however, due to very limited comparative data, the clinical efficacy of this

techniques remains unproven. Furthermore, due to concerns such as the

learning curve, potential for increased complications and increased cost,

MIS techniques have not been widely adapted or accepted within the sur-

gical spine community.

PURPOSE: The primary objective of this study was to compare patient

reported outcomes (PRO) following MIS or Open fusion for

spondylolisthesis.

STUDY DESIGN/SETTING: A multicentered retrospective cohort study

of prospectively collected data was performed.

PATIENT SAMPLE: Consecutive patients from academic spine centers.

OUTCOME MEASURES: The primary clinical outcome measure was

change in ODI at 1 year. The secondary measures were pain scores and

SF-36 PCS/MCS.

METHODS: One level instrumented fusions for low grade (I-II) spondy-

lolisthesis from 3 centers, using either a posterior MIS (2 centers: TLIF-

n559) or Open technique (2 centers: TLIF-n543/posterolateral-n587),

with a minimum of 1 year follow-up and baseline patient reported out-

comes (PROs) were compared.

RESULTS: As shown in table 1, both groups demonstarted significant

clinical improvement, however, there were greater improvements in the

MIS compared to Open group in ODI and PCS at 1 and 2 years. Using

ODI as the dependent variable, linear regression demonstrated that MIS,

revision status and baseline PRO were significant factors at one year and

MIS and baseline PRO at 2 years. Age, sex, BMI, co-morbidity, type of

spondylolisthesis (degenerative or isthmic) and complications did not af-

fect ODI. Significantly more patients (p!0.05) reached the minimum clin-

ically important difference in the MIS group at 6 m for back (81 vs 62%)/

leg (88 vs 65%) pain; at 1year for leg pain (83 vs 60%), ODI (72 vs 52%)

and PCS(78 vs 59%); and 2years for ODI (82 vs 64%) and PCS (85 vs

59%). Significantly more patients (p!0.05) reached the substantial clinical

benefit in the MIS group at 6 m for back (75 vs 49%)/leg (84 vs 56%) pain,

and PCS (66 vs 46%); at 1year for leg pain (73% vs 42%), ODI (62 vs

42%) and PCS (76 vs 54%); and 2year for ODI (68 vs 47%) and PCS

(82 vs 55%).

CONCLUSIONS: In this multicentered cohort study, the MIS technique

independently demonstrated superior outcomes at 1 and 2 years postoper-

atively compared to open fusion for spondylolishtesis. Based on the results

of this study, MIS fusion for spondylolisthesis, should be considered a vi-

able surgical management option. Further follow-up with increased patient

numbers and participating centers are required to further validate the gen-

eralizability of these findings.

Note: * p<0.01 for MIS vs. Open.

VAS Back VAS Leg ODI PCS MCS

MIS Open MIS Open MIS Open MIS Open MIS Open

6 month post-op Δ

(MIS n=43/Open n=89)3.8 3.2 5.1* 3.3 19.8 18.6 10.9 7.6 3.1 3.5

1 year post-op Δ

(MIS n=53/Open n=104)3.9 3.2 4.5* 2.8 25.1* 16 12.1* 7.3 4.8 4.2

2 year post-op Δ

(MIS n=34/Open n=94)3.8 3.1 2.9 2.5 25.4* 18.2 12.5* 6.7 6 3.2

Baseline

(MIS n=59/Open n=126)7.1 7.6 6.3 7.4 47.2 50.6 30.6 28.6 45.2 38.5

Table.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2009.08.366

P107. Recurrent Back and Leg Pain and Cyst Reformation after

Surgical Resection of Spinal Synovial Cysts: Systematic Review of

Reported Post-Operative Outcomes

Scott Parker, BASC, Matthew McGirt, MD, Risheng Xu, MA,

Mohamad Bydon, MD, Ali Bydon, MD; Johns Hopkins University,

Baltimore, MD, USA

BACKGROUND CONTEXT: With improvements in neurological imag-

ing, there are increasing reports of symptomatic synovial cysts of the spine.

