associated with aging may or may not be altered with arthroplasty, some

have hypothesized that ACDF accelerates the degenerative cascade.

PURPOSE: The purpose of this study was to perform a retrospective

analysis of anterior osteophyte area and protrusion in degenerative cervical

patients treated with an Affinity Anterior Cervical Cage System, a Bryan

Cervical Disc prosthesis, or a Cornerstone-SR Allograft Implant.

STUDY DESIGN/SETTING: The study was a retrospective radiographic

analysis of digitized films.

PATIENT SAMPLE: Radiographic history from 139 patients with the

Affinity cage, 64 patients with the Bryan disc, and 15 patients with the

Cornerstone allograft were reviewed.

OUTCOME MEASURES: Anterior osteophyte protrusion and anterior

osteophyte area were quantified using digital techniques for both the ceph-

alad and caudad vertebral bodies at the index level, the level superior to the

index level, and the level inferior to the index level.

METHODS: Preoperative, 12-month, and 24-month lateral films were ret-

rospectively digitized for the 218 patients studied. In total, 2616 vertebrae

were analyzed on 654 digitized radiographs. Anterior osteophyte area and

protrusion were quantified for both the inferior and superior aspects of the

vertebrae at the operative disc space and the disc spaces above and below.

Data were compared using ANOVA with Bonferroni’s adjustment for

multiple comparisons.

RESULTS: The changes in total osteophyte area at the index disc space

from the preoperative time point to both the 12- and 24-month time points

were statistically less for Bryan than Affinity and Cornerstone. Bryan had

less new osteophyte area than Cornerstone on the inferior vertebra at the

disc space above the operative level over the period from 0 to 12 months.

Bryan had less new osteophyte protrusion than Affinity on the inferior ver-

tebra at the disc space below the operative level over the period from 0 to

24 months.

CONCLUSIONS: Osteophyte formation at or adjacent to a Bryan disc

was either statistically similar or less than the osteophyte formation at or

adjacent to Affinity or Cornerstone SR ACDF devices. This result suggests

that implantation of the Bryan disc results in a reduction in the rate of

adjacent level degeneration compared with ACDF.

FDA DEVICE/DRUG STATUS: Affinity Anterior Cervical Cage System:

Approved for this indication; Bryan Cervical Disc prosthesis: Investiga-

tional/Not approved; Cornerstone-SR Allograft Implant: Approved for this

indication.

CONFLICT OF INTEREST: Authors (VT, SP) Consultant: Medtronic

Sofamor Danek; Author (JR) Stockholder: Medtronic; Author (JR)

Employee: Medtronic.

doi: 10.1016/j.spinee.2006.06.218

P73. Surgical Decompression With Radiotherapy versus

Radiotherapy Alone in the Palliative Care of Patients with

Metastatic Spinal Cord Compression: An Economic Evaluation

Using Ontario Data

Julio Furlan, MD, MBA, PhD1, Kelvin Chan, MD2, Guillermo Sandoval,

MBA3, Kenneth Lam, BA, MA, MPA3, Christopher Klinger, MPA3,

Roy Patchell, MD4, Audrey Laporte, PhD3, Michael Fehlings, MD, PhD3;1Toronto Western Hospital, University Health Network and University of

Toronto, Toronto, Ontario, Canada; 2Grand River Regional Cancer Center,

Kitchener, Ontario, Canada; 3University of Toronto, Toronto, Ontario,

Canada; 4University of Kentucky, Lexington, KY, USA

BACKGROUND CONTEXT: For selected patients with metastatic

epidural spinal cord compression (MESCC), direct decompressive surgery

(Sx) followed by radiotherapy (RT) has recently been shown to be superior

to radiotherapy alone with respect to the ability to ambulate and overall

survival. In addition to the paucity of high-quality cost-utility analyses

in orthopedic surgery, the economic impact of adopting Sx þ RT strategy

has not been assessed previously.

PURPOSE: This study, for the first time, carries out an economic evalu-

ation comparing Sx þ RT strategy with RT-only approach.

STUDY DESIGN/SETTING: Cost-effectiveness and cost-utility

analyses.

PATIENT SAMPLE: This study was primarily based on the results from

a randomized controlled trial. Additional data for the analysis were ob-

tained from a cohort of patients who were admitted to a university-teaching

hospital in Toronto from January 2001 to July 2005.

OUTCOME MEASURES: Quality-adjusted life years (QALYs) gained

and incremental cost-effectiveness ratio (ICER) are the primary outcome

measures.

METHODS: An analytic decision model was constructed based on the

results from Patchell et al. The perspective of the public health care insurer

was adopted for the analysis. Costing was carried out using Ontario data

for the following items: surgery, radiotherapy, hospitalization, home care

services, palliative hospice, and medications. Utilities were obtained from

the Harvard University Catalogue of preference score and the Health

Outcomes Data Repository Data – Health Utility list. A probabilistic

sensitivity analysis with Monte-Carlo simulation was performed.

