the left ureter is retracted along
with the peritoneal contents. The genitofemoral
nerve is seen lying directly on top of the psoas
muscle. This nerve should not be mobilized.
The bifurcation of the great vessels occurs
most commonly over the L5 vertebral body and
should be identified on preoperative imaging
studies. The L5–S1 disc space is most often
located directly inferior to the bifurcation of the
iliac vein, and the L4–L5 disc space is usually
found directly lateral to the bifurcation of the
iliac artery. The L4–L5 disc can be palpated at
the junction between the bifurcation of the iliac
artery and the psoas muscle. The sacral promontory and the L5–S1 disc can be palpated directly
below the iliac vein bifurcation.
Exposure of the L3–L4 and L4–L5 Disc Spaces
Open Retroperitoneal Exposure of the Lumbosacral Spine
A vertical or transverse skin incision is made
over the appropriate disc space. The incision is
sharply carried down through subcutaneous tissues. The ventral portion of the rectus abdominus
muscle sheath is exposed. The muscle sheath is
divided vertically approximately 2 cm from the
midline. The medial border of the rectus abdominus muscle is bluntly dissected free from the
muscle fascial sheath, and the rectus abdominus
muscle is mobilized with blunt dissection and
retracted laterally.
The arcuate line and posterior rectus sheath is
visualized. The posterior rectus sheath is often a
very thin layer overlying the peritoneal sac. First,
The L4–L5 disc space is initially identified with
gentle palpation along the medial border of the
psoas muscle adjacent to the bifurcation of the
iliac artery. The rounded soft annulus is readily
identified. The L3–L4 disc space can be localized
in the same plane, approximately 4 cm cephalad
to the iliac bifurcation.
Direct dissection is carried down on top of the
disc space through an avascular plane. Once the
anterior surface of the annulus has been exposed,
soft tissues can be swept off the disc space medially and laterally. Segmental vessels tether the
aorta, vena cava, and iliac vessels. The segmental
vessels lie in the midportion of the vertebral bodies of L3 and L4.
In exposing the L3–L4 disc space, the segmental vessels above and below the disc space
must be identified, ligated, and divided. After this
19 Anterior Lumbar Interbody Fusion of the Lumbosacral Spine: L3 Through the Sacrum
231
maneuver, blunt dissection allows the surgeon to
mobilize the great vessels well past the midline
of the disc space.
Exposure of the L4–L5 interspace requires the
surgeon to mobilize the left iliac artery and vein.
Once the disc space has been identified, dissection is bluntly carried cephalad, and segmental
vessels crossing the midportion of the L4 vertebral body are identified, ligated, and divided.
With blunt dissection, the iliac artery and aorta
can be gently reflected past the midline. Directly
under the artery is the left iliac vein. Before the
vein is mobilized, blunt dissection must be carried out inferiorly along the lateral border of the
left iliac vein. The recurrent iliolumbar vein
should be identified. This lateral branch of the
left iliac vein often needs to be securely ligated
and divided to adequately mobilize the vein. The
iliac artery and vein can then be reflected past the
midline, exposing the L4–L5 disc space.
Exposure of the L5–S1 Disc Space
The L5–S1 disc space can be palpated gently
within the bifurcation of the great vessels. Blunt
dissection is carried down directly on top of the
left iliac artery. Underneath the artery is the left
iliac vein. Soft tissues should be separated from
the vein and bluntly mobilized past the midline of
the disc. Dissection is carried out superiorly to
the bifurcation of the iliac vein. All soft tissues
are then bluntly swept from left to right. The middle sacral artery and vein are exposed after this
maneuver. These vessels are sequentially identified, ligated, and divided; they should not be cauterized. The disc space is further exposed with
blunt dissection. Quite frequently, the left iliac
vein must be retracted laterally and superiorly.
