2. Prevalence of Scoliosis in Adults Age 40 Years and Older: A Study Of 2973 Individuals

The Spine Journal 7 (2007) 1S–163S

Wednesday, October 24, 2007 7:30–8:20 AM General Session: Best Papers 1. MaverickÔ Total Disc Replacement versus Anterior Lumbar Interbody Fusion with the INFUSEÒ Bone Graft /LT-CAGEÒ Device: A Prospective, Randomized, Controlled, Multicenter IDE Trial Matthew F. Gornet, MD1, J. Kenneth Burkus, MD2, Hallett H. Mathews, MD3, Randall F. Dryer, MD4, John Peloza, MD5; 1St. Louis, MO, USA; 2 The Hughston Clinic, Columbus, GA, USA; 3Medtronic Spine and Biologics (formerly of Mid-Atlantic Spine Specialists, Williamsburg, VA), Memphis, TN, USA; 4Austin, TX, USA; 5Center For Spine Care, Dallas, TX, USA

(p!0.001) but also superiority (p50.003) conclusions for TDR (77.2%) versus ALIF (64.2%). CONCLUSIONS: Treatment with the Maverick Disc consistently demonstrated statistical superiority versus fusion on key clinical outcomes including Oswestry, SF-36 PCS, back pain scores, patient satisfaction and Overall Success, resulting in improved physical function, reduced pain, and earlier return to work. This study reconfirms earlier IDE data establishing ALIF using rhBMP-2 with threaded cages as a safe, effective treatment. A randomized trial with this modern fusion technology as control ensured the most rigorous study comparisons, validating the benefits of the Maverick disc for appropriately selected patients. FDA DEVICE/DRUG STATUS: Maverick Total Disc Replacement: Investigational/ Not approved; INFUSE Bone Graft: Approved for this indication; LT-CAGE Lumbar Tapered Fusion Device: Approved for this indication. doi: 10.1016/j.spinee.2007.07.005

BACKGROUND CONTEXT: For patients with degenerative disc disease (DDD), total lumbar disc arthroplasty provides an alternative to fusion designed to relieve persistent discogenic pain and to restore and maintain normal disc height and motion. PURPOSE: This IDE study compares the patient outcomes of lumbar disc arthroplasty using the MaverickÔ Disc with those of anterior interbody fusion with the INFUSEÒ Bone Graft/LT-CAGEÒ Device. STUDY DESIGN/SETTING: A prospective, randomized (2:1), controlled study at 31 centers. PATIENT SAMPLE: 405 investigational (TDR) and 172 control (ALIF) patients with single-level DDD (L4 to S1) and no prior surgical treatment at the involved level (prior laminotomy and discectomy not excluded) were treated after failing conservative care for 6 months. Patient groups were similar in demographics, prior medical conditions, and preoperative clinical measures. OUTCOME MEASURES: Oswestry Disability Index (ODI), SF-36, back and leg pain questionnaires, neurological status, work status, patient satisfaction, and radiographic measurements. METHODS: Study results include clinical and radiographic measures collected preoperatively, and at 1.5, 3, 6, 12, and 24 months for statistical analysis. RESULTS: Mean (TDR/ALIF) operative time (1.8/1.4 hrs.) and blood loss (240.7/95.2 ml) differences were significant (p!0.001); mean hospital stay (2.2/2.3 days) and operative level (73.6/78.5% L5-S1) were not. Oswestry mean score improvement was dramatic for both groups at 12 and 24 months (TDR 33.9/33.8; ALIF 29.0/29.3), surpassing mean ODI improvements reported for all the device treatments in the IDE studies that supported the FDA approvals of the two other lumbar artificial discs. At 24 months, 82.2% of TDR patients reported an ODI improvement of at least 15 points, an FDA-defined measure of success, versus 75.2% for the ALIF group. Statistical superiority over fusion is concluded for MAVERICK mean improvements from pre-op at all follow-up intervals, including 24month ODI (p50.005), SF-36 PCS (p50.010), and back pain scores (p50.027). Both groups also showed significant (p!0.001) improvement in leg pain scores from pre-op. Fusion success was 100% (6, 12, and 24 months) for ALIF patients. TDR disc height and angular motion were maintained postoperatively. TDR patients had fewer serious device-related adverse events. Neurological status was statistically equivalent in the two groups. TDR patients returned to work 21 days sooner in median (p50.038) than ALIF patients. Finally, at 24 months, 86.2% of TDR patients said that they would have the surgery again, vs. 74.5% for the ALIF group (p50.002). Overall Success rates at 24 months – an FDA composite measure and the primary study endpointdsupport not only non-inferiority

