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.