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P26. Scoliosis correction using a new screw with a pivoting reduction post: biomechanical testing and 2 year clinical results
Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S PURPOSE: Literature suggests that decompressive surgery for degenerative spondylolisthesis should be combined with stabilization. Currently, a fusion procedure is typically performed with inherent disadvantages, possibly contributing to future adjacent level degeneration. Mobile stabilization would be advantageous, allowing more physiological function. The DYnamic NEutralization SYstem for the Spine (Dynesys) is a pedicle screw system for mobile stabilization, consisting of titanium alloy pedicle screws, connected by an elastic synthetic compound controlling motion in any plane. This study evaluated the safety and efficacy of Dynesys to treat degenerative lumbar spondylolisthesis. STUDY DESIGN/SETTING: Prospective multi-center study with a minimum follow-up time of one year. PATIENT SAMPLE: 39 patients requiring surgery for degenerative lumbar spondylolisthesis (including 34 with lumbar stenosis, 3 with degenerative scoliosis, 10 with previous lumbar surgery). The mean age was 65.5 years (38–85), the mean time to follow-up was 35.3 months (range 11.2–61.4). OUTCOME MEASURES: VAS, Oswestry Disability Index, clinical status, radiological assessment. METHODS: This prospective, multicenter study evaluated pre- and postoperative pain, function and radiological data on a consecutive series of 39 degenerative lumbar spondylolisthesis patients . Dynesys was implanted in all patients. In 34 (87%) patients implantation was combined with decompression. RESULTS: Mean pain and function scores, available from 36 of the patients, improved significantly from baseline to follow-up. The mean back VAS score was reduced from 7.4 to 2.6. The mean leg VAS score was reduced from 7.4 to 2.1. Oswestry showed that these patients improved from severe disability (55.2) pre-operatively to minimal disability (19.2) post-operatively. One complication (2.6%) was device-related: 1 misplaced screw was removed. Other events included: 2 dural lesions of which 1 was revised, 1 pedicle fracture during implantation, 1 scar neuroma excised, 1 seroma drained, 1 (resolving) hypesthesia, 1 conservatively treated infection. Radiographic analysis revealed screw halos in 2 patients not affecting outcomes. Additional surgical interventions for adjacent segment stenosis included 2 extensions (5.1%) of Dynesys to additional spinal levels, and 2 device explants (5.1%) with subsequent fusion to additional segments. One of the patients requiring device explantation underwent 2 previous decompression procedures at adjacent levels. CONCLUSIONS: These study results are comparable with those obtained by conventional procedures; however, mobile stabilization is less invasive than most fusion procedures. The natural course of polysegmental disease in some cases necessitates further surgery as the disease progresses. Longterm screw fixation is dependent on correct screw dimension and proper screw positioning. Dynamic neutralization proved to be a safe and effective alternative in the treatment of degenerative lumbar spondylolisthesis, yet it constitutes a less invasive procedure than fusion. DISCLOSURES: Device or drug: Dynesys. Status: Investigational/Not approved. CONFLICT OF INTEREST: Author (TS) Consultant: Dynesys. doi: 10.1016/j.spinee.2004.05.144
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STUDY DESIGN/SETTING: Bioabsorbable implants may possess the ideal characteristics of an interbody fusion device. They provide immediate postoperative stability, but permit controlled load-sharing with time through resorption. PATIENT SAMPLE: Twenty-five consecutive patients underwent a single or two-level TLIF (mean 1.4 levels, total 35 levels) with an absorbable interbody device (and rhBMP-2) and segmental pedicle screw fixation with titanium multi-axial pedicle screws and 5.5mm diameter rods. They were compared to 25 consecutive matched single or two-level TLIF patients (1.3 levels, total 33 levels) who were fixed with titanium vertical cage filled with autograft and the same instrumentation system.(p⫽0.57). OUTCOME MEASURES: Radiographs were evaluated for instrumentation complications, posterior disc height, and evidence of bridging bone in the interbody space. Preoperataive segmental sagittal contour was also evaluated on standing radiographs preoperatively, at immediate postoperative visit, at 3 months, 6 months, 1 year and 2 year follow-up visits. METHODS: This is a consecutive case series (with matched control) with postoperative CT scanning to assess fusion status, postoperative disc height and sagittal contour following instrumented TLIF. There were 25 patients in each group. Group I (absorbable device with rhBMP-2) included 19 males, 6 females at an average age of of 39.5 years (range 23–62), while Group II (titanium vertical cage) included 17 males, 8 females at an average age of 37.4 years (range, 21–58).(p⫽0.45) Plain radiographs were used to compare posterior disc height and sagittal contour, while 3D reconstruction CT scans were used to evaluate fusion status. RESULTS: There was one pseudarthrosis in Group I, noted by implant failure on latest follow-up (34/35 fusion levels, 97.1%), and one pseudarthrosis in Group II (31/33 fusion levels, 93.9%).(p⫽0.14). In Group I, there were 15 single-level and 10 two-level fusions (total 35 levels), while in Group II there were 17 single-level and 8 two-level fusions (total 33 levels). In terms of posterior disc height, Group I was 4.6mm (range, 2.0– 7.8mm) preoperatively, and 8.0 (range, 5.0–10.1mm) postoperatively, or ⫹3.4mm (range, ⫹2.0–6.2mm). For Group II, preoperative disc height was 4.8mm (range, 2.5–8.3mm), while postoperative disc height was 8.3mm (range, 4.6–10.0mm).