adolescent idiopathic scoliosis patients are at increased risk for pulmonary hypertension which...

153SProceedings of the NASS 29th Annual Meeting / The Spine Journal 14 (2014) 1S–183S

perioperative morbidity. The use of minimally invasive surgery (MIS) for

correction of ADS has been theorized to lower the perioperative morbidity

when compared to traditional open surgical approaches. However, there is

concern that patients treated with MIS techniques will not achieve the

same level of clinical improvement as those treated with traditional open

surgery approaches. This study compared patients treated with MIS

(MIS lateral or transforaminal interbody fusion (LIF or TLIF) with percu-

taneous pedicle screw fixation), hybrid techniques (HYB) (MIS LIF or

TLIF in combination with open posterior pedicle screw fixation), and open

techniques to assess ODI at 1 and 2 years.

PURPOSE: To compare disability outcomes between open and MIS de-

formity surgery.

STUDY DESIGN/SETTING: Retrospective review of propensity

matched cohorts.

PATIENT SAMPLE: 120 patients with adult deformity treated with MIS,

hybrid or open surgeries.

OUTCOME MEASURES: Radiographic parameters and ODI.

METHODS: All cases were reviewed retrospectively. Inclusion criteria

included: ageO18yr, ASD, min 2-yr follow-up. Patients treated for adult

spinal deformity using either less invasive or open surgical approaches

were propensity matched by preop SVA, baseline ODI, and by number

of fused levels. Patients’ results were compared at 1 and 2 years postop.

RESULTS: 40 patients were propensity matched into each group for a to-

tal number of 120. Mean number of levels fused and SVAwas HYB5 5.9,

37.7mm, MIS 5 3.7, 30.7mm, OPEN 5 6.0, 47.5 mm. At baseline, ODI

was: HYB569.6, MIS549.7, Open549.6. At postop 1 year patients re-

ported significantly improved ODI (P!0.01 when compared to baseline)

(HYB537.3, MIS526.8, Open535.6) (between groups PO0.05). At 2

years the patients maintained improvement in disability (HYB537.5,

SVA 43.6, MIS 28.0, SVA 34.5, and Open 30.6, SVA 33.5).

CONCLUSIONS: Patients treated with MIS techniques can achieve sim-

ilar reductions in disability to those treated with open deformity surgery.

When matched by SVA, number of levels and baseline ODI, there was

no statistically significant difference in disability at 1 and 2 years after

surgery.

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

any applicable devices or drugs.

http://dx.doi.org/10.1016/j.spinee.2014.08.369

P116. Pedicle Screw Safety: How Much Anterior Breach is Safe? A

Cadaveric- and CT-Based Study

Vishal Sarwahi, MD1, Terry D. Amaral, MD2, Monica Payares, MD3,

Aviva Dworkin3, Dan Wang4, Adam L. Wollowick, MD2; 1New York, NY,

US; 2Bronx, NY, US; 3Montefiore Medical Center, Bronx, NY, US; 4Albert

Einstein College of Medicine, Bronx, NY, US

BACKGROUND CONTEXT: Pedicle screw misplacement rate varies

from 6%-15%. Most commonly these misplacements are anterior or ante-

rolateral and these can potentially endanger vital structures. While the lim-

its of medial breach (!3mm) are known, the safe limits for anterior/

anterolaterally breach are not yet defined.

PURPOSE: Purpose is to determine the safety limits of an anterior/ ante-

rior lateral misplaced pedicle screw in spinal deformity.

STUDY DESIGN/SETTING: Basic science/cadaveric/retrospective.

PATIENT SAMPLE: Eight cadavers were instrumented and postoperative

CT scans of 165 patients operated on for spine deformity were reviewed.

OUTCOME MEASURES: Fisher’s exact test.

