Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S 57S

the iliac crest is often a large quantity resulting in a high donor site morbidity.The use of demineralized bone matrix (DBM) as an autograft “extender”for the limited supply of autologous bone eliminates or reduces the needto harvest large quantities from a secondary surgical site, and thus reducesdonor site morbidity. A new demineralized bone matrix, DBX Putty,was used in this study.PURPOSE: The objective of this study is to prospectively compare theresults of the DBX Putty plus autograft to autograft alone in a randomizedcontrolled series of patients undergoing posterolateral fusion.STUDY DESIGN/SETTING: Multi-centered prospective randomized out-come study at nine study centers in the USA. All centers were approvedby the IRB at the institution for participation in the study.PATIENT SAMPLE: One hundred forty patients have undergone instru-mented posterolateral fusion between March 2001 and July 2004. Onehundred and three patients are active until 12 and 24 months. Fortyfive patients in the autograft plus DBX Putty group, (1:1 volumetric ratio)and fifty eight patients are in the autograft group.OUTCOME MEASURES: Pain, function and quality of life was evaluatedpreoperatively, at 6, 12, and 24 months using the VAS and SF-36 and Oswes-try Disablity Questionnaire.METHODS: Inclusion/Exclusion criteria included degenerative disc dis-ease with no more than two levels to be fused between L2-S1. There are66 males and 70 females. Average age is 52. Autograft was harvested fromposterior spinal elements and the iliac crest. Pedicle screws and rods wereused. Study endpoints include evaluation of fusion and outcome measures.Fusion was measured on Flexion/Extension radiographs at 12 and 24months and the Lenke scale. All radiographs were read by a blinded indepen-dent radiologist. Secondary endpoints are pain, function and qualify of life.RESULTS: Fusion rates for both groups were comparable at 12 and 24months. 82 patients are at 12 months and 52 patients are at 24 months.The results of the Lenke scale revealed 66% of the levels in the autograftalone group were solid and 65% of the levels in the DBX group weresolid. Flexion/Extension measurements revealed 81% fusion in the autograftgroup and 82% in the DBX group. Hardware was intact at all levels forboth groups. The average amount of DBX plus autograft was used was 16cc of DBX and 16 cc of autograft. In the autograft alone group, the averageamount of autograft was 27 cc. The autograft group experienced a 71%increase in pain at the donor graft site and the DBX group experienced a60% increase in pain at the donor site. There is an overall improvementrate in the Oswestry Disability of 75% for both groups. The SF-36 andVAS report an overall improvement of 90% for both groups in painand quality of life. There were no neurologic complications. There are 6surgical interventions related to hardware removal and 2 for pseudoarthrosis.The complication rate is 0.04%. Patient satisfaction was 88% in the DBXgroup and 77% in the autograft alone group.CONCLUSIONS: Fusion rates for both groups are comparable. The pre-liminary analysis of the outcome data reveals positive outcomes when usingDBX, as a bone graft extender for posterolateral fusion and is comparableto autograft used alone.DISCLOSURES: FDA device/drug: DBX, demineralized bone matrix.Status: Approved for this indication.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.111

Thursday, September 29, 20055:40–6:40 PM

SIPP 1: Total Disc Replacement Humans

5:40110. MAVERICK total disc replacement: a review of 12-month datafrom five investigational centersMatthew F. Gornet, MD1, Hallet H. Mathews, MD2, J. Kenneth Burkus,MD3, Donald R. Johnson, II, MD4, Kevin A. Rahn, MD5; 1The

Orthopedic Center of St Louis, St. Louis, MO, USA; 2Mid-Atlantic SpineSpecialists, Richmond, VA, USA; 3The Hughston Clinic, Columbus, GA,USA; 4Carolina Spine Institute, Mt. Pleasant, SC, USA; 5Fort WayneOrthopaedics, LLC, Fort Wayne, IN, USA

