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5SProceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S
9. Oxiplex Reduces the Incidence of Back Pain, Leg Pain and
Associated Symptoms Six Months Following Single-Level Lumbar
Laminectomy for Removal of a Herniated Disc
Jeffrey Wang, MD1, Paul Arnold, MD2; 1University of California, Los
Angeles, Santa Monica, CA, USA; 2University of Kansas, Kansas City, KS,
USA
BACKGROUND CONTEXT: Oxiplex gel (carboxymethylcellulose,
polyethylene oxide and calcium) was developed to coat and protect nerve
roots for reduction of pain and symptoms following lumbar disc surgery.
PURPOSE: To evaluate the safety and effectiveness of Oxiplex gel
for reduction of pain and associated symptoms following lumbar disc
surgery.
STUDY DESIGN/ SETTING: The study was a randomized, third-party
blinded, multicenter, pivotal clinical trial to evaluate the safety and effec-
tiveness of Oxiplex gel to reduce postoperative back and leg pain as well as
related symptoms following surgery for removal of a herniated lumber disc
at L4-L5 or L5-S1.
PATIENT SAMPLE: Patients undergoing single-level lumbar laminec-
tomy or laminotomy, and a discectomy randomized to receive either sur-
gery plus Oxiplex (n5177) or surgery alone (n5175).
OUTCOME MEASURES: At baseline and following surgery at 1, 3,
and 6 months patients were evaluated using 1) quality of life measures
(Lumbar Spine Outcomes Questionnaire: LSOQ, BenDebba et al., Spine
J. 7:118–132), and 2) clinical evaluations were performed at 1 and 6
months.
METHODS: Patients undergoing single-level lumbar laminectomy, lami-
notomy, or discectomy were ineroperatively randomized to receive either
surgery plus Oxiplex or surgery alone. Patients were assessed 1, 3 and 6
months following surgery using 1) the LSOQ), and 2) clinical evaluations.
Safety was evaluated by analyzing adverse events and clinical symptoms.
Effectiveness was evaluated by scoring the LSOQ to produce composite
scores for leg pain, back pain, and patient satisfaction.
RESULTS: Baseline demographics, surgical procedures, LSOQ scores
and clinical evaluations were balanced between Oxiplex (N5177) and
surgery-only (N5175) groups. All subjects did well following surgery.
There were no cases of CSF leaks in the Oxiplex-treated group and no
differences in laboratory values or vital signs. There were no differences
in adverse events, laboratory values or physical findings between Oxiplex-
treated patients and controls. Oxiplex patients in the challenging patient
population having severe back pain at baseline showed greater reductions
in pain and symptoms from baseline across all LSOQ variables compared
to surgery-only controls. In that population, there was a statistically sig-
nificant reduction of back pain [P50.013] and leg pain [P50.012] in
the Oxiplex group compared to controls at 6 months following surgery.
More Oxiplex patients were satisfied with the outcome of their surgical
treatment than control patients (P50.045). Fewer patients in the Oxiplex
group had abnormal musculoskeletal physical exams at 6 months com-
pared to controls. Patients in the Oxiplex group had less hypoaesthesias,
paraesthesias, and sensory loss compared to controls. Patients in the Ox-
iplex group had fewer re-operations during the 6-month follow-up than
controls (1 vs. 6).
CONCLUSIONS: Taken together, these data demonstrate a consistent
clinically significant improvement in outcomes resulting from the use of
Oxiplex gel in lumbar spine surgery.