Superior Hypogastric Plexus and Retrograde Ejaculation
In male patients, retrograde ejaculation (RE) is a
potential complication of anterior lumbar interbody fusion. The reported incidence of retrograde ejaculation after anterior lumbar interbody
fusion varies widely in the literature. Plausible
causes include direct injury to nerve and inflam-
mation. Proposed various factors related to an
increased risk of RE include the use of rhBMP-2,
the interbody implant used, surgical approach,
surgical technique (use of monopolar electrocautery), and surgeon experience.
The pelvic preaortic sympathetic plexus travels down from the thoracolumbar sympathetic
chain in the retroperitoneal space. The superior
hypogastric plexus is the terminal extension of
this plexus. It lies anterior to the aorta and vertebra and covers the iliac bifurcation. The plexus
has a variable structure. The nerve fibers are most
commonly found arching over the left iliac artery
crossing the L51 disc space. The hypogastric
plexus can be injured by removing prevertebral
tissue from the front of the L5–S1 disc space or
by liberal use of electrocautery in the
bifurcation.
Blunt dissection of presacral tissues, lateral
retraction of these tissues, and avoidance of electrocautery in the bifurcation preserve the sympathetic plexus. No transverse incisions across the
disc interspace are made until the annulus is
clearly exposed and isolated from all soft tissues.
For transperitoneal midline approaches, the posterior peritoneum must be careful opened. A
sharp incision should be made over the level of
the bifurcation and extended inferiorly over the
L5S1 disc space. Electrocautery should not be
used. Blunt dissection should begin on the right
side of the disc space, and soft tissues should be
swept from right to left across the disc space.
The Bulldog Discectomy
A complete anterior discectomy is carried out.
The entire anterior portion of the vertebral body
should be readily visualized. The rounded anterior surface and anterior longitudinal ligament
and lateral borders of the annulus should be
exposed. A radiographic marker is placed in the
midportion of the disc space. Its position is confirmed with fluoroscopy in both the anteroposterior and lateral dimensions. The cartilaginous end
plates are separated from the bony end plate.
Great care is taken to preserve the bony end
plates. Dissection is carried out lateral and
232
J.K. Burkus
posterior with the disc space. The lateral portions
of the annulus must also be preserved. The posterior annulus and posterior radial osteophytes may
be removed under direct visualization. Contained
disc protrusions and disc herniations can be
removed through this approach.
Following the thorough discectomy, the disc
space can be mobilized. Distraction can be
achieved with the use of serial impacted dilators.
Expansion of the collapsed disc space re-tensions
the soft tissues and ligamentous structures surrounding it. Anterior distraction maneuvers often
reduce sagittal plane deformity (spondylolisthesis, retrolisthesis), reduce lateral plane deformity
(scoliosis, lateral listhesis), and increase lumbar
lordosis by tensioning the surrounding soft tissue
elements. Establishing normal disc space height
indirectly decompresses the neuroforamina and
enlarges the neuroforaminal opening. Distraction
of the disc space tensions the annulus fibrosus
and compresses the interbody implant.
Disc space distraction should be limited to
the anatomic restoration of disc space height
assessed on preoperative standing plain lateral
radiographs. Anterior intradiscal distraction
instruments are powerful and can easily overcome the stabilizing soft tissue elements of the
disc space. Overdistraction should be avoided.
Similarly, segmental hyperlordosis of the disc
space should be avoided. Templates are available that enable the surgeon to accurately measure the disc space height of adjacent normal
discs. Having an understanding of anatomic disc
space height, the surgeon can anticipate the
amount of disc space distraction necessary to
achieve uniform tensioning of the soft tissue
elements across the disc space in the operating
room. Fluoroscopy and tactile feedback is used
to assess disc space expansion and reduction
and any sagittal deformity during the impaction
of the disc space distracters.
Interbody Implants
Structural autografts and allograft impacted
intradiscal spacers have been a popular graft
source and have a long and well-documented
record of clinical safely and efficacy. Advanced
biomaterial options, such as titanium, resorbable
polymers, carbon fiber, and PEEK (polyetheretherketone) materials, are also available.
