179SProceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

CONCLUSIONS: The hybrid construct had superior clinical outcome to

that of double TDAs. The clinical outcome of the hybrid group was similar

to that of single-level TDA in the literature. Two-level disc arthroplasty in

previous publications have been shown to be equivalent or inferior to the

clinical outcome of one-level TDA. This study suggests that 2-level TDA

confers no advantages when compared to hybrid constructs.

FDA DEVICE/DRUG STATUS: Maverick Medtronic USA: Not

approved for this indication.

doi:10.1016/j.spinee.2008.06.409

P162. Does Vertebral Level of Pedicle Subtraction Osteotomy

Correlate with Degree of Spinopelvic Parameter Correction?

Frank Schwab, MD1, Virginie Lafage, PhD1, Ashish Patel1, Robert Hart,

MD2, Douglas Burton, MD3, Oheneba Boachie-Adjei, MD4,

Alexis Shelokov, MD5, Richard Hostin, MD5, Christopher Shaffrey, MD6,

Munish Gupta, MD7, Shay Bess, MD8, Behrooz Akbarnia, MD8; 1NYU

Hospital for Joint Diseases, New York, NY, USA; 2Portland, OR, USA;3Kansas City, KS, USA; 4New York, NY, USA; 5Baylor Scoliosis Center,

Plano, TX, USA; 6Charlottesville, VA, USA; 7University of California,

Davis, Sacramento, CA, USA; 8San Diego Center for Spinal Disorders,

La Jolla, CA, USA

BACKGROUND CONTEXT: Pedicle subtraction osteotomy (PSO) is

a spinal realignment technique which may be used to correct sagittal spinal

imbalance (SI). Theoretically, a more caudal lumbar PSO would result in

greater correction of global sagittal balance (SVA) compared with a more

proximal PSO. The effect of PSO level on immediate post-operative spino-

pelvic parameters has not been well described.

PURPOSE: The purpose of this study is to analyze the relationship be-

tween the level/degree of PSO and changes in both global sagittal balance

and spino-pelvic parameters.

STUDY DESIGN/ SETTING: Multi-center retrospective study.

PATIENT SAMPLE: 70 patients (54 female, 16 male) that underwent

lumbar PSO surgery for sagittal imbalance (SI).

OUTCOME MEASURES: Pre and post-operative sagittal X-rays

measurements.

METHODS: Pre- and post-op free standing sagittal x-rays were obtained

and analyzed by regional curves (lumbar, thoracic and thoraco-lumbar),

pelvic parameters (pelvic incidence, pelvic tilt [PT] and sacral slope)

and global balance (SVA, T1 spino-pelvic inclination [T1-SPI]). Correla-

tions between PSO parameters (level and degree [change in angle between

the 2 adjacent vertebrae]) and spino-pelvic measurements were analyzed.

RESULTS: PSO distribution by level and degree of correction was as fol-

lows: L1 (n56; 24 �), L2 (n515; 24 �), L3 (n529; 25 �) and L4 (n520;

22 �). There was no significant difference in the focal correction achieved

by PSO by level. All patients demonstrated differences from pre-op to

post-op parameters included: increased lumbar lordosis (20 � to 29 �,p!0.001), increased thoracic kyphosis (30 � to 38 �, p!0.001), decreased

SVA and T1-SPI (122mm to 34mm, p!0.001 and �4 � to �8 �,p!0.001, respectively) and decreased PT (33 � to 23 �, p!0.001). More

caudal PSO was correlated with greater PT reduction (r5-0.410,

p!0.05). No correlation was found between SVA correction and PSO lo-

cation. PSO degree was correlated with change in thoracic kyphosis

(r5-0.474, p!0.001), lumbar lordosis (r50.667, p!0.001), sacral slope

(r50.426, p!0.001) and pelvic tilt (r5-0.358, p!0.005).

CONCLUSIONS: Degree of PSO resection correlates more with spino-

pelvic parameters (lumbar lordosis, thoracic kyphosis, pelvic tilt, sacral

slope) than PSO level. More importantly: PSO level impacts post-operative

pelvic tilt correction but not SVA. When selecting PSO level, desired PT

correction is an important consideration.

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.410

P163. TLIF as an Alternative to Formal Anterior Interbody Fusion

at the Caudal End of Long Spinal Deformity Constructs: Does it

Work?

Patrick O’Leary, MD, Lawrence Lenke, MD, Christopher Good, MD,

Mark Pichelmann, MD, Kathryn Keeler, MD, Keith Bridwell, MD,

Brenda Sides; Washington University in St. Louis, St. Louis, MO, USA

BACKGROUND CONTEXT: Structural interbody support at the distal

end of a fusion construct for adult spinal deformity has routinely been ac-

complished via anterior lumbar interbody fusion (ALIF). The viability of

TLIF to achieve similar measures was investigated.

