Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S 105S

difficile occurred. VAS pain scores, pain medication requirements, andOswestry scores showed improvement in 80% of patients. More than half(68%) of the patients returned to their preop student/retired/work status.Deformity: No screws pulled out of bone during the reduction process. Adultand adolescent scoliosis were corrected 72%. Kyphosis was fully correctedand isthmic spondylolisthesis at least partly reduced in all cases.CONCLUSIONS: Many implant systems require rod contouring or offsetconnectors to assemble a construct. This can present a challenge even fordegenerative cases. For deformity, currently available implants rely oncompression and distraction along the rod for correction. Direct lateraltranslation of a vertebra is only possible with a sublaminar wire or cable.The unique pivoting post design of the MPA screw is a considerable technicalimprovement, allowing unlimited variability in screw placement with littleneed for rod contouring or offset connectors. Long-Post MPA screws allowprecise controlled deformity correction with the ability to adjust vertebralposition in multiple planes. This study presents biomechanical testing and2 year clinical results using a new multi-planar adjustable screw systemfor instrumented spine fusions. MPA screws allowed easy rod assemblyregardless of screw orientation or position. The deformity reduction capabil-ity allowed fine control and application of reduction forces to correctscoliosis, kyphosis, and spondylolisthesis. Our series suggests that reliableclinical outcomes can be expected, with easy rod assembly and minimalneed for rod contouring.DISCLOSURES: Device or drug: Multi-Planar Adjustable screw. Status:Approved for this indication.CONFLICT OF INTEREST: Author (DC) Consultant: Consultant ondevelopment of MPA Screw; Author (DC) Speaker’s Bureau Member:Medtronic Sofamor Danek (MSD); Author (DC) Other: Unrestricted grantrecipient; Authors (MMM) Consultant: Employee of MSD; Author (MMM)Stockholder: (MSD); Author (MMM) Board Member: Employee (MSD);Author (DB) Other: Employee (MSD).

doi: 10.1016/j.spinee.2004.05.213

P79. Outcome differences for primary and recurrent disc excisionpatients treated by a single surgeonNitin Bhatia, MD1, Mark Brown, MD, PhD1, , Bobby Tay, MD2,Kathleen Brookfield, MPH1; 1University of Miami, Miami, FL, USA;2University of California, San Francisco, San Francisco, CA, USA

BACKGROUND CONTEXT: A primary cause for reoperation followingsurgery for a herniated lumbar disc is recurrent disc herniation. Outcomesafter reoperation for recurrent herniation are felt to be inferior to those ofprimary excision.PURPOSE: The objective of this paper was to compare the clinical resultsof patients who underwent first time disc excision surgeries with those whohad recurrent disc excisions treated by a single surgeon.STUDY DESIGN/SETTING: Twenty seven consecutive patients withrecurrent herniated lumbar discs were retrospectively reviewed. Clinicaldata and surveys regarding pain, numbness, tingling, and walking tolerancewere collected. A matched cohort of patients with primary herniated discswas created, and similar data obtained.PATIENT SAMPLE: Twenty seven patients who underwent first timedisc excision were retrospectively matched with 27 consecutive patientswho underwent repeat disc excision surgery by the same surgeon. Elevenpatients in each group suffered L5–S1 disc herniation, while 16 suffered L4–L5 disc herniations. None of these patients were fused. A standard surgicalprocedure (laminotomy and discectomy) was performed in all cases by thesame surgeon. Primary disc excision patients were followed for an average of39 months and repeat disc excision patients were followed for an averageof 24 months.OUTCOME MEASURES: Patients were assessed for improvement inleg and back pain, numbness, weakness, and walking tolerance at lastfollow-up, using data obtained from the patients’ medical records, clinicvisits, and telephone interviews.METHODS: Pre-operative and post-operative data was collected for bothpatient groups. The data was evaluated for differences within the groupsand between the two groups.

