153SProceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S

traumatic spinal cord injury (tSCI) in 12 major cities across Canada.

RHSCIR collects both the clinical diagnoses for neurological impairment

and spinal column injuries, in addition to the administrative ICD-10 diag-

nosis codes assigned by health record coders. This enables one to evaluate

the validity of the administrative codes.

PURPOSE: To examine the sensitivity, specificity, and positive predictive

value (PPV) of ICD-10 codes compared to the clinical diagnoses for neu-

rological impairment and spinal column injuries recorded in the RHSCIR.

STUDY DESIGN/SETTING: Retrospective review of clinical diagnoses

and administrative codes.

OUTCOME MEASURES: Neurological impairment is classified in

RHSCIR using the International Standards for Neurological Classification

of Spinal Cord Injury and spinal column diagnoses are recorded using the

RHSCIR spinal column injury diagnosis form. Administrative ICD-10 di-

agnosis codes are obtained from the hospital database for patients enrolled

in RHSCIR.

METHODS: 555 patient-records from RHSCIR at the Vancouver site

were included. Canadian ICD-10 codes used to diagnose tSCI and spinal

column injuries were mapped to the International Standards for Neurolog-

ical Classification of Spinal Cord Injury and the most specific RHSCIR

spinal column injury diagnostic codes, respectively. Twenty-five ICD-10

neurological impairment codes and 28 ICD-10 spinal column injury codes

were evaluated for their sensitivity (true positives), specificity (true nega-

tives) and PPV (proportion of ICD-10 codes correctly assigned). The pro-

portion of patients with a tSCI enrolled in the RHSCIR that were not

considered to have a tSCI using the ICD-10 codes was assessed.

RESULTS: 506 patients in the RHSCIRwere used to assess the ICD-10 co-

des pertaining to neurological impairment and 278 patients were included in

the analysis of the ICD-10 codes for spinal column injuries. 40 patients

(7.9%) were diagnosed in RHSCIR as having a tSCI but were missed using

the ICD-10 codes. Overall, specificity was fair for both the neurological

impairment codes and spinal column codes (range: 0.52�1) while sensitiv-

ity was highly variable. The PPVs for the ICD-10 codes pertaining to ASIA

Impairment Scale A injuries ranged from 0.47 to 0.77.

CONCLUSIONS: Administrative coding cannot be reliably used to clas-

sify types of tSCI or spinal column injuries. Research relying on the anal-

ysis of large administrative data sets may lack precision and relying on

prospective clinical registries, such as the RHSCIR, are a more valuable

resource of detailed diagnostic data for research purposes.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.367

P66. In vitro Biomechanical Comparison of the Native Intervertebral

Disc and a Compliant Artificial Lumbar Disc Replacement

(Cadisc-L)

Scott Johnson1, Jason Naylor2, Donal McNally, PhD; 1Ranier

Technology Ltd, Cambridge, UK; 2The University of Nottingham,

Nottingham, UK

BACKGROUND CONTEXT: Lumbar Total Disc Replacement (TDR)

seeks to restore ‘‘physiological’’ motion and biomechanical properties of

the natural disc with the potential to reduce the risk of adjacent segment

disease associated with spinal arthrodesis. A variety of low friction TDR

designs are available; implants that restore the elastomeric properties of

the disc are of significant interest for their potential to restore near normal

biomechanics.

PURPOSE: This study tests the hypothesis that implantation of the

Cadisc�-L elastomeric lumbar TDR does not significantly change the

overall biomechanical behavior of cadaveric human motion segments.

Specifically, the effects of implantation on the following parameters are re-

ported:Location of the Centre of Rotation (CoR)Compressive stiffness-

Bending moment vs. bending angle characteristics, particularly the range

of motion at 15 Nm and the bending stiffness at 6�.

All referenced figures and tables will be available at the Annual Mee

STUDY DESIGN/SETTING: An in-vitro biomechanical study using ca-

daveric motion segments.