FDA DEVICE/DRUG STATUS: Oxiplex: Investigational/Not approved.
doi:10.1016/j.spinee.2008.06.011
10. Embryonic Stem Cells Used for Disc Regeneration in an In Vivo
Model of Disc Degeneration
Ramiro Perez De La Torre, MD1, Hormoz Sheikh, MD2, Mick Perez-Cruet,
MD2, Chistopher Fecek, MSN, MS3, Rasul Chaudhry, PhD4,
David Svinarich, PhD5; 1Oakland University, Troy, MI, USA; 2Southfield,
MI, USA; 3Department of Biological Sciences, Rochester, MI, USA;
4Oakland University, Department of Biological Sciences, Rochester, MI,
USA; 5Providence Hospital and Medical Center, Detroit, MI, USA
BACKGROUND CONTEXT: There is currently no therapy to repair or
restore degenerated intervertebral discs. Embryonic stem (ES) cells can
potentially grow indefinitely in vitro and differentiate into a variety of cell
types. (1) Therefore, ES cells provide an attractive alternative to com-
monly used sources for deriving cells of various lineages for therapeutic
purposes including cells capable of potentially producing nucleus pulpo-
sus. (2) The notochordal cell is felt to be the origin of the intervertebral
disc. As this cell is replaced by terminally differentiated chondrocytes, disc
degeneration begins, most likely as a result of reduced proteoglycan pro-
duction and subsequent loss of water content of the intervertebral disc.
PURPOSE: To report on the potential of murine embryonic stem cells and
their capabilities to differentiate into notochordal cells in an in vivo rabbit
model of disc degeneration
STUDY DESIGN/ SETTING: Basis science experiment
METHODS: A novel In-vivo animal model of disc degeneration was
developed by needle puncture of healthy discs in 16 New Zealand White
rabbits. Rabbits were subjected to magnetic resonance imaging (MRI)
pre-operatively and at 2, 4, and 8 weeks post-operatively. Once radiograph-
ically confirmed, degenerated disc levels where injected with pre-treated
murine embryonic stem cells (ESCs) labeled with a mutant green fluores-
cent protein (GFP). These cells were pre-treated to differentiate along
a chondrocyte cell line. At 8 weeks intervertebral discs were harvested
and analysed with hematoxylin and eosin (H&E) staining, confocal fluo-
rescent microscopy and immuno-histochemical analysis. Three interverte-
bral groups were analyzed: 1. control non-punctured discs (Group A, n532
disc), 2. experimental control punctured disc (Group B, n516 disc), 3. ex-
perimental punctured disc followed by implantation of ESCs (Group C,
n516).
RESULTS: MRI imaging confirmed reproducible intervertebral disc de-
generation at needle punctured segments starting at approximately 2
weeks. Post-mortem histologic analysis of group A intervertebral disc
showed aged chondrocytes and almost complete disappearance of noto-
chordal cells. Group B discs displayed intact annulus fibrosus and gener-
alized disorganization of nucleus pulposus with increased bone
formation . Group C discs showed viable new cartilage forming as well
as notochordal cell growth. Fluorescent analysis was negative for groups
A and B but revealed viable chondrocytes within experimental group C
discs implanted with ESCs. Of note, no inflammatory response as evidence
of cell mediated immune response was noted in Group C discs.
CONCLUSIONS: This study illustrates a novel reproducible model for
the study of disc degeneration as well as disc regeneration using ESCs.
New notochordal cell populations were seen in ES cell injected degener-
ated discs. The lack of immune response to xenograft implanted mouse
cells in an immune competent rabbit model points to an immunologic
sanctuary within the intervertebral disc.
FDA DEVICE/DRUG STATUS: This abstract does not discuss or include
any applicable devices or drugs.
doi:10.1016/j.spinee.2008.06.012
11. Twenty-four Month Results from a Prospective Randomized
Controlled IDE Study of the DYNESYS Dynamic Stabilization
System
Reginald Davis, MD1, Rick Delamarter, MD2, Jeffrey Wingate, MD3,
John Sherman, MD4, James Maxwell, MD5, William Welch, MD, FACS,
FICS6; 1Greater Baltimore Medical Center, Towson, MD, USA; 2Santa
Monica, CA, USA; 3Michigan Spine Institute, Waterford, MI, USA; 4Edina,
MN, USA; 5Scottsdale Spice Care, Scottsdale, AZ, USA; 6Pittsburgh, PA,
USA
BACKGROUND CONTEXT: Patients with radiculopathy due to spondy-
lolisthesis or stenosing lesions are typically treated with decompression
6S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S
and spinal fusion. A posterior stabilization system has been developed to
stabilize without the need for fusion. The results of a prospective, random-
ized IDE study examining dynamic stabilization with the Dynesys Dy-
namic Stabilization System are being reported.
