RESULTS: The 3-year survivorship was 94.5% at 3 years postoperatively

with 95% confidence interval from 0.820 to 1.070. There were no deaths,

no infections, and no instances of iatrogenic neurologic progression in

either the single-level or the multiple-level arthroplasty group. The self-

assessment outcomes instruments consistently showed more improvement

for the multilevel cases. The mean improvement in the NDI for the single

cases was 54.8% (620.9) versus the multilevel cases mean improvement in

NDI of 64.8% (633.7). The VAS, SF-36, Odoms, and TIGT were also

more improved for the multilevel versus the single-level group. The reop-

eration rates, adverse events, and incidence of complications were the

same between the single and multilevel arthroplasty groups.

CONCLUSIONS: This prospective report of cervical arthroplasty demon-

strates that each cervical vertebral level is biomechanically independent of

the adjacent level, whether it contains an arthoplasty or an unoperated in-

tervertebral disc. With the Porous Coated Motion cervical arthroplasty the

incidence of reoperation did not increase proportionately higher as the

number of cervical levels requiring instrumentation increased (2% Group

S and Group M). Even in three- and four-level arthroplasty the true benefits

of cervical disc replacement outcomes were demonstrated on functional

clinical outcomes (NDI, VAS, TGIT, Odoms, and SF-36).

FDA DEVICE/DRUG STATUS: PCM Cervical Disc Replacement:

Investigational/not approved.

CONFLICT OF INTEREST: Author (PM) Consultant: Cervitech;

Author (PM) Grant/Research Support: Cervitech; Author (PM) Speaker’s

Bureau Member: Cervitech; Author (PM) Stockholder: Cervitech.

doi: 10.1016/j.spinee.2006.06.271

P13. Clinical Use of Pedicle Nails With Bone Cement

for Osteoporotic Spine

Hitoshi Konishi, MD1, Yamana Keiya, MD2, Tanaka Masato, MD3; 1Seno

Hospital, Okayama, Japan; 2Okayama Citizens’ Hospital, Okayama,

Japan; 3Okayama Medical School, Okayama, Japan

BACKGROUND CONTEXT: Obtaining adequate purchase with stan-

dard pedicle screw techniques remains a challenge in poor quality bone.

Polymethylmethacrylate bone cement augmentation of the pedicle screw

can improve fixation strength compared with pedicle screw alone. The

pedicle nail system was designed for using bone cement.

PURPOSE: This report demonstrates the operative technique and clinical

results. The efficacy of pedicle nail with bone cement for osteoporotic

vertebral fracture is evaluated.

STUDY DESIGN/SETTING: The pedicle nail system consists of a cylin-

drical sheath and an internal screw. There are benefits to this system in that

the internal screw can be easily fixed to and removed from the sheath, and

the cement injection into the pedicle is safe because the cylindrical holes

that are made at the pedicles can be checked easily.

PATIENT SAMPLE: Thirty-five patients (11 male and 24 female), aged

65–88 years (average 72.6 years), with osteoporotic vertebral fractures and

delayed collapse of vertebrae were treated surgically using the pedicle nail

system with bone cement and a posterolateral bone graft. The collapsed

vertebrae were augmented with polymethylmethacrylate or hydroxyapatite

sticks. The osteoporotic vertebral fractures were at T9 in 2 patients, T10 in

2 patients, T11 in 4 patients, T12 in 11 patients, L1 in 7 patients, L2 in 3

patients, L3 in 4 patients, L4 in 2 patients. The preoperative neurological

status of 27 patients was incomplete paralysis due to spinal cord damage

caused by vertebral compression fracture, whereas 8 patients suffered pain

due to instability between vertebrae. Eight patients also had rheumatoid

arthritis, and 1 patient had L4 degenerative spondylolisthesis.

OUTCOME MEASURES: A retrospective clinical and radiographic re-

view was performed, and the state of the pedicle nails was evaluated by

dynamic radiographs and computed tomography scans.

METHODS: Clinical result, radiographs, and computed tomography

scans were reviewed at a mean follow-up period of 36 months (range

6–75 months).

RESULTS: Radiographic examination showed that successful spinal fu-

sion was obtained in all patients except one whose clamp and pedicle

nail unfastened in the recovery stage. There were no instances of nail

loosening or pullout of the nails. However, clear zones around nails were

seen in some cases. No breakage of pedicle nails was seen. Marked neu-

rologic recovery was obtained in 23 patients (92%) out of 25 after sur-

gery. All of the 8 patients who had complained of pain improved. In 3

patients, the pedicle screw systems except cylindrical sheaths were re-

moved without difficulty after completion of the posterolateral fusion.

The few complications consisted of extraosseous leakage and infection

in 1 patient each.

CONCLUSIONS: The pedicle nail system may be a viable clinical option

for achieving fixation in osteoporotic vertebral fractures.

FDA DEVICE/DRUG STATUS: Pedicle Nail: Not approved for this

indication.

CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2006.06.272

P14. Detecting Nonunion With Metallic Anterior Interbody Cages

Steven Glassman, MD1, Matthew F. Gornet, MD2, Brian Subach, MD3,

Thomas Schuler, MD4, James Schwender, MD5, Leah Carreon, MD6;1Spine Institute, Louisville, KY, USA; 2The Orthopedic Center of St. Louis,

St. Louis, MO, USA; 3The Virginia Spine Institute, Reston, VA, USA;4Virginia Spine Institute, Reston, VA, USA; 5Twin Cities Spine Center,

Minneapolis, MN, USA; 6Leatherman Spine Center, Louisville, KY, USA

BACKGROUND CONTEXT: Recent studies have demonstrated that CT

scan is superior to plain X-ray in evaluating anterior interbody fusion, par-

ticularly in the presence of metallic interbody devices. However, animal

studies suggest that CT scans may still over read the extent of fusion,

and the true accuracy of CT scan evaluation is unknown.

PURPOSE: To evaluate the accuracy of fusion assessment by CT scan, as

compared with surgical exploration, for patients treated by anterior inter-

body fusion with metallic cages.

STUDY DESIGN/SETTING: Multi-center retrospective analysis of

radiology reports and correlative surgical findings.

PATIENT SAMPLE: 75 patients, 106 surgical levels

OUTCOME MEASURES: Independent radiologists’ review of CT scan

findings vs. surgical findings at subsequent exploration.

METHODS: This is a retrospective review of 101 patients with prior an-

terior interbody fusion who underwent a revision for nonunion or adjacent

level pathology, which included exploration of the previously fused level.

Preoperative radiology reports including CT scan evaluation were

available for all cases, but 24 patients were excluded because the radiology

report made no mention of fusion status. For the remaining 75 patients

(106 surgical levels), CT scan report and surgical findings were compared.

Radiologist’s assessment was grouped as solid fusion, probable fusion, and

nonunion. Sensitivity, specificity, positive predictive values (PPV), and

negative predictive values (NPV) were generated for three scenarios in

which the ‘‘probable’’ readings were grouped as nonunion, grouped as

fusion, and excluded.

RESULTS: There were 38 males and 37 females with a mean age of 40.5

years (range 18–63). There were 34 smokers. Average time from index to

revision procedure was 22 months (range 3–73). The accuracy of CT scan

readings was generally poor regardless of how the data were analyzed.

When probable readings were grouped as nonunions, the sensitivity was

54% with a specificity of 70%. The probability that a patient has a non-

union given a reading of nonunion on the CT scan was only 46%

(PPV). The probability that a patient has a solid fusion given a reading

of solid fusion on the CT scan was only 53% (NPV). When probable read-

ings were grouped as fusions, the sensitivity was 45% with a specificity of

94%, a PPV of 26%, and an NPV of 73%. When probable readings were

excluded, the sensitivity was 43% with a specificity of 89%, a PPV of

33%, and an NPV of 67% (Table 1).

89SProceedings of the NASS 21st Annual Meetings / The Spine Journal 6 (2006) 1S–161S

Table 1

Surgical Finding

CT Reading Non-union Probable Soild Totals

No-union 25 0 3 28

Probable 14 0 7 21

Solid 33 0 24 57

Totals 72 0 34

CT Probable5CT Non-union

Surgical Finding

CT Reading Non-union Soild Totals

No-union 39 10 49

Solid 33 24 57

Totals 72 34 106

CT Probable5 CT Solid

Surgical Finding

CT Reading Non-union Soild Totals

No-union 25 3 28

Solid 47 31 78

Totals 72 34 106

CT Probable5Excluded

Surgical Finding

CT Reading Non-union Soild Totals

No-union 25 3 28

Solid 33 24 57

Totals 58 27 85

CONCLUSIONS: Assessment based upon surgical exploration demon-

strates that radiologists’ reading of fusion status is inaccurate for anterior

interbody fusion with metallic interbody devices. Even considering only

those cases which the radiologist identified as ‘‘definite fusion’’ or ‘‘non-

union’’, correlation with surgical findings was poor. This data suggests that

surgeons must rely upon clinical history and examination to identify

patients with nonunion after interbody fusion with metallic cages. It

remains undetermined whether spine surgeons, with or without clinical

input, would generate a more accurate preoperative assessment than inde-

pendent radiologists.

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

any applicable devices or drugs.