Surgical excision has been recognized as the definitive treatment for symp-

tomatic juxta-facet cysts. However, the role for concomitant fusion and the

incidence of recurrent back pain and recurrent cyst formation remain

unclear.

PURPOSE: To review all published studies to date reporting outcomes of

synovial cyst excision with and without spinal fusion to determine the cu-

mulative incidence of: 1) post-operative symptomatic relief 2) recurrent

back and leg pain after cyst resection and decompression and 3) synovial

cyst recurrence.

STUDY DESIGN/SETTING: Systematic review of the literature.

PATIENT SAMPLE: All published manuscripts that have reported out-

comes following surgical management of spinal synovial cysts.

OUTCOME MEASURES: Cyst recurrence, re-operation, Macnab, Prolo,

or Stauffer pain scales.

METHODS: We performed a systematic literature review of all papers

published between 1970-2009 reporting outcomes following surgical man-

agement of spinal synovial cysts.

RESULTS: Eighty-two published studies encompassing 799 patients were

identified and reviewed. Five hundred seventeen (64.7%) patients pre-

sented with radicular pain and 335 (41.9%) with back pain. The most com-

mon spinal level was L4-5 (70.5%), and only 17 (2.2%) and 9 (1.2%)

reported synovial cysts were cervical or thoracic, respectively. Seven hun-

dred eighteen (89.9%) patients were treated with surgical excision alone,

while 81 (10.1%) received concomitant spinal fusion. Seven hundred

twenty-five (90.1%) patients experienced complete resolution of their back

or leg pain following surgery, Table 1. By a mean follow-up of 30.2

months, back and leg pain recurred in 111 (14%) patients. Forty-three

(5.4%) patients required re-operation, of which the majority (n526) re-

quired fusion for correction of spinal instability and mechanical back pain,

Table 2. Same level synovial cyst recurrence occurred in 12 (1.7%) pa-

tients after decompression alone but has been reported in no (0%) patients

after decompression and fusion, Table 3.

CONCLUSIONS: Surgical decompression results in symptomatic resolu-

tion in the vast majority of patients; however, recurrent back pain occurs in

14% of patients. Cyst recurrence occurs in less than 2% of patients and has

never been reported to occur after cyst excision with concomitant fusion.

The incidence of mechanical back pain following decompression alone

and lack of cyst recurrence following concomitant fusion reported here

supports the need to investigate the value of fusion of the involved motion

segment in the treatment of symptomatic synovial cysts of the spine.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2009.08.367

P108. Treatment Patterns and Costs of Lumbar Spine Surgeries in

a US Hospital Setting

Bin Zhang, MD, MSC1, Joseph Menzin, PhD1, Mark Friedman, MD1,

Rick Defriesse, MED1, Christina Duczakowski, BA1, Ryan Graver, MPH2;1Boston Health Economics, Inc., Waltham, MA, USA; 2Zimmer, Inc.,

Edina, MN, USA

BACKGROUND CONTEXT: An estimated 50 million individuals in the

US suffer from lower back pain due to spinal disc degeneration, and more

than 450,000 spine fusion surgeries are performed in the US each year. De-

spite the high prevalence of this disease and significant numbers of inva-

sive surgical treatment interventions, hospital data on treatment patterns

and related costs for spine fusion surgery are relatively limited.

PURPOSE: The three main purposes of this study are to: 1) examine treat-

ment patterns of lumbar fusion surgery; 2) estimate costs of hospitalization

among patients who received a lumbar fusion surgery; 3) assess predictors

of hospitalization costs associated with lumbar fusion surgery.

STUDY DESIGN/SETTING: Retrospective database analysis.

PATIENT SAMPLE: Patients who received a lumbar fusion surgery in 29

US institutions between January 2006 and December 2006.

169SProceedings of the NASS 24th Annual Meeting / The Spine Journal 9 (2009) 1S-205S