ADVANCES IN MANAGING SPINAL DISORDERS
Selections from the Fifth Annual Symposium on Current Concepts in Spinal Disorders 2006
| SELECTION CRITERIA FOR CERVICAL ARTIFICIAL DISC REPLACEMENT —Christopher J. Zarembinski,
MD, Chief, Acute Pain Services, Cedars-Sinai Medical Center, Los Angeles, CA
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| General indications for anterior cervical artificial disc replacement (ADR): similar for anterior cervical
decompression; radiculopathy or myelopathy caused by 1 or 2 levels of anterior cervical compression; treat conservatively;
adverse effects of cervical fusion—adjacent segment degeneration; difficulties in treatment after fusion; plating
complications; perioperative immobilization; bone graft site morbidity; pseudoarthrosis; dysphagia; Hilibrand
study—374 patients having 409 cervical arthrodeses for up to 21 yr; 3% incidence of developing adjacent segment disease;
projection that 26% of patients would have new disease at adjacent level (C5-C6 and C6-C7) within 10 yr after
surgery; adjacent levels showed increased range of motion and intradiscal pressures; reoperative challenges—disc
space adjacent to solid fusion challenging environment, biomechanical differential in stiffness between fusion below
and open segment above; iliac crest complications; up to 25% incidence of chronic pain, including meralgia paresthetica;
pelvic fracture; risk for sacroiliac joint injury; inferior gluteal artery injury
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| Cervical ADR criteria: from Food and Drug Administration (FDA) trials; inclusion criteria—patients requiring
surgical treatment at 1 to 2 levels from C3 to T1 with disc herniation and radiculopathy, spondylotic radiculopathy, disc
herniation with myelopathy, or spondylotic myelopathy; patients who have failed 6 wk of conservative treatment; focal
compression lesion documented radiographically; abnormal neurologic sign indicative of radiculopathy or myelopathy;
patients between 18 and 65 yr of age; major role of cervical disc replacement will be adjacent to already established cervical
fusion with adjacent segment spinal compression; treatment of patients with primary discogenic axial neck pain
with disc replacement controversial and needs further study; exclusion criteria—patients with ankylosing spondylitis,
rheumatoid arthritis, diffuse idiopathic skeletal hyperostosis (DISH), ossification of posterior longitudinal ligament
(OPLL), diabetes mellitus, previous cervical spine infection, long-term steroid use, morbid obesity, pregnancy; axial
pain as solitary symptom; narrow cervical canal with anteroposterior (AP) diameter <10 mm; severe arthritis of facet
joints; osteoporosis; metallic allergy; tumor; radiographic instability
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| Diagnostic spinal injections: improve outcome of patients with artificial disc technology; to more fully evaluate
patients with axial and radicular components; determine pain generator in multilevel disease; assess patient’s validity
and compliance when behavioral issues suspected; assess postoperative patient with complex recurrent pain;
facet (z-joint) injection—important because radiographs, history, and physical examination not specific for cervical,
thoracic, or lumbar z-joint–mediated pain; well-defined referral zones based on joint involved; helpful clinically;
selective nerve root block (SNRB)—93% correlation with surgical lesion; patients with >1 yr of radicular
pain who did not have long-term response to SNRB had poor surgical outcome; injection of corticosteroids during
SNRB had good negative predictive value; use test dose of local anesthetic before corticosteroid injection; use microbore
extension tubing to minimize needle manipulation; minimize sedation to allow earlier detection of central
nervous system dysfunction; needle tip in posterior aspect of neuroforamen; discography—history and physical
examination unreliable in diagnosing discogenic pain; patient with elevated scores on hypochondriasis, hysteria,
and depression scales of Minnesota Multiphasic Personality Inventory (MMPI) overreport pain; discordant pain response
should be cautiously interpreted, even with concordant imaging; best discogram negative; referral patterns
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| Psychologic factors and outcome: Hurme noted that social and psychologic factors influenced outcome more than
preoperative physical examination findings or grade of operative findings in patients undergoing initial decompression;
Spengler noted that patients with disc herniation and distinctly abnormal score on MMPI had poor surgical outcome;
patient selection red flags—patients having multiple complications with previous invasive procedures need to
be approached cautiously; patients with predominance of nonorganic findings on physical examination; patients with
active litigation; history of drug abuse or antisocial behavior; elevated hypochondriasis and hysteria scale scores on
MMPI
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| FUTURE PROSPECTS FOR GENETIC DISC REPAIR— Alexander R. Vaccaro, MD, Professor, Neurosurgery and