PURPOSE: The purpose of this study is to compare clinical outcomes fol-
lowing posterior dynamic stabilization or instrumented, posterior lateral
fusion.
STUDY DESIGN/ SETTING: Prospective, randomized, controlled,
multi-center clinical trial
PATIENT SAMPLE: This study reports the outcomes of 253 patients fol-
lowing dynamic stabilization (DS) and 114 patients treated with posterio-
lateral fusion (PLF) at 28 centers.
OUTCOME MEASURES: Lower limb and back pain were evaluated us-
ing 100mm visual analog scales. The Oswestry Disability Index (ODI) was
used to evaluate patient functioning and the Short Form-12 questionnaire
was used to assess the participants’ general health. Overall patient satisfac-
tion was reported, and a radiographic analysis was included in this study.
METHODS: Patients enrolled in this study exhibited lateral or central spi-
nal stenosis, degenerative spondylolisthesis or retrolisthesis (¡UGrade I),
and were appropriate for instrumented fusion at 1–2 contiguous spinal
levels (L1-S1). Participants randomly received treatment with DS or instru-
mented PLF (2:1 ratio) and were evaluated pre-operatively and post-oper-
atively at 3-weeks, 3-, 6-, 12-, and 24-months.
RESULTS: At 24M, the DS cohort reported 54.7mm improvement in leg
pain scores, a reduction in ODI scores of 29.7, 26.0mm improvement in
back pain, and 92% of subjects either improved or maintained their level
of neurological success compared to pre-op assessment. In the PLF cohort,
leg pain scores improved by 47.3mm, ODI scores were reduced by 24.3,
back pain scores improved by 20.0mm, and 84% of subjects reported im-
proved or maintained neurological success compared to pre-op evaluation.
Improvement reported in leg pain scores at 24M was significantly different
between the study groups (p!0.05). Similarly, back pain scores reported at
24-months were statistically significant between groups (p!0.05). Addi-
tionally, 24M data shows the SF-12 Physical Component increased signif-
icantly from 27.5 (pre-op) to 41.0 (24M) in the DS group and 27.4 to 37.2
in the PLF group (p!0.05). In the DS cohort, 28 subjects (11.1%) required
a revision surgery; 11 revision surgeries were reported in the PLF cohort
(9.6%). Ratio is consistent with the 2:1 randomization scheme. Addition-
ally, 39 intra-operative adverse events were reported in the DS group; 34/
39 were dural tears. The screw loosening rate for the DS cohort was 0.88%
(11/1244) and 1.65% (9/546) for the PLF group. The DS cohort reported
a screw breakage rate of 0.16% (2/1244). Radiographic analysis of DS co-
hort shows no instances of kyphotic events and no instances of spontane-
ous fusion.
CONCLUSIONS: Clinical outcomes from an IDE clinical trial are re-
ported. At 24M, the subjects implanted with the Dynesys Dynamic Stabi-
lization System show an improvement in ODI, Neurological Success, and
SF-12 scores and a significant improvement in leg pain, back pain, and SF-
12 Physical Component scores. Radiographic analysis shows screw loosen-
ing and screw breakage rates of !1% and no instances of kyphotic events
or spontaneous fusion were reported.
FDA DEVICE/DRUG STATUS: Dynesys Dynamic Stabilization System:
Investigational/Not approved.
doi:10.1016/j.spinee.2008.06.013
12. Complications and Adverse Events Observed When Using
DYNESYS as a Dynamic Stabilization Device
Mohammed Majd, MD1, Richard Kube, II, MD2, Richard T. Holt, MD1;1Spine Surgery, PSC, Louisville, KY, USA; 2Peoria, IL, USA
BACKGROUND CONTEXT: Dynesys consists of titanium hydroxyap-
petite (HA) coated pedicle screws, flexible cord and polycarbonaturethane
spacer and has been used off-label as a dynamic stabilizer of the lumbar
spine. Biomechanical studies reveal motion at the level of Dynesys
implantation. The theorized benefit of motion is improved outcomes, fewer
returns to the operating room and decreased arthritic change at adjacent
motion segments. To this point, no one has published postoperative com-
plications observed when using Dynesys off-label as a motion preservation
device. This study reviews the complications and adverse events that oc-
curred in our series of 92 patients in the first 2 years following surgery.