PATIENT SAMPLE: Ten fresh frozen cadaveric motion segments.

OUTCOME MEASURES: Axial compressive stiffness, flexural stiffness

andCoR characteristics for themotion segment before and after implantation.

METHODS: Ten fresh frozen cadaveric motion segments were dissected

to remove all non-osteoligamentous tissue. This number was determined

using a power analysis (p5.05, a50.8) to detect differences greater than

the sample standard deviation. Care was taken to preserve specimen hydra-

tion. The L4-5 motion segments were mounted in loading cups using the

low melting point alloy.Testing was performed in an environmental cham-

ber at 37 �C with 95–100% humidity. Specimens were pre-conditioned

with a 500 N load for 30 minutes to restore near normal levels of disc hy-

dration. The location of the static CoR was determined by adjusting the

anterior/posterior position of a single loading roller until no flexion/exten-

sion was produced on application of a small test load. Compressive stiff-

ness of the specimen was determined on the 5th of a series of 5 loading

cycles to 1kN; load was applied at a rate of 250 N/s. The bending stiffness

of the specimen was determined by a physiologically relevant combination

of bending moment, compressive load and forward shear. The position of

the roller was offset to 12.5 mm anterior to the static CoR producing

a bend. Bending angle, measured using an electronic inclinometer, was

used to calculate the bending moment from the applied load and roller off-

set geometry. Again the data was captured on the 5th of 5 cycles. Follow-

ing testing of the intact motion segment, the intervertebral disc was

removed and a medium-sized Cadisc�-L implant inserted. The location

of the new CoR was determined and the mechanical testing protocol re-

peated. Data from the intact and implanted conditions were then compared

using paired students ‘t’ tests.

RESULTS: Compressive stiffness and bending stiffness were reduced by

50% and 20.5% respectively following implantation of the Cadisc�-L.

The instantaneous axis of rotation locus maintained its characteristics with

a centrode displaced 4.1 mm at 3� flexion.

CONCLUSIONS: The results of this study support the hypothesis that

implantation of the elastomeric TDR, Cadisc�-L, produces very similar

in-vitro biomechanical behaviour to that of the native intervertebral disc.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.368

P67. Postoperative Outcomes in Adult Scoliosis: A Prospective

Multicenter Database with Three-Year Follow-Up

Michael Weber, MD, PhD1, Steve Takemoto, PhD1, Jian Shen, MD, PhD2,

Amir Abdul-Jabbar2, Linda Racine3, Sigurd Berven, MD4; 1University of

California San Francisco, San Francisco, CA, USA; 2San Francisco, CA,

USA; 3Scoliosis Association of San Francisco, El Granada, CA, USA;4University of California San Francisco, Department of Orthopaedic

Surgery, San Francisco, CA, USA

BACKGROUND CONTEXT: Spinal surgery provides significantly

greater improvement in both pain and disability in adults with scoliosis,

however the postoperative timing of improvement has not been studied.

Thus, we assessed the postoperative quality of life outcomes using survey

data at defined time points. Our results will provide a guideline for coun-

seling adults with scoliosis on expected outcomes after spinal surgery.

PURPOSE: Examine in adult scoliosis the postoperative timing of im-

provement in quality of life outcomes.

STUDY DESIGN/SETTING: This was a retrospective review.

PATIENT SAMPLE: Data extracted from a prospective, multicenter da-

tabase for adult spinal deformity.

OUTCOME MEASURES: At first encounter and follow-up (3 and 6

months, one, two and three year) patients completed the Oswestry Disability

Index (ODI) and SF-12 physical and mental component summary scales

(PCS-12 and MCS-12, respectively).

ting and will be included with the post-meeting online content.

154S Proceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S

METHODS: We controlled for age, primary vs. revision, stage, complex-

ity (osteomotomy and levels), and complications (intra and post-operative).

RESULTS: A total of 2552 patients had 3 years of outcome data, and were

included in the analysis. At baseline, elderly patients (O60 years) had more

disability (ODI, p!.001), and poorer health status (SF-12 PCS, p!.001).