Orthopedic Surgery, Thomas Jefferson University School of Medicine, and Co-Director, Regional Spinal Cord Injury
Center of Delaware Valley, Philadelphia, PA
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| Research goals: develop strategies to emulate and combat disc degeneration through growth factor techniques, genetic
repair, and cellular therapy; reverse or stabilize disc degeneration process; increase synthesis and retard catabolism
through multiple mechanisms; models—bead model or pellet system where cells develop growth factors to
stimulate growth; whole disc model grown in culture, looking at disc height regeneration or collapse; cells respond
to growth factor in vitro; proteoglycan and collagen synthesis; cell has finite life span; Kang (University of Pittsburgh)
replaced cassette of target gene with therapeutic gene; cell continued to produce therapeutic target gene over
time; must now identify genes upregulated during degenerative process and develop strategies to attack degenerative
cascade
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| Models used: speaker’s laboratory uses induced disc degeneration annular injury; laboratory findings applied to clinical
situations (eg, hemostat used to grasp fascia covering disc); studied upregulation of matrix metalloproteinase
(MMP)1, MMP9, MMP13, and fibronectin after injury to disc; Kang’s laboratory showed correlation of histology,
magnetic resonance imaging (MRI), and radiographs over time if disc injured; redelivery of N-terminal fibonectin
fragment to animal model induced chemical degeneration; developing models that use enzymes to break down production
of proteoglycans, and antisense technology to bind to DNA and prevent replication of disc degeneration products;
Kang’s laboratory credited with placing therapeutic genes in animal model; showed that models work and can
sustain production of target protein over time; using appropriate target gene, proteoglycan and type 2 collagen production
can be induced; can regenerate disc in animal model; multiple target genes have additive effect in producing different
proteins
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| Cellular regeneration: research focuses on developing ways to stimulate one zone disc to regenerate itself; taking
mesenchymal stem cells from postterminal adult cells and exposing to hypoxic environment enables them to function
as nucleus pulposus cells; laboratories also studying ways to regenerate disc from itself
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| LUMBAR ARTIFICIAL DISC REPLACEMENT— Hallett H. Mathews, MD, Associate Clinical Professor, Orthopedic
Surgery and Surgery, Virginia Commonwealth University, Medical College of Virginia, Richmond
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| Motion preservation: combination and coordination of muscle relaxation and motion of spine to help in initiating
motion; ligament, muscle, and soft tissue disruption must be calculated along with preoperative disease for good surgical
result; ligament tension and stiffness important; does device need complete range of motion or does it need acceptable
amount of range of motion to reload spine? improvement through reloading and rebalancing of spine;
reemphasis of facet joint staging before surgery; important in orientation and prediction of disc herniation based on
natural facet orientation; much load on anterior and posterior columns; destabilization naturally or with discectomy
important; understand neutral zone; want to restrict bad motion, reload spine, and couple motions to get segments
fluid and get soft tissue support in less invasive way to rebalance spine
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| Mobile stabilization devices: nucleus and disc replacements; dynamic stabilization; historical standard nonmobile
static stabilization; contraindications for arthroplasty outweigh indications; different morbidities; 3% to 5% of patients
should be considered for mobile restabilization; combination of multilevel pathology at different degrees of degeneration;
restabilization process must be considered for individual assessment of specific spinal segment morbidity; must be
good diagnostician and understand problem beforehand; use imaging studies along with pain source to understand cascade
of events (eg, stenosis, discogenic pain, instability); devices applied to different phases of continuous degenerative
cascade
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| Disc replacement: aim to restore mobility, height, and sagittal balance; remove painful annular pathology, degenerative
inflammatory disc disease, and osteophytes; load bearing important to rebalance spine; center of rotation different
at each level; posterior center of rotation more important for some prostheses; more important that surgeon place prosthesis
in appropriate position (most important indicator); angular motion important; translation motion not important;
ball-and-socket prostheses have controlled angular motion; want disc replacement to restabilize and never be more mobile
than intact segment; wear debris testing favorable for cobalt chrome; long-term metal-on-metal toxicity not problematic
for arthroplasty or disc replacement; nominal amounts of wear debris from Maverick; anterior surgery