RESULTS: When comparing Sx þ RT strategy with RT-only strategy, the

ICER is CAD$ 43,796 per QALY gained. The cost-utility of Sx þ RT

strategy is CAD$ 509,084 per QALY and that of RT-only strategy is

CAD$ 2,381,246 per QALY. The cost of surgery is partially offset by

the decreased cost of hospice palliative care because more patients remain

ambulatory and stay at home. Monte-Carlo simulation showed that there is

a 25% chance that Sx þ RT strategy may dominate RT-only approach. The

results are sensitive but generally robust to changes in assumptions about

the costs of surgery, home care, and palliative hospice care.

CONCLUSIONS: Our results suggest that a change in the palliative treat-

ment protocols for MSCC patients towards Sx þ RT strategy is more likely

to increase health-care costs. However, the gain in terms of patients’ qual-

ity of life for such a dreaded clinical condition is relatively significant and

should be taken into consideration by health-care policymakers.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

CONFLICT OF INTEREST: Author (JF) Grant/Research Support: Law-

son Fellow-Neurology from The Toronto General&Western Hospital Foun-

dation and the Henry A. Beatty Scholarship; Author (MF) Grant/Research

Support: Krembil Chair in Neural Repair and Regeneration.

doi: 10.1016/j.spinee.2006.06.219

P74. Spinous Process Splitting Midline LaminectomydA Novel

Minimally Invasive Technique for Decompression of the Lumbar

Spine: A Human Cadaver Study

Jon Kimball, MD, Michael Mac Millan, MD; University of Florida,

Gainesville, FL, USA

BACKGROUND CONTEXT: Minimally invasive surgery has become an

increasingly accepted and important means of spine surgery for reducing

iatrogenic tissue trauma, patient morbidity, and delayed sequelae related

to traditional techniques. To date, a spinous process splitting midline

minimally invasive technique has not been used to decompress the lumbar

spinal canal.

PURPOSE: The purpose of the study was to determine the feasibility of

using a novel midline laminectomy technique to treat spinal stenosis.

STUDY DESIGN/SETTING: The design of the study was to evaluate the

technical feasibility of decompression of lumbar stenosis via a novel

minimally invasive midline spinous process splitting approach in a human

cadaver model.

PATIENT SAMPLE: Four embalmed human cadavers were studied.

OUTCOME MEASURES: The change in cross-sectional area of the spi-

nal canal after decompression using a novel technique.

METHODS: In four human cadavers, stenotic lumbar levels were identi-

fied by computerized tomography (CT). The decompression was per-

formed by using a high-speed drill to divide the spinous process through

its midline down to the level of the lamina, then detaching each half of

the spinous process and retracting it laterally. This allowed visualization

118S Proceedings of the NASS 21st Annual Meetings / The Spine Journal 6 (2006) 1S–161S

of the lamina for decompression. The procedure was performed once at

each respective level, and CT was then repeated to establish and measure

the extent of decompression of the spinal canal.

RESULTS: The procedure was successfully performed at every stenotic

lumbar level. Satisfactory decompression was achieved using this novel

approach and resulted in restoration of normal canal diameters. The aver-

age cross-sectional area was increased from 128 mm2 (637 mm2) to 448

mm2 (621 mm2) after decompression. Canal decompression averaged

250% (639%).

CONCLUSIONS: Minimally invasive spinous process splitting midline

laminectomy can be used to decompress the spinal canal effectively and

may prove to be beneficial in decreasing the complications and morbidity

of standard and other minimally invasive treatments for lumbar stenosis.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2006.06.220

P75. Lumbar Intervertebral Disc Stabilization (IDS): A Stand-Alone

Lumbar Fusion Technique Using Unilateral Disc Device

Madhavan Pisharodi, MD, Amayur Chandran, PhD; Brownsville Pain

Research Center, Brownsville, TX, USA

BACKGROUND CONTEXT: A good ‘stand-alone’ stabilization and fu-

sion technique that can be performed posteriorly has been eluding spine

surgeons. Such a stabilization technique requires a disc device that con-

forms to the biconvex shape of the disc space to ensure optimal stabiliza-

tion and should preserve most of the anatomical structures that act

synergistically for stabilization, so that the additional instrumentation

can be avoided.

PURPOSE: To determine the safety and efficacy of a new lumbar interver-

tebral disc device (Pisharodi Device-PD) for disc stabilization and to facil-

itate fusion, a feasibility study followed by a prospective randomized

multi-center study was conducted by comparing the success rate between

the new implant and Ray threaded fusion (RTF) cages.

STUDY DESIGN/SETTING: Lumbar intervertebral disc stabilization

(LIDS) procedure involving PD was conducted in two hospitals during

the feasibility study and in five investigational sites during the multi-center

clinical trial under the supervision of Investigational Review Boards (IRB),

following a protocol approved by the Food and Drug Administration

(FDA).

PATIENT SAMPLE: The feasibility study involved 25 patients with low

back pain due to disc herniation and a multi-center study involving so far

96 patients (aged 18–59 years) with low back pain due to degenerative disc

disease.