People requiring a revision (ODI, p!.001; MCS, p!.05; PCS!0.001)

and cases requiring an osteotomy were consistently worse at baseline

(ODI, p!.001; MCS, p!.05; PCS!0.001). At 3 months, younger patients

(ODI, p!.001; PCS!0.01), no osteotomy (ODI, p!.001; PCS, p!.01), sin-

gle stage (ODI, p!.001; PCS, p!.001) and primary procedures (ODI,

p!.01) did better. At 6 months, younger patients (ODI, p!.001; PCS,

p!.001), no osteotomy (ODI, p!.01), single stage (ODI, p!.01; PCS,

p!.05) and primary procedures (ODI, p!.001; MCS, p!.001; PCS,

p!.001) continue to do better. At 1 year, younger patients (ODI, p!.01;

PCS, p!.001), no osteotomy (ODI, p!.001; PCS, p!.01), and primary

procedures (ODI, p!.001; PCS, p!.001) still show improvement. Interest-

ing, a single procedure no longer shows a benefit and the intra-operative

complication group (ODI, p!.01) continue to do worse. By 3 years, youn-

ger patients (ODI, p!.001; PCS!0.001) and no osteotomy (ODI, p!.001;

MCS, p!.05; PCS, p!.05) have the best QOL outcomes.

CONCLUSIONS: Surgical treatment has the potential to significantly im-

prove the quality of life of the patients with adult scoliosis. Older patients

and less complex surgeries requiring no osteotomies have a better quality

of life consistently thought out the postoperative period up to three years.

In the first 6 months after surgery, primary single stage procedures do bet-

ter. An understanding of the outcomes after surgery will improve both the

counseling of surgical candidates and patient care pathways.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.369

P68. Traditional Open Versus Minimally Invasive Decompression

and Fusion of the Lumbar Spine: A Retrospective Analysis

Melissa McKeon1, Neil Manson, MD, FRCSC2, Edward Abraham, MD2;1Canada East Spine Centre, Saint John, NB, Canada; 2Saint John Regional

Hospital, Saint John, NB, Canada

BACKGROUND CONTEXT: Currently, the literature provides abundant

evaluation of both traditional open (OPEN) and minimally invasive surgi-

cal (MIS) techniques for lumbar decompression and fusion, however there

are few direct comparisons. It is imperative that these newer technologies

be carefully analyzed against our accepted traditional techniques in an ef-

fort to confirm optimal patient treatment.

PURPOSE: To provide direct comparison of OPEN versus MIS decom-

pression and fusion for lumbar degenerative spine pathology and toidentify

advantages and pitfalls of one technique versus another.

STUDY DESIGN/SETTING: A retrospective review identified patients

who received a single level lumbar decompression and fusion procedure

for degenerative spine pathology between 2006 and 2009.

PATIENT SAMPLE: 187 patients receiving a single level lumbar decom-

pression and fusion procedure were identified. Of the 187, 141 (OPEN590,

MIS551) met the inclusion criteria and were included in the analysis. All

surgeries were performed at a single institution with pre and post-operative

protocols remaining the same for both groups.

OUTCOME MEASURES: Intra-operative data: Patient demographics

(height, weight, BMI, smoking status, etc.) and patient completed question-

naires (ODI, VAS Back and Leg). Intra-operative data: blood loss, surgical

time, and complications. Post-operative data: hospital stay, complications,

revision rates, and patient completed questionnaires.

METHODS: A surgical database identified patients. Chart review provided

demographic and operative data. OPEN patients received midline incision,

subperiosteal muscle dissection, wide decompression, TLIF or PLIF, poste-

rior instrumentation, and posterolateral bone graft. MIS patients received

paramedian incision, muscle splitting with tubular retractor, unilateral or

All referenced figures and tables will be available at the Annual Mee

bilateral decompression, TLIF, and posterior instrumentation. Minimum

1-year follow up was completed. Data were analyzed using an ANOVA

(p!.05) to detect significant differences between MIS and OPEN groups.