PURPOSE: We report complications and adverse events observed in our
series of 92 patients with Dynesys implantation for dynamic stabilization.
STUDY DESIGN/ SETTING: Ninety-two patients underwent implanta-
tion of 538 screws from March, 2005 to March, 2007. Patients had 6 to
24 months of follow-up and were seen in the office at 2, 4, 6, 12 and 24
months after surgery. At each visit, AP/Lat lumbar radiographs were taken.
Patients with suspicious radiographic findings or clinical symptoms under-
went further imaging studies such as MRI, myelogram/CT or discogram.
Further treatment was rendered as needed.
PATIENT SAMPLE: 92 consecutive patients with Dynesys implantation
were followed for 6–24 months.
METHODS: See above
RESULTS: 18 of the 92 patients (20%) had events leading to revision sur-
gery in 15 patients (16%). Seven complications (39% of complications)
were screw loosening seen on x-ray (screw halo sign) which was confirmed
with a CT scan. All loose screws were non-HA coated and located at the
cephalad or caudal aspect of the construct. There was also association of
loosening with thoracolumbar implantation, T score!�1 and implantation
into motion segments with O50% disc height loss. Four of seven patients
with screw loosening were revised with larger diameter HA coated screws.
All four demonstrated significant clinical improvement. One patient devel-
oped a screw fracture and required revision. One patient had an asymptom-
atic pars fracture. Two patients developed spinal stenosis cephalad to the
level of implantation. Both patients had a normal spinal canal prior to
the index procedure and both underwent a decompression and extension
of the construct. Eight patients (44% of complications) underwent revi-
sions and conversions to fusion due to continued low back and leg pain.
Two of these patients and two of the seven patients with screw loosening
(4% of total patients and 22% of total complications) had developed a deep
wound infection and underwent irrigation and debridement with implant
removal and conversion to fusion.
CONCLUSIONS: Posterior dynamic stabilization using the Dynesys sys-
tem is an effective treatment for multiple degenerative lumbar pathologies.
There are a significant number of complications (20% of patients) seen in
the 6–24 months following surgery. About 40% of these complications
were related to screw loosening. After correcting for loosening, the com-
plication rate is about 12% overall which is similar to that of fusion. To
decrease the complication rate associated with loosening, we recommend:
1) use HA coated screws; 2) avoid implantation at the thoracolumbar junc-
tion; 3) avoid implantation in patients with T-score !�1; 4) avoid implan-
tation if discs are significantly collapsed (height!50% of normal adjacent
disc).
FDA DEVICE/DRUG STATUS: Dynesys Dynamic Stabilization System:
Investigational/Not approved.
doi:10.1016/j.spinee.2008.06.014
13. Radiographic Disc Changes in the Bridged and Adjacent
Segments Following DYNESYS Dynamic Stabilization
Alexandru Mertic, Medic, MSC, Abhishek Kumar, MBBS, MRCS,
James Beastall, MBBS, MRCS, Agata Pawulska, MBBS,
Anjali Nandakumar, MBBS, Francis W. Smith, MD, FRCS, FRCR,
Douglas Wardlaw, FRCS, ChM; Centre for Spinal Research, Woodend
Hospital, Aberdeen, Scotland, United Kingdom
BACKGROUND CONTEXT: Adjacent segment disc degeneration is one of
the potential complications of fusion surgery. It has been proposed that non
fusion motion preservation surgery may prevent accelerated adjacent segment
degeneration due to the protective effect of persisting segmental motion.