METHODS: This study had two parts. In part I, 8 cadavers were instru-

mented with 6 x 30mm and 6x40mm bilaterally from T1-S1. Screws were

randomly inserted under navigation guidance into 3 positions: in, out me-

dial, out anterior laterally. CT scan was performed, followed by gross dis-

section to determine screw position. In part II, postoperative CT scans of

165 patients operated on for spine deformity were reviewed for screw mis-

placement (2800 screws). The amount of breach for anterior/anterolateral

Refer to onsite Annual Meeting presentations and postmeeting proceedings for po

reporting disclosures and FDA device/drug

was measured. Protrusions were also evaluated for proximity to vital struc-

tures. All scans were reviewed by musculoskeletal radiologist.

RESULTS: Part I: 285 screws were inserted. 93 were misplaced anterior/

anterolaterally. On gross dissection, 89 were misplaced; 67 protruded

through soft tissue and were easily visualized while 32 were covered en-

tirely by soft tissue but were palpable. These 32 screws did not endanger

any structures. All 32 screws protruded!4mm on CT scan. Part II: 117

(4.14%) screws were misplaced anterior/anterolaterally. 31 (26.5%) were

adjacent to vital structures. Fisher’s exact test showed!4mm breach has

significantly lower likelihood of impingement (p!0.001) and sensitivity

81%. Screws adjacent/impinging the aorta protruded an avg 5.7 mm (SE

0.6), while screws not involving the aorta breached an avg 3.9 mm (SE

0.2), p50.005.

CONCLUSIONS: Anterior/anterolateral breaches!4mm on CT poses no

significant risk of impingement and therefore can be considered safe.




P117. Adolescent Idiopathic Scoliosis Patients Are at Increased Risk

for Pulmonary Hypertension which Reverses After Scoliosis Surgery

Vishal Sarwahi, MD1, Rachel E. Borlack, BS2, Aviva Dworkin3,

Dan Wang4, Sarika Kalantre, MD5; 1New York, NY, US; 2Bronx, NY, US;3Montefiore Medical Center, Bronx, NY, US; 4Albert Einstein College of

Medicine, Bronx, NY, US; 5Children’s Hospital at Montefiore, Bronx,

NY, US

BACKGROUND CONTEXT: The incidence of structural cardiac disease

and pulmonary hypertension in Adolescent Idiopathic Scoliosis (AIS) pa-

tients has been infrequently studied. Pulmonary hypertension has a high

mortality rate.

PURPOSE: The purpose of this study is to determine the incidence of struc-

tural cardiac anomalies and pulmonary hypertension in AIS patients and its

relationship with curve severity. This is the first study to document evidence

of pulmonary hypertension (pulm HT) in AIS patients, the severity of which

directly correlates with the size of the curve. Pulmonary hypertension,which

can potentially be fatal, reverts to normal after corrective scoliosis surgery.

These findings provide direct evidence of immediate benefit of scoliosis sur-

gery and can change the entire scoliosis treatment paradigm.

STUDY DESIGN/SETTING: Retrospective study.

PATIENT SAMPLE: 107 AIS patients whom had screening

echocardiograms.

OUTCOME MEASURES: Spearman correlation and Logistic Regres-

sion analysis.

METHODS: Retrospective review of AIS pts with PSF from ‘09 –‘12 was

done. 2D echos where reviewed for structural heart disease, aortic root

size, and Tricuspid regurgitant jet velocity (TRV). Right ventricular sys-

tolic pressure (RVSP) was estimated using the Bernoulli’s equation

(4*(TRV)2 þ right atrial pressure). RVSPO 25mm Hg was indicates pul-

monary hypertension. 2D echo of 100 aged matched health adolescents

served as control.

