2S Proceedings of the NASS 22nd Annual Meeting / The Spine Journal 7 (2007) 1S–163S

Figure 1. DEXA Scan image and Cobb’s measurment

CONCLUSIONS: Our study indicates that the prevalence of lumbar sco-

liosis in adults is 8.85%. Increasing age was associated with increasing

likelihood of scoliosis while non-white race was associated with reduced

likelihood of scoliosis.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2007.07.006

3. Validation of a ‘‘Minimum Acceptable Outcomes’’ Model for

Outcomes Assessment in Spinal Surgery

Eugene Carragee, MD1, Ivan Cheng, MD2, Mark Wang, MD1; 1Stanford

University, Stanford, CA, USA; 2Stanford School of Medicine, Stanford,

CA, USA

BACKGROUND CONTEXT: Defining clinical ‘‘success’’ after spinal

surgery has proven problematical. Arbitrary benchmarks such as 2 point

improvements on the VAS scale or 10 point improvements by the Oswestry

Disability Index, are frequently within the spontaneous variation of the

condition and often well below patient’s expectations of clinical improve-

ment. Previous studies have described a method to determine the pre-

operatively ‘‘minimal acceptable outcomes’’ as described by patients

having spinal surgery.

PURPOSE: To establish the validity of patient-determined ‘‘minimum ac-

ceptable outcomes’’ as a criteria of surgical success in patients undergoing

spinal surgery.

STUDY DESIGN/SETTING: Validation study of the ‘‘minimum accept-

able’’ outcomes after spinal surgery.

PATIENT SAMPLE: Consecutive cohort of patients having decompres-

sion and / or fusion surgery of the lumbar spine.

OUTCOME MEASURES: Outcomes were assessed using the VAS for

the severity of back and leg pain, ODI, pain medication usage, and work

loss by standard questionnaire. These were compared to post-operative

global satisfaction. Concordance of satisfaction and achievement of

minimum acceptable outcomes was analyzed as a function of baseline

demographic, surgical and psychometric factors.

METHODS: Minimum acceptable outcome (pre-operatively-determined)

and satisfaction (at two years post-operatively) were prospectively studied

in 298 consecutive having lumbar spine surgery. Baseline pre-operative

values were assessed using the visual analog scale (VAS) for the severity

of back and leg pain, the Oswestry Disability Index (ODI), and recorded

a history of pain medication usage, pre-operative symptom duration, work

status and amount of pre-operative work loss on a standard questionnaire.

These subjects were then given standardized forms to complete indicating

minimum-acceptable outcome signifying worst of outcome in each dimen-

sion for which they would undergo surgery. Subjects were then followed

for two years and their outcomes and satisfaction compared to the mini-

mum acceptable outcomes previously determined.

RESULTS: There was a wide variation in what individual patient consid-

ered a ‘‘minimum acceptable outcome’’ for spinal surgery. However, valid-

ity appears to be high as subjects achieving their own ‘‘minimum acceptable

outcome’’ very commonly reported post-operative satisfaction (Positive

Predictive Value586%, CI 82–90%). Conversely, not achieving the mini-

mum acceptable outcome was associated with satisfaction 36% of the cases

(Negative predictive value564%, CI 56–72%). Satisfaction despite failure

to achieve minimum acceptable outcomes was more common in certain

subgroups: baseline factors of psychological distress, worker’s compensa-

tion claims, litigation, and other chronic pain problems at baseline predicted

a dissociation on minimum acceptable outcomes stated at baseline and sat-

isfaction of follow-up (i.e. patients may indicate satisfaction with treatment

even though minimum outcomes were not achieved).

CONCLUSIONS: The ‘‘minimum acceptable outcome’’ method appears

to be a well validated means of defining ‘‘success’’ for most patients hav-

ing spinal surgery. Global ‘‘satisfaction’’ in patients not achieving pre-

operative minimum goals is highly correlated with psychosocial issues

and may indicate that ‘‘satisfaction’’ in these patients is a related to factors

other than functional improvement, return to work or discontinuing pain

medications.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2007.07.007

4. Epidural Application of Particulate Wear Debris: A

Comprehensive Analysis of Ten Different Implant Materials Using

an In-Vivo Animal Model

Bryan W. Cunningham, MSc1, Candace M. Zorn, BS1, Nianbin Hu, MD1,

Nadim Hallab, PhD2, Paul C. McAfee, MD3; 1St. Joseph Medical Center,

Towson, MD, USA; 2Rush University Medical Center, Chicago, IL, USA;3St. Joseph Hospital, Towson, MD, USA

BACKGROUND CONTEXT: N/A

PURPOSE: The effect of particulate wear debris from the bearing sur-

faces of motion preserving spinal implants remains a clinical concern. Us-

ing an in-vivo rabbit model, the current study serves to quantify the neural

and systemic tissue histopathological response, following epidural applica-

tion of ten different types of particulate wear debris used in motion pre-

serving spinal implants.

METHODS: One Hundred New Zealand White rabbits were equally ran-

domized into ten groups (n510 group) based on treatment material: 1)

Sham (control), 2) Stainless Steel 316LVM, 3) Titanium Alloy Ti-6AL-

4V, 4) Cobalt Chrome Alloy, 5) Ultrahigh molecular weight polyethylene

(UHMWPE), 6) Polycarbonate Urethane (PCU), 7) Polyetheretherketone

(PEEK), 8) Polyvinyl Alcohol (PVA), 9) Polyester and 10) Ceramic. The

surgical procedure consisted a midline posterior approach, followed by re-

section of the L6 spinous process and ligamentum flavum at L5-L6 – per-

mitting interlaminar exposure of the dural sac. 4mg (size range 0.3–50

diameter; dosage 300 to 600 million particles) of the appropriate treatment

material was then implanted in dry, sterile format. Five animals from