requires new learning curve; new set of complications; retroperitoneal approach—has anatomic restrictions; ascending
iliolumbar vein system and retraction of vessels important; can control good anatomic dissection and anterior
column surgery
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| Maverick study: cobalt chrome metal-on-metal, ball-and-socket design with hydroxyapatite (HA) coating; keel
and combination HA coating provide short- and long-term fixation; FDA design rationale—metal-on-metal, long-
term durability; one-step insertional technique; surgeon-intuitive device designed by surgeons; one-piece, simple
insertion—good end plate preparation, midline dissection, controlled anulotomy, keel cut up and down, good mobilization
using posterior wall
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| InFUSE study: first FDA Investigational Device Exceptions (IDE) study to use InFUSE in disc space as biologic
fusion stimulator with anterior column only stand-alone device; 21 of 28 patients did not have facet changes at 2 yr;
7 had 0 to 1 change at 2 yr; good range of motion; ensure prosthesis in midline
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| European balance study: looking at ability to reset sagittal balance; can improve local lordosis that has collapsed
from segmental degeneration; spine rebalances at adjacent levels; overall lordosis of entire lumbar spine unchanged;
information helpful in understanding rebalancing and facet loading changes after arthroplasty; rebalancing
spine major benefit of motion preservation
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| MINIMALLY INVASIVE SURGERY (MIS) AND DAILY PRACTICE —Kevin T. Foley, MD, Associate Professor,
Department of Biomedical Engineering, University of Tennessee School of Medicine, and Director, Complex
Spine Program, Semmes-Murphy Clinic, Memphis
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| Technique: use of very thin-walled tubular retractor using principles of magnification and illumination; effectively removes
lumbar disc; expanded to other spinal applications (eg, far lateral discectomy, posterior cervical discectomy, thoracic
discectomy, fusion); speaker uses approach similar to lumbar approach; patient in prone position; incision 1.5 cm
off midline using 14-mm tubular retractor; performs laminar foraminotomy at cervical root; same neural outcome using
open procedure vs minimally invasive surgery (MIS); relief of radiculopathy in equivalent fashion; short hospital stay,
quick return to work; other applications—posterior cervical laminar foraminotomy through MIS approach as outpatient
procedure; lumbar decompressive surgery routinely done in minimally invasive, effective fashion; MIS in invasive
spinal reconstruction—combining small retractors while placing fixation in more traditional location through MIS approaches;
technique used routinely by speaker; MIS used to supplement anterior lumbar interbody fusion (ALIF), posterior
lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), and onlay and facet fusion,
coupled with effective decompression techniques; all approaches evolving
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| MIS FIXATION IN THORACOLUMBAR TRAUMA— Mark B. Dekutoski, MD, Associate Professor of Orthopedics,
Mayo Clinic College of Medicine, Rochester, MN
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| Trauma management goal: return patient to activity, function, social role, and economic productivity at limited
societal cost
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| CD HORIZON SEXTANT Spinal System: posterior tension band; off-label use of implantation system; not approved
for anterior column deficiencies; selective applications—in anterior column restoration to prevent graft collapse;
increases healing; mobilizes patient without brace; use in bending and rotational injuries; use as posterior
tension band or with anterior column restoration over unfused segments (eg, balloon kyphoplasty, supplemented dorsally
to avoid collapse); selective fusion with ligamentous injury; bending, ligamentous injury (bony dorsally); holds
patient in position; used in lieu of cast or fixator; prevents kyphosis; percutaneous instrumentation will be used more
in polytrauma (chest, pelvic, long-bone injury) patients; axial loading injuries with morbid obesity; patients with mechanical
pain and metastatic disease; patients with hematogenous disc space infection and comorbidities (eg, obesity,
diabetes); future applications—multisegment system to span more levels, provide more stable fixation and reduction
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Educational Objectives
| The goal of this program is to educate the clinician about cervical and lumbar artificial disc replacement and minimally
invasive surgery (MIS) in spinal disorders. After hearing and assimilating this program, the clinician will have
a better understanding of:
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 | 1. Review the selection criteria for anterior cervical artificial disc replacement.
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| 2. Discuss the research goals and applications of genetic disc repair.
