125SProceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

Orientation of the FJ has been considered as one of the determining factors

of these biomechanical functions. Relationship between the FJ orientation

and low back pain (LBP) and changes in FJ orientation with age have been

are not clearly understood.

PURPOSE: To measure the three-dimensional (3D) FJ orientation in

a broad patient sample comprised of various ages, and existence/absence

of pain-symptoms using a novel CT-based in vivo measuring technique.

STUDY DESIGN/ SETTING: In vivo, non-invasive CT-based imaging

technique.

PATIENT SAMPLE: Ninety subjects (21 to 59 years old) including

non-symptomatic (n557) and symptomatic (n533) subjects (IRB

approved).

OUTCOME MEASURES: 3D FJ orientation of superior and inferior FJ

surfaces. Comparison between symptomatic vs. non-symptomatic groups

by unpaired t-tests. Level and age effects analyses by ANOVA and a Fisher

post-hoc test.

METHODS: The subjects were grouped by age and presence/absence of

chronic LBP. CT images from L1 to S1 in a supine position were used. 3D

FJ surface models consisting of over 200 polygons were created from CT

images for both superior and inferior FJ surfaces. A mean normal vector

was determined for each FJ surface by averaging all normal vectors calcu-

lated in each polygon. 3D orientation of each FJ surface plane was deter-

mined by the mean normal vector. The angle between the FJ surface plane

and the anatomical sagittal plane was defined as the S-angle (the lower the

S-angle, the more sagittal). The angle between the FJ surface plane and

transverse plane was also calculated and defined as the T-angle (the lower

the T-angle, the more horizontal).

RESULTS: The S-angle increased with age (p!0.0001). The S-angle for

the 20’s was smaller than the senior age groups (p!0.05; vs. 40’s and 50’s,

p!0.1; vs. 30’s). The symptomatic group showed a trend of smaller S-an-

gle (49.6 �6 8.9 �) than that in the non-symptomatic group (51.3 �6 9.1 �)(p!0.1) in the inferior FJ. The S-angle in the symptomatic group was

smaller (p!0.05) than that in the non-symptomatic group in the 30’s and

50’s (both superior and inferior FJ surfaces). No differences were shown

in the 20’s and 40’s. The T-angle decreased with level (p!0.0001) with

the lowest value being 77.4 �6 4.5 �at L4/5. There were no differences be-

tween the symptomatic and non-symptomatic groups.

CONCLUSIONS: This study has shown that the 3D orientation of the

lumbar FJs changed with age and was associated with LBP using a novel

in vivo measurement technique. The lumbar FJ orientation has been con-

sidered to be perpendicular to the transverse plane; however the current

study showed inclination from the perpendicular plane, especially in the

lower levels. This result may indicate the lumbar FJ transmits the load

in the vertical direction in addition to the anterior-posterior and rotational

directions. Our results indicated more-sagittaly oriented FJs in the symp-

tomatic group. While previous studies reported that the sagittaly oriented

FJ were associated with FJ degenerative changes, the FJ orientation was

less sagittal in the senior age group in the current study. This result may

be explained by adaptation of the FJ to the increased load transmission as-

sociated with disc degeneration in the aged group. Future study will inves-

tigate the relationship between disc and facet degeneration and changes in

FJ orientation.

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.292

P50. Interspinous Process Distraction in Lateral Decubitus vs. Prone

Position

Vijay Agarwal, MD1, Michael Wildstein1, Albi Qeli1,

Todd Alamin, MD2; 1Stanford University, Stanford, CA, USA; 2Stanford,

CA, USA

BACKGROUND CONTEXT: Interspinous process distraction (IPD) is

an emerging technique for the treatment of lumbar spinal stenosis.

Published descriptions of the technique involve treatment of patients

in the cumbersome lateral decubitus knee-chest position [1, 2]. How-

ever, many surgeons have begun to perform the procedures in various

prone positions. The patient’s positioning on the operating room table

is likely to be a major influence on the difficulty of interspinous dis-

traction, and thus implant sizing, and the potential for spinous process

fracture.

PURPOSE: To determine the comparative differences in interspinous dis-

tance in the lateral decubitus knee-chest position to that in variants on

prone positioning.

STUDY DESIGN/ SETTING: Experimental radiographic study in nor-

mal healthy male subjects.

PATIENT SAMPLE: Twenty male subjects were included in the study.

Mean age was 43.6 years (range: 24–63 years).

OUTCOME MEASURES: Interspinous process distance and interverte-

bral angulation, as measured on a PACS digital imaging system (GE PACS,

GE Integrated Imaging Solutions, Mount Prospect, IL).

METHODS: Four lateral X-rays were taken of the lower lumbar spine.

The four experimental positions were 1) ‘‘modified’’ left lateral decubitus

with knees and hips in flexion, 2) Andrews frame, 3) prone on a Wilson

frame and 4) prone on the Jackson frame. The interspinous distance was

measured from the midpoint (anterior/posterior) of the inferior surface

of the cephalad spinous process to the midpoint (anterior/posterior) on

the superior surface of the caudad spinous process. Angulation was mea-

sured across the disc from L1-S1. L4 vertebral body height was measured

for each specimen to correct for magnification.

RESULTS: At L4-5 (the most commonly implanted level), the mean spi-

nous process distance in the lateral decubitus position was 19.6+/-5.1mm.

The spinous process distances measured at L4-L5 using the Wilson frame

(15.6+/-4.6mm) and the Andrews table (23.5+/-8.3mm) were not statisti-

cally different (alpha!0.05) from that measured in the lateral decubitus

position. However, prone positioning on the Jackson table resulted in sta-

tistically significantly less distraction than all other positions (10.1+/-

4.8mm). At L4-5, the Andrews table gave a mean disc angulation of

1.50 degrees, which was statistically significantly different than �0.13 de-

grees calculated in the left lateral decubitus position. The Wilson frame

and Jackson table gave larger values of 4.58 degrees (statistically signifi-

cantly different from the left lateral decubitus position) and 7.11 degrees

respectively.