RESULTS: 160 pts had spinal fusion surgery in the study period. Of these,

120 had AIS and 107 AIS pts (72F:35M) had screening 2D echos. Average

age was 14.8 6 2.2 years. Average Cobb angle was 50.9612.3�. 2 AIS pts

had ASD, 2 had VSD, and 3 had MVP, while 64 pts had mild to trivial mi-

tral regurgitation. 24 AIS pts had higher incidence of mild tricuspid regur-

gitation (p!0.001) and higher TRV/ RVSP (O25 mm Hg) (p50.04)

indicating pulmonary HT. Spearman correlation coefficient between Cobb

angle and RVSP was 0.32 in AIS (p50.04). This is a significant correlation

between increasing Cobb and worsening RVSP. Logistic Regression

showed an odds ratio of 3.29 for elevated TRV (meaning increased pulmo-

nary HT) in AIS (p 5 0.007).18 out of 24 AIS patients with elevated TRV/

RVSP had 2D echo at 2 year post-op. All had normal RVSP (mean 20.4

mm Hg), which shows reversal of pulmonary HT to normal values.

ssible referenced figures and tables. Authors are responsible for accurately

status at time of abstract submission.



154S Proceedings of the NASS 29th Annual Meeting / The Spine Journal 14 (2014) 1S–183S

CONCLUSIONS: Screening 2D echo identifies structural heart defects

and pulm HT. Scoliosis surgery prevents progression and reverses pulm

HT, avoiding potentially fatal compromise. This is the first study to docu-

ment evidence of pulmonary hypertension (pulm HT) in AIS patients, the

severity of which directly correlates with the size of the curve. Pulmonary

hypertension, which can potentially be fatal, reverts to normal after correc-

tive scoliosis surgery. These findings provide direct evidence of immediate

benefit of scoliosis surgery and can change the entire scoliosis treatment

paradigm.




P118. Pedicle Screws Allow Maintenance of Thoracic Kyphosis in

AIS, but Ability to Improve Hypokyphosis is Limited

Vishal Sarwahi, MD1, Adam L. Wollowick, MD2, Preethi M. Kulkarni,

MD3, Terry D. Amaral, MD2; 1New York, NY, US; 2Bronx, NY, US;3Montefiore Medical Centre, Bronx, NY, US

BACKGROUND CONTEXT: Pedicle screw instrumentation in AIS has

been shown to produce hypokyphosis. Contributing factors may include

rod size, material, and correction maneuvers. This study seeks to evaluate

the ability of pedicle screws to maintain normal kyphosis or restore normal

kyphosis in patients with preoperative hypokyphosis.

PURPOSE: The purpose of this study is evaluate the ability of pedicle

screw to maintain normal kyphosis.

STUDY DESIGN/SETTING: Retrospective study.

PATIENT SAMPLE: 236 AIS patients who underwent PSF.

OUTCOME MEASURES: Frequency and generalized linear model.

METHODS: 236 AIS patients who underwent PSF utilizing pedicle

screws between 2004 and 2011 were evaluated for kyphosis (T3-12),

sagittal balance and proximal junction kyphosis (O 10�). Charts as well

as preop, immediate postop, one- and two-year postop X-ray images were

reviewed.

RESULTS: 83 patients met inclusion criteria. Sixty (72%) had normal

preop kyphosis. Immediately post-op, 81% of patients had normal ky-

phosis. At one year, 83% had normal kyphosis and 72% at 2 years,

(p50.32). Rod translation, rod derotation and DVR were not found to

have a hypokyphosing. Patient and curve characteristics, length of fu-

sion, LIV and number of screws were not found to have a significant

effect on kyphosis. 85% with normal preop kyphosis maintained it at

2 years, and 15 % of these patients had hypokyphosis postop and re-

mained unchanged at 2 years. 60.9% of patients with preop hypokypho-

sis were restored to normal thoracic kyphosis and maintained at 2

years. Patients did not significantly change their sagittal balance at 2

years. The use of high strength rods did not improve maintenance or

restoration of thoracic kyphosis. No significant incidence of PJK,

p50.92.

CONCLUSIONS: Pedicle screws did not produce hypokyphosis and

allow the surgeon to maintain kyphosis in patients with normal kyphosis.

No specific curve characteristics or surgical maneuver was found to nega-

tively influence kyphosis. Further attention needs to be paid to patients

with preop hypokyphosis as only 60% were normalized.