These materials have proven biocompatibility,
excellent chemical stability, and good mechanical properties. The implants differ in their modulus of elasticity. The PEEK material is comparable
to bone, which minimizes stress shielding following implantation and is radiographically
transparent. Synthetic polymers are increasingly
used as alternatives to titanium not only because
of their mechanical properties but also because of
their properties in terms of molding, processing,
and in vivo radiographic imaging. In assessing
postoperative fusion, these implants have no
imaging interference—osteoinduction and bone
graft maturation can be demonstrated on radiographs without artifact.
Porous metal implants and PEEK implants
with porous or rough metal coatings have found
their way into clinical use. Both titanium and
PEEK materials are currently being enhanced
with several physical and chemical surface treatments which have been shown to improve osseointegration into the host bone. Implant surface
treatments alter the micrometer- or nanometerscale surface roughness with a high degree of
precision. These surface treatments promote
osteoblastic differentiation and foster a specific
cellular environment that enhances bone formation. The long-term clinical and radiographic outcomes from the use of the advanced materials
have not been established.
The shape of the vertebral body is important
in planning the depth of insertion of the spinal
implants. The implants should be recessed within
the confines of the intervertebral disc space. The
implants should contact the vertebral apophysis
but remain well seated within the intervertebral
disc space. Axial sections of preoperative MRI
and CT scan will help to document the size of the
implants to be used.
Cage Choices
Stand-alone anterior interbody implants can be
impacted or threaded. The impacted implants are
driven into the disc space. Preoperative evaluation
19 Anterior Lumbar Interbody Fusion of the Lumbosacral Spine: L3 Through the Sacrum
233
of plane radiographs and axial images of the spinal motion segments are important in planning
and establishing the goals of an anterior interbody fusion. Preoperative templating helps to
ensure that the appropriate interbody fusion cage
is selected for each interspace. It also aids the
surgeon in planning the extent of intraoperative
distraction necessary to tension the annulus fibrosus adequately and to reestablish the normal anatomic relationship of the intervertebral motion
segment. The intradiscal implant should be
placed parallel to the end plates of the adjacent
vertebra. The anterior head wall of the device
should be seated along the anterior margins of the
vertebral bodies. The device should not penetrate
the posterior or posterolateral corner of the disc
space. The shape of the vertebral body must be
evaluated on axial scans to determine how deeply
the cages can be inserted in the disc space without risks of posterolateral perforation.
Depending upon the bone quality, the intradiscal implant can be used as a stand-alone device or
supplemental fixation can be used. An anterior
plate can be fixed to the vertebral bodies. The
plate must be placed away from contact with
adjacent vascular structures and therefore is most
commonly used at the L5S1 disc level. The intradiscal device itself can incorporate screws or fins
that insert into the adjacent vertebral bodies.
Expandable devices within the disc space can be
used. Hyperlordotic implants should be avoided.
The implant should match the geometry of the
disc space following appropriate distraction. The
implant should not establish segmental
hyperlordosis.
Bone Graft/Substitute
The standard for bone grafting in spinal fusion
procedures has long been autogenous cancellous
bone harvested from the iliac crest. Autologous
bone grafts provide osteoinductive and osteoconductive elements that are not immunogenic and
are usually well incorporated into the transplantation site. Harvesting autogenous bone grafts for
spinal surgery has been associated with many
complications; recent publications have also doc-
umented the long-term incidence of donor site
pain to occur in 22–45% of the patients.
Contemporary bone grafting options eliminate
the high rates of complications associated with
autogenous bone harvesting. The biologic activity and structural composition of these grafting
materials determine whether these materials are
used as bone graft extenders or bone graft
replacements. Human cadaver allograft bone
products have an osteoconductive scaffold; however, they have minimal osteoinductive factors.
Demineralized bone matrices (DBMs) are the
product formed by the acid treatment of allograft
bone. DBMs do not have structural strength but
possess osteoconductivity and the osteoinductive
growth factors. The osteoinductive ability in
DBMs to stimulate bone regeneration is dependent upon the activity of the bone morphogenic
proteins (BMPs). DBM does not function as a
replacement for autograft; it expands the volume
and enhances the inductivity of autograft but
does not replace it.