RESULTS: Both surgical groups demonstrated statistically similar pre-

operative demographics (age, gender, BMI, ODI, VAS Leg and Back).

The OPEN procedure demonstrated statistically greater blood loss before

(519.6 vs. 259.4 ml) and after (377.5 vs. 232.2 ml) Cell Saver blood return

with significantly shorter operative time (124.1 vs. 194.4 min). Otherwise,

all other measures were similar. Intra-operative and post-operative compli-

cations, hospital stay, and revision rates were equal. At one year follow-up,

both groups displayed a similar drop in ODI (OPEN: 50.7 to 29.3%, MIS:

55.7 to 39.6%), VAS Leg (OPEN: 7.4 to 4.3, MIS: 7.3 to 4.1), and VAS

Back (OPEN: 7.8 to 3.6, MIS: 7.5 to 4.5).

CONCLUSIONS: Specific surgical approach techniques may offer certain

advantages to optimize outcomes. Ultimately, appropriate technique at the

level of the spine to provide decompression and stabilization should ulti-

mately dictate surgical success. Future work should focus on pre-operative

decision making, operative challenges, and objective biomechanical mea-

sures to assure similarity between techniques.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.370

P69. Outcomes and Complications of Minimally Invasive Correction

for Adult Degenerative Scoliosis

Atiq Durrani, MD1, Nael Shanti, MD, Rehan Puri, MD1,

Rachel Mistur, MS1; 1Center for Advanced Spine Technologies, Cincinnati,

OH, USA

BACKGROUND CONTEXT: Minimally invasive surgery has been in-

creasingly used for the correction of spinal deformity.

PURPOSE: The object for this study is to analyze complication rates and

outcomes in 45 patients with degenerative scoliosis treated with minimal

invasive correction and fusion.

STUDY DESIGN/SETTING: We performed a retrospective chart review

of 45 patients who received minimally invasive surgical correction for

adult degenerative scoliosis at 3þ levels.

PATIENT SAMPLE: The present study included 12 males and 37 females

with an average age of 53.4 years. Average levels of fusion were T10-S1 in

80% cases and L2-S1 in the residual cases.

OUTCOME MEASURES: VAS pain scores as well as Oswestry Disabil-

ity Index (ODI) were collected pre- and post-op. Pre-op and post-op Cobb

angles as well as sagittal profile with the C7 plumb line were also mea-

sured. Perioperative complications were also analyzed.

METHODS: All patients had two-stage reconstruction surgeries separated

by a 4–6 weeks. Stage 1 involved a lateral lumbar interbody fusion and

stage 2 required percutaneous spinal fusion and AxiaLIF at L5-S1. The

surgical and outcome data was collected and analyzed for the purposes

of this study.

RESULTS: Estimated blood loss for the stage I was 52 (615) ml and 213

(6112) ml for stage II. The mean operative time for stage I was 160

(6100) min and stage II was 269 (6130) min. The mean length of hospital

stay for stage I was 2.0 (61.0) days and stage II was 3.2 (61.4) days. The

preoperative Cobb angle was 36�, which corrected to 9� post-op. The C7

plumb line sagittal profile averaged 6.2 cm pre-op and corrected to

1.7 cm after surgery. The mean pre-op VAS58.20 and post-op53.01.

The mean ODI score at pre-op was 50.3% and 8.5% at post-op. There

was a significant decrease in VAS and ODI post-op (p!.001). Superficial

wound complications were identified in 6 patients (13%). There were no

documented vascular or rectal bowel complications.

CONCLUSIONS: Our analysis of 45 patients receiving minimally inva-

sive correction for degenerative scoliosis show very low complication rates

overall. Patients also demonstrate excellent correction of coronal and sag-

ittal plane deformity post-op. VAS and ODI scores also show significant

ting and will be included with the post-meeting online content.