OUTCOME MEASURES: The patients had follow-up evaluations at 3, 6,

12, and 24 months after the surgery; this included clinical (pain level, work

status, muscle strength, and reflexes) radiological (flexion/extension, disc

height, implant status including migration), and electrodiagnostic studies.

Quality of life was assessed by SF-12 health survey and pain level by

Oswestry pain questionnaire.

METHODS: PD has two parts, a core piece having a biconvex shape and

an end-cap that slides on to the biconvex piece along the sides, both being

secured by a screw. After simple discectomy, the disc space was filled with

autograft taken from the iliac crest. The biconvex piece of PD was inserted

horizontally and rotated 90 degrees inside the disc space, the end-cap slid

along and fastened with the biconvex piece with the screw to form a

compact unit. PD is implanted only unilaterally.

RESULTS: Follow-up evaluations 3 months after the surgery showed ra-

diological evidence of 100% fusion and less than 3 mm translation during

flexion/extension in all the patients. The disc height was maintained with-

out any significant subsidence. There was a significant improvement in the

work status and number of patients taking pain medications at 3-month fol-

low-up interval after the surgery. Posterior migration of the implant was

observed in 8 (out of 122) patients, but there was no evidence of any

post-surgical neurological deficit in any of the patients. Twenty-five pa-

tients during the feasibility study and 57 patients during the multi-center

clinical trial had passed the 24-month follow-up interval. Responses to

the Oswestry pain questionnaire showed significant (more than 15%) im-

provement in 20 patients, and the SF-12 health survey showed satisfactory

level of quality of life in 38 patients during the multi-center study.

CONCLUSIONS: PD is assembled inside the disc space and implanted

unilaterally to reduce the tissue loss and to give maximum graft to bone

contact for optimal fusion. LIDS procedure using PD is a simple, safe

and reliable surgical technique that acts as a stand-alone stabilization

procedure for lumbar fusion.

FDA DEVICE/DRUG STATUS: Pisharodi Device: Investigational/not

approved.

CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2006.06.221

P76. Bioactive Titanium Calcium Phosphate Coating for Disc

ArthroplastydAnalysis of 68 Vertebral End plates after 6 to 33

Months Implantation

Bryan Cunningham, MSc1, Nianbin Hu, MD1, Paul McAfee, MD2,

Helen Beatson, BS1, Justin Tortolani, MD3, Luis Pimenta, MD4; 1Union

Memorial Hospital, Baltimore, MD, USA; 2Spine and Scoliosis Center,

Towson, MD, USA; 3MD, USA; 4Brazil

BACKGROUND CONTEXT: N/A.

PURPOSE: This is the largest analysis to date of any retrieved porous

ingrowth disc replacement prostheses. In distinction to prior reports of

retrieved implants which were conducted like ‘‘airplane crash’’ type pseu-

doanalyses, in this series the position of the components was known in vivo

before implant removal. The digitized radiographs were used to determine

if the components were in ideal, suboptimal, or poor position. There were

30 cervical disc replacements and 38 lumbar disc replacements which

comprised the basis of this analysis.

STUDY DESIGN/SETTING: N/A.

PATIENT SAMPLE: N/A.

OUTCOME MEASURES: N/A.

METHODS: Quantitative histomorphometry, microradiography, and his-

tology were performed on all 68 vertebral end plates. Scanning electron

microscopy was performed on 10. All 24 caprine model, 34 nonhuman

primates, and 10 human explants with titanium calcium phosphate porous

ingrowth surface were manufactured by the same vendor, D.O.T., which

provides the same porous ingrowth coating for several FDA-approved total

hip replacements. Group I – Ideal placement, defined as Charite or PCM

Artificial Disc replacement within 3 mm of exact central axis in both

the coronal planes and mid-sagittal planes (2 mm posterior to the midpoint

of the vertebral body in the sagittal plane for Charite only). The end plates

of the prosthesis also had to be within 5 degrees of angulation of the bony

end plate or within 5 degrees of angulation of the perpendicular axis of the

vertebral body. Group II–Suboptimal placement, defined as Charite or

PCM Artificial Disc placement 3 mm to 5 mm from exact central place-

ment in at least one axis. In addition, the prosthetic end plate had to be

from 5 degrees to 10 degrees of perpendicular vertebral body orientation.

Group III–Poor placement, defined as greater than 5 mm from exact central

placement in at least one axis, or the end plate was greater than 10 degrees

off angle. Three separate observers judged the measurements of axes and

made a determination of prosthesis placement after correction for magni-

fication error.

RESULTS: The mean length of time in biologic conditions to monitor re-

absorption and incorporation of the ingrowth surface was 10.5 months

(range 6 to 33 months). This is the first study finding a correlation between

the position of the components and the amount of successful bony in-

growth. A representative group was Ideal 50.9613% ingrowth, Suboptimal

placement, 49.3618% ingrowth, and Poor, 33.0629.2% ingrowth. There

was a trend, but it was not statistically significant (F51.78, p5.186).

The mean ingrowth of prostheses in poor and suboptimal position (defined

119SProceedings of the NASS 21st Annual Meetings / The Spine Journal 6 (2006) 1S–161S