BACKGROUND CONTEXT: The gold standard of treatment for lumbardegenerative disc disease is surgical arthrodesis. Total disc arthroplastyprovides an alternative to spinal fusion that restores disc height and motion,potentially avoiding adjacent level degeneration. With multiple disc prosthe-ses expected to be available in the near future, surgeons will scrutinize closelythe opportunity for both short-term clinical success and long-term healthof adjacent levels. This is the first study to report clinical results of theMAVERICK Total Disc Replacement (Medtronic Sofamor-Danek).PURPOSE: To examine the 1-year clinical results from five surgeon inves-tigators participating in the FDA Investigational Device Exemption (IDE)study of the MAVERICK Total Disc Replacement used to treat patientswith lumbar degenerative disc disease.STUDY DESIGN/SETTING: A prospective, randomized controlledmulticenter study.PATIENT SAMPLE: We reviewed preoperative through 12-month dataat five participating centers from 64 patients treated with MAVERICK.Inclusion criteria included patients with single-level disc disease (L4-L5or L5-S1) who had not previously received surgical treatment at the involvedlevel (prior laminotomy and discectomy were not excluded), and whofailed to improve with conservative treatment for�6 months. Patients(46% M, 54% F) with a mean age of 40.0 years (range 18–64) included24.5% seeking workers’ compensation.OUTCOME MEASURES: All patients were evaluated clinically beforesurgery, and at 1.5, 3, 6, and 12 months after surgery. Clinical outcomeswere assessed using Oswestry Low Back Pain Disability Questionnaire,neurological status, short form SF-36, and back and leg pain questionnaires.METHODS: Patients in the IDE study were randomized using a 2:1 ratioto the investigational group, receiving the MAVERICK. Control patientsreceived the LT-CAGE with INFUSE Bone Graft. All patients were treatedusing an open anterior approach. We assessed the clinical outcomes of 64patients from the investigational group who had completed 12 monthsfollow-up.RESULTS: Mean operative time was 1.7 hours and mean blood loss was244.2 cc. Average hospital stay was 2.2 days. At 12 months, the meanOswestry score was 20.2, an improvement of 34.9 points or 63.9% (p�.001)versus preoperative scores. Oswestry scores showed statistically significantimprovement and sequentially better outcomes at all measured time intervalsstarting at 6 weeks. The mean SF-36 (PCS) score at 12 months was 43.3,an improvement of 16.1 points vs. preoperatively (p�.001). Back and legpain scores also showed significant (p�.001) improvement and successivelybetter results versus preoperatively at all time intervals.CONCLUSIONS: The clinical outcomes of 64 patients at five participatingcenters demonstrate success at the 1-year postoperative interval in achiev-ing statistically significant improvements in self-reported pain and disabilitymeasures. MAVERICK Total Disc Replacement is a promising alternativeto spinal fusion for the treatment of lumbar degenerative disc disease.DISCLOSURES: FDA device/drug: MAVERICK Total Disc Replace-ment. Status: Investigational/not approved.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.112

5:46111. Analysis of total disc replacement in post-discectomy patientsand comparison to patients with no previous lumbar spine surgeryMichael Leahy, MD1, Jack Zigler, MD1, Donna Ohnmeiss, PhD2,Barton Sachs, MD1, Ralph Rashbaum, MD1; 1Texas Back Institute,Plano, TX, USA; 2Texas Back Institute Research Foundation,Plano, TX, USA

Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S58S

5:52112. Lumbar disc replacement as salvage procedure afterfusion surgeryUlrich Hahnle, MD, Ian Weinberg, MD; University of theWitwatersrand, Johannesburg, Gauteng, South Africa