Ceramic scaffolds are not osteoinductive or
osteogenic. They do not enhance the ability of the
graft material to form new bone; they have not
been demonstrated to perform comparable to
iliac crest autograft in lumbar fusions. They cannot be used alone in spinal fusions; ceramics are
not bone graft substitutes.
Platelet gels contain multiple growth factors
but do not contain any BMPs; they are not
regarded as osteoinductive. They encourage local
cellular proliferation but are unable to induce
bone formation alone and are not capable of
mediating the process of bone formation. These
gels have little clinical evidence of their efficacy
and also cannot be used alone as a bone graft
substitute.
Only bone morphogenetic proteins are capable
of inducing the entire bone formation cascade. It
is this unique property that allows these proteins
with a suitable carrier to be used as a bone graft
replacement. Recombinant human bone morphogenetic protein-2 (rhBMP-2) is an osteoinductive
protein that when combined with the proper carrier (absorbable college sponge ACS) at an appropriate concentration has the potential to obviate
the need for autogenous bone grafting. The use of
234
J.K. Burkus
rhBMP-2/ACS was shown to be an effective treatment in inducing fusion as well as improving pain
and function in subjects with single-level lumbar
degenerative disc disease. The fusion rate in those
patients treated with rhBMP-2/ACS was significantly higher than those patients treated with
autogenous bone grafts. Recent studies using
pooled data have confirmed that patients with
radiographically confirmed fusion had significantly better improvements in clinical outcomes
than those of patients with radiographic nonunion.
Additional studies have reported decreased reoperation rates are caused by the improved fusion
with the use of rhBMP-2/ACS. Appropriately
dosed rhBMP-2/ACS can be used in patients who
are at risk for developing a pseudarthrosis following lumbar intradiscal fusion surgery.
Supplemental Fixation
Supplemental posterior stabilization should be
considered if there is any residual sagittal or frontal plane deformity following the interbody
fusion. Patients with osteoporosis, patients at risk
of pseudarthrosis, patients who have undergone a
posterior decompression, and those patients
desiring aggressive postoperative mobilization
can befit from posterior stabilization.
nique is feasible for exposure from L3 through
the sacrum. This approach to the lower lumbar
spine for arthrodesis may be associated with a
higher incidence of complications than open
techniques [22, 23].
Illustrative Case
A 51-year-old white male had incapacitating low
back pain and referred bilateral leg pain into his
buttocks and posterior thighs. He had undergone
an L5–S1 discectomy in the remote past. He had
no complaints of pain radiating below his knees.
His symptoms were exacerbated with activities
and partially relieved with rest. His symptoms
were recalcitrant to a 6-month course of physical
therapy, anti-inflammatory medications, and antispasmodic medications.
An anteroposterior lumbar radiograph shows
bilateral laminotomy defects at L5 (Fig. 19.1).
A standing lateral radiograph shows 3 mm of
retrolisthesis at L5–S1 (Fig. 19.2). There is significant narrowing of the neural foramina at L5–
S1 secondary to the retrolisthesis and disc space
narrowing (arrow). Figures 19.3 and 19.4 demonstrate the disc space narrowing, anterior
osteophyte formation (arrow), and retrolisthesis
at L5–S1 and normal motion patterns at discs
above that level.
Closure
The great vessels are inspected to ensure that there
have been no injuries. The ureter and retroperitoneal
structures are also inspected. The wounds are then
closed, along with any inadvertent perforations in
the peritoneum. No attempts are made to suture the
posterior rectus sheath. The anterior rectus sheath is
approximated with divided absorbable sutures and
the wound margins are approximated with a subcuticular stitch.
Oblique Lumbar Approach
A minimally invasive retroperitoneal oblique
lumbar interbody fusion (OLIF) has been developed [10]. The minimally invasive OLIF tech-
Fig. 19.1 Anteroposterior lumbar radiograph