RESULTS: Eighty-five percent of patients who had primary discectomyexpressed a satisfactory result compared to 60% satisfactory results inpatients who had repeat discectomy. In addition, residual or new onsetback pain was more common in the recurrent disc excision group. First timedisc excision patients exhibited a significant improvement in numbnesspost-operatively (p�0.0486), while recurrent disc excision patients did not.A significantly greater number of first time disc excision patients couldwalk more than two blocks compared to recurrent disc excision patients(p�0.0426). The number of primary disc excision patients experiencing post-operative weakness compared to pre-operative weakness was unchanged.CONCLUSIONS: Compared to patients treated after primary discectomy,a greater number of patients with recurrent herniated discs suffered fromback and leg pain and demonstrated significantly poorer walking tolerance atfollow-up. Patients with recurrent disc herniations experienced less neurologicrecovery and were less satisfied with surgical results of repeat discectomycompared to first-time disc excision patients. In this study evaluating patientstreated by a single surgeon, patients with recurrent herniated discs had inferiorresults in multiple categories than did patients with primary herniated discs.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No Conflicts.

doi: 10.1016/j.spinee.2004.05.214

P24. Kyphoplasty comparable results for vertebral fractures inpatients with multiple myeloma and osteoporosisJoseph Lane1, Susan Bukata, MD1, Jason Koob1, Richard Hong, BS1,Ruben Niesvizky, MD2, Roger Pearse, MD3, David Siegel, MD4;1Hospital for Special Surgery, New York, NY, USA; 2Cornell UniversityMedical College, New York, NY, USA; 3Rockefeller University, NewYork, NY, USA; 4Hackensack Medical Center, Hackensack, NJ, USA

BACKGROUND CONTEXT: Patients with multiple myeloma or osteo-porosis often experience vertebral compression fractures and a secondarykyphosis that results in pain and functional disability.PURPOSE: Do patients with vertebral compression fractures due to osteo-porosis or multiple myeloma experience equivalent improvements in painand function following kyphoplasty?STUDY DESIGN/SETTING: Prospective, Case matched, Hospital forSpecial Surgery.PATIENT SAMPLE: 26 consecutive patients with multiple myelomaand vertebral fractures and 52 age, fracture number, and gender matchedosteoporosis patients who underwent unipedicular kyphoplasty balloon re-duction and stabilization with PMMA.OUTCOME MEASURES: general Oswestry back questionnaire.METHODS: We used kyphoplasty, the minimally invasive procedure uti-lizing balloon tamps, to reduce these compression fractures in both popula-tions with equivalent pain relief and improvement in functional results. Allpatients were evaluated prior to treatment and post-operatively with thevalidated general Oswestry back questionnaire.RESULTS: By Oswestry analysis for the myeloma patients, the averagepre-op score was 49.54 and the average post-op score was 33 with anaverage improvement of 16.54 (p�0.001). For the osteoporosis patients, theaverage Oswestry pre-op score was 48.62 and the average post-op score was34.96 (p�0.001). In both groups, the enhanced function was greatest forpatients with the poorest pre-op Oswestry scores and of little improvementfor patients with initial scores better than 50. In the myeloma patients, an averageheight restoration of 29.83 (p�0.001) and 39.78 (p�0.001) was achievedin the anterior and medial vertebral body regions, respectively, while in theosteoporosis patients, the average height restoration of 31.35 (p�0.001) anteriorand 54.43 (p�0.001) medial was achieved. While the degree of vertebral bodyheight restoration is significantly superior in the patients with osteoporosis(p�0.8 anterior, p�0.03 medial), it does not appear to be a dominant featurein determining the degree of pain relief and functional improvement experiencedby the patient. No patients experienced a major complication. Kyphoplasty hasproven to be safe and comparably efficacious in treating vertebral compressionfractures secondary to either osteoporosis or myeloma.

Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S106S

following segmental posterior spinal instrumentation and fusion ending ateither T12 or L1.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No Conflicts.

doi: 10.1016/j.spinee.2004.05.216

P74. Early restoration of bone following vertebroplasty using a highstrength injectable calcium sulfate bone graft substitute comparedto polymethylmethacrylateThomas Turner, Robert Urban, Michael Tomlinson, Deborah Hall,

CONCLUSIONS: Kyphoplasty has proven to be safe and comparablyefficacious in treating vertebral compression fractures secondary to eitherosteoporosis or myeloma.DISCLOSURES: Device or drug: Kyphon Balloon Tamp. Status: Approv-ed for this indication. Device or drug: Polymethylmethacrylate (PMMA).Status: Not approved for this indication.CONFLICT OF INTEREST: Author (JL) Consultant: Kyphon; Author(JL) Speaker’s Bureau Member: Kyphon; Author (JL) Grant ResearchSupport: Kyphon

doi: 10.1016/j.spinee.2004.05.215

P23. Thoracolumbar junctional analysis in patients fixed to T12 vsL1 in adolescent idiopathic scoliosis: is there any difference?Yong-Jung Kim1, Lawrence Lenke1*, Keith Bridwell2, Junghoon Kim,MD2, Samuel Cho2; 1Washington University in St. Louis, St. Louis, MO,USA; 2Washington University Medical Center, St. Louis, MO, USA

BACKGROUND CONTEXT: Is there any difference in the distal junc-tional change between fusions ending to T12 vs L1 as the lowest instru-mented vertebra (LIV) in adolescent idiopathic scoliosis (AIS) undergoingsegmental posterior spinal instrumentation?PURPOSE: To compare the distal junctional change between fusions toT12 vs L1 as the lowest instrumented vertebra (LIV) in adolescent idiopathicscoliosis (AIS) undergoing segmental posterior spinal instrumentation.STUDY DESIGN/SETTING: A retrospective chart and X-ray review.PATIENT SAMPLE: 115 patients.OUTCOME MEASURES: Radiographs.METHODS: 39 AIS patients underwent a posterior spinal fusion (PSF)with a T12 LIV (T12 group) were compared to 76 patients who underwenta PSF with a L1 LIV (L1 group). Both groups were well matched accordingto the age at surgery, Risser sign, average follow-up, and distal fusion levelwith reference to the neutral vertebra. No revision or anterior cases wereincluded in this study. Radiographic data on these 115 AIS patients witha minimum 2-year postoperative follow-up was collected and analyzedaccording to: LIV with reference to the stable vertebra (SV) and lowerend vertebra (LEV), sagittal LIV-horizontal angle, sagittal disc angle be-neath the LIV, T5–T12 Cobb angle, and C7-sagittal sacral plumb on preop-erative, early postoperative and 2-year follow-up standing long cassetteradiographs. Additional measurements used for analysis included coronalmajor Cobb angle, LIV-horizontal angle, and disc angle beneath the LIV.Abnormal distal junctional kyphosis (DJK) was defined by the distal junc-tion disc angle between the lower end plate of the lowest instrumentedvertebra and the upper end plate of infra-adjacent vertebra, which were atleast 5 degrees greater than the preoperative measurement and at least 5degrees greater than the normal disc angle.RESULTS: Both groups demonstrated similar coronal major Cobb anglechanges (T12 group; preop. 58� and final FU 35� vs 57� and 33� respectivelyin the L1 group) (p�0.149). LIV-horizontal (LIV-H) angle demonstratedsimilar changes (23� to 13� in the T12 group and 19� to 11� in the L1group, p�0.197). Disc angle beneath the LIV (LIV-D) demonstrated similarchanges ( 6.9� to 3.7� in the T12 group and 7.3� to 2.8� in the L1 group,p�0.459). The T12 group demonstrated increased sagittal Cobb anglechanges for T5–T12 (5.0� increase in the T12 group and 1.5� decrease inthe L1 group, p�0.005) and decreased T12-S1 angle changes at final followup (2.9� decrease in the T12 group and 2.41� increase in the L1 group,p�0.050). Both groups demonstrated similar sagittal Cobb angle changesin LIV-S1 angle (1.5� decrease in the T12 group and 0.7� decrease in theL1 group, p�0.751). Both groups demonstrated similar sagittal Cobbangle changes in LIV-D angle (�3.1� to 0� in the T12 group and �5.5�

to �1� in the L1 group, p�0.136). The average discheight change beneath theLIV demonstrated similar changes (0.6mm decrease in the T12 group and0.7mm decrease in the L1 group). The incidence of DJK defined was 10cases (2/ 39, 5% in the T12 group and 8/76,11% in the L1 group) (p�0.324).No patient complained of symptoms related with DJK.CONCLUSIONS: The incidence of DJK and distal junctional changes didnot demonstrate any significant differences in adolescent idiopathic scoliosis

Howard An, MD, Gunnar Andersson, MD; Rush University MedicalCenter, Chicago, IL, USA

BACKGROUND CONTEXT: The use of calcium phosphate cementsin vertebroplasty offers initial strength, early osseointegration, and thepossibility of being replaced by bone over the long term (1). A new high-strength CaSO4 cement promises faster resorption and earlier restorationof bone.PURPOSE: The purpose of this study was to determine if the new cementwould be effective in early restoration of a large vertebral body defect ina canine vertebroplasty model.STUDY DESIGN/SETTING: Vertebroplasties were performed at L1 andL3 in 6 mature hounds (27 to 34 kg), and studied for 8 wks (N=1) and 13wks (N=5). Defects of reproducible size and location were created throughthe lateral vertebral body wall using custom instrumentation, resulting ina large central defect, representing 3/5 the length, 1/2 the height, and 3/4of the width of the body. At one level, the defect was injected using asyringe with 1.5 cc of high-strength vacuum mixed CaSO4 cement (Mini-mally Invasive Injectable Graft, MIIG X3 HiVisc, Wright Medical). Theother defect was injected with the same volume of vacuum mixed polymeth-ylmethacrylate (PMMA) containing BaSO4.PATIENT SAMPLE: Not applicable.OUTCOME MEASURES: Not applicable.METHODS: Radiographs were obtained pre- and postoperative and at 2,4, 6, 8 and 13 wks. Specimen radiographs, CT scans, and serial, axialstained sections of the vertebrae were evaluated for bony restoration of thedefect, reaction to residual cement, and potential effects on the spinal cord.RESULTS: There were no neurological deficits, fractures, or infections.The cements mixed and injected easily. Radiographically, the injectedmaterials completely filled the defects, intruding into the surrounding tra-becular bone without extrusion through the endplates. Initially, the radio-densities of PMMA and CaSO4–injected sites were similar and greater thanthe surrounding bone. There was progressive resorption of cement andreplacement by new bone at the CaSO4–injected sites. At 2 wks, there wasa decrease in density. By 13 wks CaSO4–injected sites had a density similarto the surrounding bone. The PMMA-injected defects maintained a constantradiodensity throughout the study periods. Intravascular intrusion of injectedmaterial was present in the ventral vertebral sinuses of the spinal canalwith both cements, but there were no histological changes in the spinal cord.The stained sections of vertebrae injected with CaSO4 cement demon-strated complete bony restoration of the defects. The majority of the CaSO4cement had resorbed and was replaced with osteoid and new woven boneat 8 wks and primarily lamellar bone at 13 wks. The little remaining CaSO4was either incorporated into the newly formed bone or was undergoingresorption by osteoclast-like cells. In contrast, there was no apparent resorp-tion of the PMMA, and the material was often separated from the sur-rounding bone by a thin fibrous membrane.CONCLUSIONS: The results of this study indicate that early restorationof a large central vertebral body defect can be achieved using high-strength,injectable CaSO4 cement. Although PMMA cement can be effective inrestoring height and stability to the vertebral body, it does not resorb, andthe long-term effects of a bolus of this material are unknown. Calciumphosphate cements offer a more biological approach with the ability to beslowly resorbed and replaced with new bone over the long term. The earlyresorption and bony restoration of vertebral defects using this new high-strength calcium sulfate cement may be advantageous.