PURPOSE: Transforaminal lumbar interbody fusion (TLIF) has been used

extensively in the treatment of degenerative spinal disorders. TLIF has not

been reported in spinal deformity treatment. We hypothesized that at the

caudal end of deformity constructs, TLIF would result in similar fusion

rates, maintenance of local lordosis, similar outcomes, and shorter hospital

stay compared to formal anterior lumbar interbody fusion (ALIF).

STUDY DESIGN/ SETTING: Retrospective matched cohort analysis.

PATIENT SAMPLE: 17 adult deformity patients (TLIF) and a matched

group of 17 patients (ALIF) with minimum 2 year follow-up.

OUTCOME MEASURES: Radiographic/clinical criteria; Scoliosis Re-

search Society (SRS-30) and Oswestry scores.

METHODS: The senior author has utilized TLIF (TLIF group) in order to

obtain structural interbody fusion at the caudal aspect of long deformity

constructs (thoracic to L5 or S1). 17 patients had minimum 2-year clini-

cal/radiographic follow-up. A matched cohort of 17 patients who under-

went staged formal ALIF (ALIF group) following posterior spinal

instrumentation and fusion for deformity. Diagnoses included double ma-

jor scoliosis (TLIF n57, ALIF n58), lumbar scoliosis (n56; n55), con-

genital scoliosis (n51; n51), and distal transition syndrome following

prior fusion for idiopathic scoliosis (n53; n53). Radiographic analysis in-

cluded local lordosis at interbody levels, overall lumbar lordosis, and A/P

fusion grade, as graded by three independent observers.

RESULTS: 17 patients had a total of 24 TLIFs (11-L5/S1, 12-L4/5, 1-L3/4);

17 patients in the matched cohort had a total of 40 ALIFs (15-L5/S1, 15-L4/

5, 10-L3/4); all utilized structural cages. Rh-BMP2 (12mg/level) was used in

180S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

14/17 TLIFs and 15/17 ALIFs. Age, preop AP lumbar curve, and lumbar lor-

dosis were similar between groups (Table). Average operative time for TLIF

group was 499 minutes vs 628 for the combined posterior and anterior sur-

geries in the ALIF group (p5.004). Length of stay was significantly shorter

in the TLIF group (7.6 days) vs ALIF (13.5 days) (p!0.0001). Interbody fu-

sion rates were similar between groups with no cases of cage, screw, or rod

implant failure at the interbody levels in either group.

CONCLUSIONS: TLIF resulted in maintenance of local intervertebral

lordosis, similar fusion rates, and similar improvement in Oswestry scores

compared to a matched cohort of ALIF patients. Operative times and

length of stay were significantly reduced in the TLIF group. There were

no cases of implant failure at the interbody levels in either group. TLIF

at the caudal aspect of a long construct is a viable option for anterior col-

umn fixation in adult deformity patients.

FDA DEVICE/DRUG STATUS: rh-BMP2: Not approved for this

indication.

doi:10.1016/j.spinee.2008.06.411

P164. Calmodulin Antagonists Decrease the Rate of Progression and

Severity of Scoliosis

Ibrahim Akel1, Ahmet Alanay, MD2, Gokhan Demirkiran1, Emre Acaroglu,

MD1; 1Ankara, Turkey; 2Hacettepe University Faculty of Medicine,

Ankara, Turkey

BACKGROUND CONTEXT: Calmodulin probably has a regulatory role

in muscle contraction and its’ antagonism may decrease the magnitude as

well as the progression of scoliosis. A separate study has shown especially

tamoxifene (TMX), a known antagonist to be effective in altering the nat-

ural history in an avian model, it remains to be seen whether the same

effect is conceivable in mammals.

PURPOSE: This study aimed to analyze whether the natural course of id-

iopathic like scoliosis in pinealectomized chicken may be altered by the

administration of calmodulin antagonists.

STUDY DESIGN/ SETTING: Experimental study.

OUTCOME MEASURES: PA scoliosis X-rays were taken at 20th and

40th weeks and evaluated for presence and magnitude of spinal curves.

METHODS: 60 female 3-week-old C57BL/6 mice underwent amputa-

tions of forelimbs and tails. Available 57 were grouped as Gr C, no med-

ications; Gr TMX, 10mg-TMX/lt drinking water and Gr combined, 10mg

TMX+10mg trifluoperazine (TFP)/lt drinking water. Pearson Chi-square

test to compare curve incidences between and within the groups, ANOVA

and Kruskall Wallis tests were used to compare the Cobb angles. Curve in-

cidence changes within groups by time were compared by paired t-tests.