2. Prevalence of Scoliosis in Adults Age 40 Years and Older: A Study Of 2973 Individuals Gabor Voros, MD1, Philip Neubauer, MD1, Mohammad Khoshnevisan1, Richard Skolasky, Jr., MA1, John Kostuik, MD2, Khaled Kebaish, MD, FRCS(C)1; 1Johns Hopkins University, Baltimore, MD, USA; 2Leesburg, VA, USA BACKGROUND CONTEXT: Reports on the prevalence of scoliosis in adults vary significantly. Reported prevalence of scoliosis in adults range from 1.9% to 68%. These rates vary depending on what particular definition of scoliosis is used and what patient population is being studied. PURPOSE: Study the prevalence of scoliosis and its relationship with age, race, and gender adult population, greater than 40 years age. STUDY DESIGN/SETTING: Dexa Scan images of 2973 individuals age 40 years and older (Avg 60.8 R540–97), obtained between January 2004 and March 2006 at a university hospital were used to determine the presence of scoliosis using Cobb’s method. PATIENT SAMPLE: 2973 individuals, age 40 years and older (Avg 60.8 R540–97),who received DEXA scans, between January 2004 and March 2006 at a university hospital. OUTCOME MEASURES: Statistical analyses was conducted using SAS system software, version 9.1 and the % match macro developed by Mandrekar & Mandrekar (2004). METHODS: Dexa Scan images of 2973 individuals age 40 years and older (Avg 60.8 R540–97), obtained between January 2004 and March 2006 at a university hospital were used to determine the presence of scoliosis using Cobb’s method. Scoliosis was defined as a curvature of at least 11.00 on lumbar spine DEXA Scan images. Curves were classified as mild (11.00 –24.49 ), moderate (24.50 –44.49 ), and severe (44.50 or greater). Cobb’s angles were measured digitally using the Iconico Screen ProtractorÒ v3.3 and the visual DEXA images of the lumbar spine. Patients with a history of previous lumbar spinal fusion, were excluded from the study. RESULTS: Based on our dataset of 2973 DEXA scan images the prevalence of scoliosis in adults was 8.85%. The prevalence of scoliosis increased almost linearly from the 6th (OR:3.84, 95% CI 2.23, 6.63) to the 8th decade (OR:9.24, 95% CI 4.93, 17.29). African american has half the likelihood of scoliosis (OR:0.45, 95% CI 0.33, 0.60). There was no association between gender and prevalence of scoliosis.

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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 scoliosis 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.

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 dimension for which they would undergo surgery. Subjects were then followed for two years and their outcomes and satisfaction compared to the minimum acceptable outcomes previously determined. RESULTS: There was a wide variation in what individual patient considered a ‘‘minimum acceptable outcome’’ for spinal surgery. However, validity 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 minimum 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 compensation claims, litigation, and other chronic pain problems at baseline predicted a dissociation on minimum acceptable outcomes stated at baseline and satisfaction 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 having spinal surgery. Global ‘‘satisfaction’’ in patients not achieving preoperative 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

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 improvement. Previous studies have described a method to determine the preoperatively ‘‘minimal acceptable outcomes’’ as described by patients having spinal surgery. PURPOSE: To establish the validity of patient-determined ‘‘minimum acceptable outcomes’’ as a criteria of surgical success in patients undergoing spinal surgery. STUDY DESIGN/SETTING: Validation study of the ‘‘minimum acceptable’’ outcomes after spinal surgery. PATIENT SAMPLE: Consecutive cohort of patients having decompression 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

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; 3 St. Joseph Hospital, Towson, MD, USA BACKGROUND CONTEXT: N/A PURPOSE: The effect of particulate wear debris from the bearing surfaces of motion preserving spinal implants remains a clinical concern. Using an in-vivo rabbit model, the current study serves to quantify the neural and systemic tissue histopathological response, following epidural application of ten different types of particulate wear debris used in motion preserving spinal implants. METHODS: One Hundred New Zealand White rabbits were equally randomized into ten groups (n510 group) based on treatment material: 1) Sham (control), 2) Stainless Steel 316LVM, 3) Titanium Alloy Ti-6AL4V, 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 resection of the L6 spinous process and ligamentum flavum at L5-L6 – permitting 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