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| 3. Summarize the benefits of using mobile stabilization devices.
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| 4. Discuss the findings of the Maverick, InFUSE, and European balance studies.
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| 5. Review the applications of MIS.
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Suggested Reading
Acosta FL Jr et al: Cervical disc arthroplasty: general introduction. Neurosurg Clin N Am 16:603, 2005; Acosta
FL Jr et al: Emerging directions in motion preservation spinal surgery. Neurosurg Clin N Am 16:665, 2005; Amini
A et al: Thoracoscopic spine surgery for decompression and stabilization of the anterolateral thoracolumbar spine.
Neurosurg Focus 19:E4, 2005; Baron EM et al: Neuroendoscopy for spinal disorders: a brief review. Neurosurg
Focus 19:E5, 2005; Chang BS et al: Evaluation of the biological response of wear debris. Spine J 4:239S, 2004;
Chen Y: Orthopedic applications of gene therapy. J Orthop Sci 6:199, 2001; Chiu JC et al: Junctional disc herniation
syndrome in post spinal fusion treated with endoscopic spine surgery. Surg Technol Int 14:305, 2005; Denoziere
G et al: Biomechanical comparison between fusion of two vertebrae and implantation of an artificial
intervertebral disc. J Biomech 39:766, 2006; Evans CH et al: The 2003 Nicolas Andry Award. Orthopaedic gene
therapy. Clin Orthop Relat Res Dec:316, 2004; Inamasu J et al: Laparoscopic anterior lumbar interbody fusion: a
review of outcome studies. Minim Invasive Neurosurg 48:340, 2005; Isaacs RE et al: Minimally invasive microendoscopy-assisted
transforaminal lumbar interbody fusion with instrumentation. J Neurosurg Spine 3:98, 2005; Kroeber
MW et al: New in vivo animal model to create intervertebral disc degeneration and to investigate the effects of
therapeutic strategies to stimulate disc regeneration. Spine 27:2684, 2002; Levin R et al: Mini-open thoracoscopically
assisted thoracotomy versus video-assisted thoracoscopic surgery for anterior release in thoracic scoliosis and
kyphosis: a comparison of operative and radiographic results. Spine J 5:632, 2005; Liu J et al: Effect of the increase
in the height of lumbar disc space on facet joint articulation area in sagittal plane. Spine 31:E198, 2006; McAfee PC
et al: A prospective, randomized, multicenter Food and Drug Administration investigational device exemption study
of lumbar total disc replacement with the CHARITE artificial disc versus lumbar fusion: part II: evaluation of radiographic
outcomes and correlation of surgical technique accuracy with clinical outcomes. Spine 30:1576, 2005; Pickett
GE et al: Complications with cervical arthroplasty. J Neurosurg Spine 4:98, 2006; Powers CJ et al:
Placement of percutaneous pedicle screws without imaging guidance. Neurosurg Focus 20:E3, 2006; Puttlitz CM:
Intervertebral disc replacement maintains cervical spine kinetics. Spine 29:2809, 2004; Roughley PJ et al: The
role of proteoglycans in aging, degeneration and repair of the intervertebral disc. Biochem Soc Trans 30:869, 2002;
Roughley PJ: Biology of intervertebral disc aging and degeneration: involvement of the extracellular matrix. Spine
29:2691, 2004; Sekhon LH et al: Cervical arthroplasty after previous surgery: results of treating 24 discs in 15 patients.
J Neurosurg Spine 3:335, 2005; Sobajima S et al: Quantitative analysis of gene expression in a rabbit model
of intervertebral disc degeneration by real-time polymerase chain reaction. Spine J 5:14, 200.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. For this issue,
Dr. Mathews has disclosed that he is a consultant to Medtronic Sofamor Danek and K-2 Medical, and Dr. Dekutoski
is a consultant to Medtronic Sofamor Danek.
Drs. Zarembinski, Vaccaro, Mathews, Foley, and Dekutoski addressed the Fifth Annual Symposium on Current Concepts
in Spinal Disorders 2006, held February 3-4, 2006, in Las Vegas, Nevada and sponsored by Cedars-Sinai Medical
Center Institutes for Spinal Disorders. The Audio-Digest Foundation thanks the speakers and the Cedars-Sinai
Medical Center for their cooperation in the production of this program.
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