RESULTS: 4 mice were lost in the TMX group. Overall scoliosis rate was

significantly lower in this group (33%) compared to control (90%) and

combined drug groups (68%) (p50.001) at 40th week. Likewise, upper

thoracic scoliosis rate (27%) compared to control (74%) and combined

drug groups (47%) (p5 0,01); lower thoracic scoliosis rate (7%) group

compared to control (63%) and combined drug groups (26%) (p5

0,001) were lower in TMX group. Combined drug group had lower tho-

racic and lumbar Cobb angles (17,5063,45) compared to control group

(29,4065,98) (p5 0,031). Furthermore, double curve incidence at 40th

week was lower in TMX group (12%) compared to control (74%) and

combined drug groups (47%) (p50,001), triple curve incidence was also

lower in combined (0%) and TMX drug groups (6%) compared to control

group (15%) but was not significant (p50,167).

CONCLUSIONS: Tamoxifen is shown to effectively decrease the incidence

and magnitude of the scoliotic curves in C57BL/6 mice scoliosis model.

FDA DEVICE/DRUG STATUS: tamoxifene: Investigational/Not

approved.

doi:10.1016/j.spinee.2008.06.412

P165. Characterizing Radiographic Changes in 102 Consecutive

Cases of Degenerative Spondylolisthesis

Thomas Lawhorne, III, MD, Ioannis Pappou, MD, Frank Cammisa, Jr.,

MD, Federico P. Girardi, MD; Hospital for Special Surgery, New York, NY,

USA

BACKGROUND CONTEXT: Degenerative spondylosthises (D-S) is

a result of spondylotic changes of the apophyseal joints and disc narrow-

ing and is commonly associated with spinal stenosis and neurogenic clau-

dication. However, there exists a void in the literature characterizing the

spectrum of degenerative changes found in D-S. Degenerative spondylo-

listhesis is most often classified utilizing the Meyerding classification

which characterizes the severity of the slip, but does not take into

account any of its spondylotic component. In fact, the classification itself

was originally designed to describe slippage in the setting of pediatric

spondylolytic spine, in which the etiology of slippage is completely

different.

PURPOSE: In an effort to better describe the presentation of degenera-

tive spondylolisthesis, we examined the radiographs of patients that

underwent surgery for degenerative spondylolisthesis. We cataloged

radiographic changes that are associated with the slippage and

degeneration.

STUDY DESIGN/ SETTING: Retrospective radiographic study from

cases of the senior authors’ practices.

PATIENT SAMPLE: We conducted a retrospective chart and image re-

view of the last 102 consecutive cases operated on by the two senior au-

thors prior to 9/1/2005.

OUTCOME MEASURES: Each patient’s pre-operative demographic in-

formation, plain films, and MRIs were reviewed.

METHODS: From plain AP and lateral films we recorded percent slip-

page, Meyerding classification, slip level, disk heights, and any scoliotic

curves in the lumbar spine. Flexion and extension radiographs were re-

viewed to evaluate reduction and record ROM at each lumbar level.

RESULTS: Of the 102 patients, 61% were female and the average

patient age was 68 years. 85.2% of slips occurred at the L4-5 level.

8.3% and 6.5% of slip occurred at L3/4 and L5/S1 levels, respectively.

6 of the 102 patients had radiographic slips at two adjacent levels. Two

levels slips accounted for 5.6% of patients. All double slips included

L4/5 level, and were paired evenly (50%/50%) with L3/4 and L5/S1.

Average range of motion at the level of slip was 6.7 degrees contribut-

ing 21.5% of total lumbar motion. Slip percentage varied greatly in our

sample: the average was 17.8% but varied with 12.8% in one standard

deviation. Anterior translation of the superior over the inferior lumbar

body average 6.2mm in neutral, worsened to 7.2mm in flexion, and cor-

rected to 5.3mm in extension. Disk height at the slip level and above

the slip averaged 8.6mm and 10.8mm, respectively. 21.6% of slips re-

duced to within 3mm translation in extension. Central stenosis and facet

changes were significantly worse at the level of the slip. All indicators

improved cephalad to the level of the slip. 54.6% of all D-S spines had

measurable coronal curves. However, these curves average only 12.5

degrees.

CONCLUSIONS: The literature to date has lacked a comprehensive

evaluation of degenerative spondylolisthesis in the context of its demo-

graphics and degenerative characteristics. It is important to identify

this disease as degenerative process unlike spondylolysis. By surveying

a variety of radiographic indicatiors of instability and spondylosis, we

have prioritized characteristics in evaluating degenerative spondylo-

listhesis. Using this data, we identified patterns of presentation. This

will have implications for future projects including adaptation a classi-

fication system that is specific for the degenerative form of

spondylolisthesis.

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

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.413