CONCLUSIONS: No significant difference was noted in the distance be-

tween the L3-L5 spinous processes on the Wilson frame, the Andrews ta-

ble, or in the modified lateral decubitus position. A trend was noted

towards increasing interspinous distance on the Andrews table, and less

on the Wilson frame. Positioning on the Jackson prone top was noted to

significantly decrease the distance between the spinous processes. For disc

angulation, the Andrews table gave statistically significant values closest to

the left lateral decubitus position. Extrapolation from this data, obtained in

healthy males younger than the typical age of patients treated with inter-

spinous distraction devices, should clearly be done with caution. However,

it seems reasonable to suggest that performing these procedures in a prone

position using the Andrews table is unlikely to result in the placement of

significantly undersized implants.

126S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.293

P51. Diagnostic Value of the Straight Leg Raise and Braggards in

Identifying Patients with Radiculopathy

Sarah A. Kelley-Spearing, BA1, Donald S. Corenman, MD, DC2, Eric

L. Strauch, PA-C2; 1Steadman Hawkins Research Foundation, Vail, CO,

USA; 2Steadman Hawkins Clinic, Vail, CO, USA

BACKGROUND CONTEXT: A positive supine straight leg raise

test(SLR) may indicate radiculopathy if leg pain is observed. A Braggards

test is then performed to differentiate nerve pain from hamstring tight-

ness. The predictive ability of SLR with Braggards varies when assess-

ing patients with dynamic radiculopathy(DR;radiculopathy worsened

with extension and relieved with flexion, i.e. foraminal stenosis, lateral

recess stenosis, central stenosis) versus non-dynamic radiculopathy

(NDR).

PURPOSE: The purpose of this study was to determine the accuracy of

diagnosing radiculopathy with Braggards. Our hypothesis was that Brag-

gards has a higher sensitivity for NDR than DR, but is a non-specific

test.

STUDY DESIGN/ SETTING: This was a case series of 98 consecutive

patients. Inclusion criteria: patients were .$18 yrs with a positive SLR de-

termined by one examiner and went on to surgery by one surgeon where

a surgical diagnosis was obtained.

PATIENT SAMPLE: 98 patients: 36 females,62 males; average age 52.8

(range:18.5-86.9); 8 work comp(WC). Patients had a primary diagnosis of

NDR, DR, or degenerative disc disease(DDD).

OUTCOME MEASURES: Degrees of SLR and Braggards were com-

pared to patients’ surgical diagnosis.

METHODS: Data was prospectively collected and retrospectively

reviewed. Degrees of SLR were compared to diagnosis using one-way AN-

OVA and the independent samples t-test was used when comparing 2 cat-

egories to a continuous variable. Comparison of Braggards and diagnosis

was done using chi square. Accuracy, sensitivity, specificity, and predictive

values were calculated using standard formulas.

RESULTS: Braggards test was significantly associated with diagnosis

(p5.01). 37 out of 44 NDRs (84%) had a positive Braggards, 21 of 38 DRs

(55%) had a positive Braggards and 9 of 16 DDDs (56%) had a positive Brag-

gards. Degrees of the SLR was also significantly associated with diagnosis

(51.02� for NDR vs. 59.06� for DDD vs. 65.92� for DR; p!.001). There was

a significant difference in degrees between NDRs and DRs(14.9�, p!.001).

There was a significant difference in age with diagnosis(p!.001;NDRs were

younger) and Braggards was associated with age (p5.041; patients with a pos-

itive Braggards were younger). WC was also significantly associated with diag-

nosis(p5.008, most WC were DDD). The accuracy of Braggards in predicting

a diagnosis of NDR (as compared to DDD) was .73(95% Confidence Interval

.64-.82), sensitivity was .84(95%CI .78-.90), specificity was .44(95%CI .26-

.61), positive predictive value(PPV) was .80(95%CI .74-.86), and negative pre-

dictive value(NPV) was .50(95%CI .29-.69). The accuracy of Braggards in pre-

dicting a diagnosis of DR (as compared to DDD) was .52(95%CI .41-.64),

sensitivity was .55(95%CI .48-.64), specificity was .44(95%CI .25-.64), PPV

was .70(95%CI .60-.81), and NPV was .29(95%CI .17-.42).

CONCLUSIONS: Degrees of SLR and Braggards are significantly asso-

ciated with diagnosis. DRs tend to have the least limitation in SLR and

have on average 14.9 degrees difference in SLR from NDRs, which tend

to have the most limitation in SLR. Braggards is a sensitive test for

NDR but not specific, with a high positive predictive value. Braggards is

not a sensitive or specific test for DR, with a high positive predictive value.

More research is needed to define an accurate diagnostic algorithm for spi-

nal diagnosis.

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.295

P52. Semi Rigid Fixation Biomechanical Feasibility in a Single-Level

Anterolateral Corpectomy Reconstruction Model

Seung-Myung Moon, MD, PhD1, Aditya Ingalhalikar, MS2,

Jason Highsmith, MD3, Alexander Vaccaro, MD, PhD, FACS4;1Neurosurgery, Hangang Sacred Heart Hospital, Hallym University, Seoul,

South Korea; 2Globus Medical, Inc., Audobon, PA, USA; 3Charleston, SC,

USA; 4Thomas Jefferson University, Philadelphia, PA, USA

BACKGROUND CONTEXT: FE (Finite Element) and animal studies on

PEEK cages with rigid posterior instrumentation have highlighted stability,