CONFLICT OF INTEREST: Author (SG) Consultant: Medtronic

Sofamor Danek; Author (SG) Grant/Research Support: Medtronic Sofamor

Danek; Author (SG) Royalties: Medtronic Sofamor Danek.

doi: 10.1016/j.spinee.2006.06.273

P15. Economics of Infuse Bone Graft for Posterolateral Fusions

Steven Glassman, MD1, Mitchell Campbell, MD2, Leah Carreon, MD2,

John Johnson, MD2, Rolando Puno, MD2, Mladen Djurasovic, MD3,

John Dimar, II, MD1; 1University of Louisville, Louisville, KY, USA;2Leatherman Spine Center, Louisville, KY, USA; 3Louisville, KY, USA

BACKGROUND CONTEXT: Infuse Bone Graft is approved as an ICBG

substitute for single-level anterior interbody fusion, but is also used in pos-

terior lumbar fusion cases. Initial reports support the efficacy of Infuse for

both posterolateral fusion and TLIF. However, the economic implications

of using Infuse instead of ICBG remain a critical unresolved issue.

PURPOSE: To evaluate the perioperative and early postoperative cost of

Infuse vs. ICBG in posterolateral lumbar spine fusion.

STUDY DESIGN/SETTING: Prospective randomized nonblinded clini-

cal trial of posterolateral fusion using Infuse vs. ICBG in patients older

than 60 years of age.

PATIENT SAMPLE: Seventy-nine patients with complete perioperative

and early postoperative (0–3 month) economic data.

OUTCOME MEASURES: Directly recorded cost accounting for all

in-patient and out-patient services, tracked by a dedicated hospital coder.

METHODS: Patients over 60 years old requiring decompression and pos-

terolateral lumbar fusions were randomized to Infuse (n537) or ICBG

(n542) groups. All other treatment variables were performed according

to the surgeon’s standard perioperative protocol. All patients were fol-

lowed by a dedicated hospital coder and a dedicated research nurse. Costs

associated with in-patient hospital care, in-patient physician services, post-

operative rehab services, and all postoperative health-care system encoun-

ters were recorded. Events occurring at outlying facilities or events for

which direct cost data could not be ascertained were assigned cost based

on the Medicare fee schedule.

RESULTS: The 37 Infuse patients included 13 males and 24 females, with

a mean preoperative SF-36 PCS of 27.2 and mean preoperative ODI of

51.1. The 42 ICBG patients included 16 males and 26 females, with a mean

preoperative SF-36 PCS of 29.1 and mean preoperative ODI of 47.7. Mean

age was 69 years in both groups. The number of levels fused was similar in

both groups. There were no significant demographic differences between

the groups. Surgical variables were also statistically equivalent for both In-

fuse and ICBG groups, and included mean levels fused (2.03 vs. 2.02),

mean OR time (222 min vs. 237 min), and mean EBL (693 cc vs. 734

cc). ICBG patients had a longer hospital stay (6.02 vs. 5.03 days,

p5.023), and greater ICU and TCU days. ICBG patients more frequently

required inpatient rehab (76% vs. 59%). Inpatient cost for hospital services

averaged $24,971 in the Infuse group and $21,342 in the ICBG group. Av-

erage cost for in-patient physician services was $5,154 in the Infuse group

and $5,289 in ICBG patients. Outpatient services, including rehabilitation

costs, averaged $5,085 for Infuse patients and $8,096 for the ICBG group.

Total mean cost was $35,235 for the Infuse group and $34,772 for the

ICBG group.

CONCLUSIONS: The perioperative economic impact of Infuse Bone

Graft in posterolateral fusion surgery is significantly different than the

$5,000 unit cost. Actual mean hospital cost was approximately $3,500

greater, but mean out-patient cost was approximately $3,000 less in the In-

fuse group. The out-patient cost differential was based primarily on rehab

expenses. This data suggests that while the hospital absorbs a greater initial

cost, the insurer, particularly in a DRG model, experiences an initial cost

decrease.

FDA DEVICE/DRUG STATUS: Infuse Bone Graft: Not approved for this

indication; Pedicle Screws: Approved for this indication.

CONFLICT OF INTEREST: Authors (SG, MC, JJ, RP, MD, JDI)

Consultant: Medtronic Sofamor Danek; Authors (SG, MC, JJ, RP, MD,

JDI) Grant/Research Support: Medtronic Sofamor Danek; Authors (SG,

MC, JJ, RP, MD, JDI) Royalties: Medtronic Sofamor Danek.

doi: 10.1016/j.spinee.2006.06.274

P16. Incidence of Simultaneous Epidural and Vascular Injection

During Cervical Transforaminal Epidural Injection

Matthew Smuck, MD, Brian Fuller, MD; University of Michigan, Ann

Arbor, MI, USA

BACKGROUND CONTEXT: Rare but serious morbidity and mortality

has been reported after cervical transforaminal epidural injections, and

accidental intravascular injection is often cited as the cause. Due to the

fleeting appearance of vascular contrast patterns, the use of intermittent

fluoroscopy during contrast injection can miss inadvertent vascular injec-

tion. This is especially true in the setting of a concurrent epidurogram.

Routine use of real-time dynamic fluoroscopy during contrast injection

reveals the intermittant occurrence of simultaneous epidural and vascular

injections; however, the incidence has never been reported.

90S Proceedings of the NASS 21st Annual Meetings / The Spine Journal 6 (2006) 1S–161S