BACKGROUND CONTEXT: Lumbar disc replacement with a moderntype articulating disc prosthesis started in 1984 with the first implantationof the Charite SB I prosthesis. Since then other, easier implantable discshave been developed (Prodisc, Maverick, Centurion). The indications ofthe procedure remain controversial despite over 16,000 lumbar disc implan-tations worldwide.PURPOSE: Failed fusion patients are difficult to treat. A subgroup of 18patients is analyzed who received lumbar disc replacement adjacent toprevious postero-lateral instrumented fusions and have a minimal follow-up of 1 year.STUDY DESIGN/SETTING: An ongoing uncontrolled, single center pro-spective study involving to date 192 patients with 253 lumbar disc replace-ments. Twenty-three patients had a previous lumbar fusion operation.PATIENT SAMPLE: Of the 23 patients with fusion operations prior to theindex procedure 18 patients had a minimal follow-up of 1 year. 7 patientshad a junctional disc replacement using a Charite disc prosthesis and subse-quently 11 patients using aKineflex lumbar disc prosthesis. The average age was48.8 years (33–63 years). There were 8 female and 10 male patients inthis subgroup. All patients had a significant flat back deformity of theirlumbar spine before the index operation. All patients presented with SI-joint pain and 17 of the 18 patients with symptoms of spinal stenosis.OUTCOME MEASURES: Clinical and radiological evaluation was per-formed during follow-ups. The patient satisfaction with the treatment andthe functional outcome of the treatment were regularly evaluated by useof our own questionnaire including pain score, patient satisfaction, andreturn to work’ data as well as the Oswestry Disability Index for back pain.METHODS: Out of 192 prospectively studied patients who received 253lumbar disc replacements of 2 different models, 23 patients had previouspostero-lateral fusions of 1 to 4 lumbar segments. The index surgery

BACKGROUND CONTEXT: Historically, discogenic back pain resultingfrom a discectomy has been treated successfully with spinal fusion. How-ever, with fusion procedures comes the nearly inevitable abnormal stress andultimate degeneration at adjacent segments. This can ultimately necessitatefuture surgery. This is especially true in younger, active patients. Withthe advent of artificial disc replacement surgery, a potential solution to thisproblem is available. Studies have shown disc replacement surgery to haveat least equal clinical outcomes compared with interbody fusion. With amotion-sparing procedure such a disc replacement surgery, less stress andultimately less degeneration potentially occurs at adjacent segments.PURPOSE: To evaluate the outcomes of total disc replacement proceduresperformed in patients having undergone microdiscectomy at the involveddisc space in the past.STUDY DESIGN/SETTING: Review of patients having undergone arti-ficial disc replacement after microdiscectomy at this institution as par-ticipants in an FDA IDE (Prodisc, Synthes Spine) trial were included inthe study population.PATIENT SAMPLE: Patients having been randomized into the artificialdisc arm of the FDA IDE trial as well as having undergone a discectomyprocedure with a minimum of 2 year follow-up. Patients with previousprocedures such as IDET or Neucleoplasty were excluded (n�15).OUTCOME MEASURES: The outcome measures used in the study werea visual analog scale (VAS) assessing pan, Oswestry Disability Index, andpatient satisfaction.METHODS: A review of all patients with a history of discectomy procedurehaving undergone artificial disc replacement at the same level was under-taken. All data were gathered according to the protocol preoperatively andat 6 weeks, 3, 6, 12, 18, and 24 months. Oswestry, Visual Analog Scales,and 24-month satisfaction scores were obtained from the preexisiting database on these patients at the aforementioned intervals. These patients werecompared with the subgroup who had no previous lumbar spine surgery.RESULTS: The post-discectomy patients were improved based on VASand Oswestry scores at all follow-up periods. They also reported a highlevel of satisfaction at the 24 month follow-up (mean score 8.2 on a scaleof 10). As seen in Figure 1, at no time period was there a significantdifference between the post-discectomy patients and the patients who hadno previous surgery. In the subgroup of patients with no prior surgery, themean satisfaction score was 8.0. Mean VAS scores in both groups improvedsignificantly at all follow-up periods. At no time was there a significantdifference between the two groups.CONCLUSIONS: TDR appears to be a viable treatment for patients whohave previously undergone discectomy. They improved significantly andwere highly satisfied with their results. The outcomes in this subgroup ofpatients were similar to those among patients with no previous lumbarspine surgery.

Fig.

DISCLOSURES: FDA device/drug: ProDisc. Status: Investigational/notapproved.CONFLICT OF INTEREST: Author (JZ) Consultant: Synthes Spine.;Author (JZ) Stockholder: Author owns minimal amount of stock in SynthesSpine.; Author (JZ) Other: Author has received funding for travel to lectureabout artificial discs.

doi: 10.1016/j.spinee.2005.05.113

1.