P119. Minimally Invasive versus Open Sacroiliac Joint Fusion:

A Comparison of Outcomes in Propensity Matched Cohorts

Charles Gerald T. Ledonio, MD1, David W. Polly, Jr., MD2,

Marc Swiontkowski, MD3; 1Minneapolis, MN, US; 2University of

Refer to onsite Annual Meeting presentations and postmeeting proceedings for po

reporting disclosures and FDA device/drug

Minnesota Physicians, Minneapolis, MN, US; 3University of Minnesota

Department of Orthopaedic Surgery, Minneapolis, MN, US

BACKGROUND CONTEXT: The sacroiliac joint has been implicated as

a source of chronic low back pain in 15% to 30% of patients. When non-

surgical approaches fail, sacroiliac joint fusion may be recommended. Ad-

vances in intraoperative image guidance have assisted minimally invasive

surgical (MIS) techniques using ingrowth-coated fusion rods; however,

how these techniques perform relative to open anterior fusion of the sac-

roiliac joint using plates and screws is not known.

PURPOSE: To compare minimally invasive surgical (MIS) techniques us-

ing ingrowth-coated fusion rods against open anterior fusion of the sacroil-

iac joint using plates and screws on process measures (blood loss, surgical

time, hospital stay) and Oswestry Disability Index (ODI).

STUDY DESIGN/SETTING: Retrospective chart review at single

institution.

PATIENT SAMPLE: From 2006 to 2011, a total of 63 patients underwent

sacroiliac joint fusions (open: 36; MIS: 27). Of those, 10 in the open group

had incomplete records and were excluded.

OUTCOME MEASURES: Process measures (blood loss, surgical time,

hospital stay) and ODI.

METHODS: We performed a retrospective study of patients who

underwent sacroiliac joint fusion with minimum 1-year follow-up at

a single institution to compare process measures and ODI scores be-

tween the two techniques. All patients had sacroiliac joint dysfunction

confirmed by image-guided intraarticular anesthetic sacroiliac joint in-

jection and had failed nonoperative treatment. Patients were matched

via propensity score adjusting for age, gender, BMI, history of spine

fusion, and preoperative ODI scores, leaving 22 in each group. Nine pa-

tients were not matched. Follow-up was at a mean of 13 months in the

open group (range 11 to 33) and 15 months in the MIS group (range 12

to 26 ).

RESULTS: Patients in the open group had more estimated blood loss (681

cc vs 41 cc, p!0.001). Surgical time and hospital stay were shorter in the

MIS group than in the open group (68 mins vs 128 mins; 3.3 days vs 2 days

p! 0.001 for both). The postoperative ODI scores were no different be-

tween groups (47% vs 54%, p 5 0.272).

CONCLUSIONS: Surgical process measures favored the MIS sacroiliac

fusion group, and ODI scores were similar between the groups. Because

the implants used for these procedures make assessment of fusion chal-

lenging with available imaging techniques, we do not know how many pa-

tients’ sacroiliac joints successfully fused, so longer follow-up and critical

evaluation of outcomes scores over time are .




P120. Outcome of Navigated Minimally Invasive Sacroiliac Joint

Fusion: Does Surgical History Matter?

Charles Gerald T. Ledonio, MD1, David W. Polly, Jr., MD2,

Ivana Ninkovic, MPH, MS3, Edward Rainier G. Santos, MD4, Jonathan

N. Sembrano, MD3; 1Minneapolis, MN, US; 2University of Minnesota

Physicians, Minneapolis, MN, US; 3University of Minnesota, Minneapolis,

MN, US; 4Rosemount, MN, US

BACKGROUND CONTEXT: The sacroiliac (SI) joint has been impli-

cated in chronic low back pain for 13%-30% of patients seen in spine prac-

tices. When conservative management fails, SI joint arthrodesis is a viable

alternative. Recent studies have implicated a history of lumbar fusion as a

cause of SI joint pain, which may in turn affect treatment outcomes.

PURPOSE: This study examines the effect of low back surgery history on

SI joint fusion outcomes.

STUDY DESIGN/SETTING: Retrospective review of consecutive case

series.

ssible referenced figures and tables. Authors are responsible for accurately

status at time of abstract submission.




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