(p⫽0.34). There was statistically insignificant settling of the Group I absorbable implants (average 0.4mm), compared to Group II (average 0.2mm).(p⫽0.33) For sagittal contour, Group I average preoperative segmental sagittal contour was 4.8 degrees (⫹/⫺ 3.5 degrees) and 8.0 degrees (⫹/⫺ 2.4 degrees) postoperatively. For Group II, preoperative contour was 4.2 degrees (⫹/⫺ 3.0 degrees) and 7.9 degrees (⫹/⫺ 4.0 degrees) postoperatively.(p⫽0.23) CONCLUSIONS: The bioabsorbable implants had a slightly better fusion rate (statistically insignificant, p⫽0.14) with equilavent maintenance of sagittal contour and posterior disc height when compared to vertical titanium cages. DISCLOSURES: Device or drug: Hydrosorb (Medtronic Sofamor Danek). Status: Approved for this indication. Device or drug: Infuse (Medtronic Sofamor Danek). Status: Approved for this indication. CONFLICT OF INTEREST: Author (TK) Grant Research Support: Medtronic Sofamor Danek. doi: 10.1016/j.spinee.2004.05.145
P81. Maintenance of sagittal contour following TLIF with an absorbable interbody device Timothy Kuklo1, Michael Rosner1, David Polly, Jr.2; 1Walter Reed Army Medical Center, Washington, DC, USA; 2University of Minnesota, Minneapolis, MN, USA BACKGROUND CONTEXT: Structure interbody support remains a mainstay in the spinal fusion armamentarium in degenerative disc disease, with multiple reports in the literature on various interbody devices. Maintenance of sagittal contour following absorbable devices has not been reported. PURPOSE: The purpose of this study is to evaluate the sagittal contour following single or multi-level interbody fusion to determine the maintenance of sagittal contour and disc height/foraminal height following TLIF for degenerative disc disease.
P26. Scoliosis correction using a new screw with a pivoting reduction post: biomechanical testing and 2 year clinical results Dennis Crandall, MD1, Matthew M. Morrison, BSME2, Douglas Slaughter, MD1, Douglas Baker, BSME2, PJ Hankins, RN, BSN, ONC1; 1 Sonoran Spine Center, Phoenix, AZ, USA; 2Medtronic Sofamor Danek, Memphis, TN, USA BACKGROUND CONTEXT: A new screw with a 180 degree pivoting reduction post was designed to make spinal deformity correction more finely controlled and technically easy. PURPOSE: Biomechanical and clinical studies were performed to evaluate this new Multi-Planar Adjustable (MPA) screw (510K cleared) in correcting scoliosis in adolescents and adults.
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Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S
STUDY DESIGN/SETTING: Biomechanical testing of the new screwrod construct was conducted using a corpectomy model. A Prospective clinical study was conducted with 2 year patient follow up. PATIENT SAMPLE: Clinically, 32 consecutive patients (30 female, 2 male) average 51 years (15–85 years) were surgically treated for scoliosis with posterior instrumented correction and fusion, and prospectively followed 2 years. Anterior release and fusion was required in 26. There were 11 Degenerative, 16 Adult Idiopathic, and 5 Adolescent Idiopathic scoliosis patients. Surgical indications included curve progression, spinal imbalance, or pain failing ⬎6 months conservative care. OUTCOME MEASURES: Outcomes assessed included pre and post-op VAS pain scores, pain medication records, Oswestry scores, and work status. Radiographs were obtained at 2, 3, 6, 9, 12, 18, and 24 months. METHODS: Surgical Technique: Rods were bent into the desired spinal contour. Hooks or screws were used in the thoracic spine. New MPA screws with long threaded reduction posts were used in the lower thoracic and lumbar spine. The reduction posts had the ability to pivot 180 degrees side to side, allowing easy attachment to the rod. Deformity correction was accomplished by: 1) Direct lateral translation of the spine by incremental tightening the reduction nut on the long post of the MPA screws. This precise and finely controlled reduction force was gradually applied over 20–60 minutes. 2) Manual manipulation of the spine by pushing or pulling the long reduction posts attached to the screws in conjunction with rod derotation. 3) Compression or distraction along the rod. All constructs were crosslinked. Spinal cord monitoring was used in all cases. RESULTS: The biomechanical testing of the new screw-rod construct was similar in strength and rigidity to other commonly used multi-axial screwrod constructs. Adult Idiopathic scoliosis averaged 62 degrees (39–90) corrected 72% to 17 degrees (6–40). Degenerative curves averaged 37 degrees (20–75) corrected 71% to 11 degrees (5–21). Adolescent scoliosis averaged 46 degrees corrected 70% to 14 degrees (12–16). Of the 26 patients with pre-op pain, 24 (92%) showed clinical improvement by decreased pain scores (VAS 6.7 pre, 2.4 post), declining medication use, and improved Oswestry scores. All but 2 patients returned to their pre-op work/ student/retired status. There was one wound infection and two nonunions. There were no implant related complications. CONCLUSIONS: Spinal instrumentation currently available achieves scoliosis correction by hook/screw compression or distraction along the rod and by rod derotation. Direct lateral translation of a vertebra is currently only possible using a sublaminar wire or cable. This study presents biomechanical testing and 2 year follow-up on adult and adolescent scoliosis correction using a unique screw with a threaded reduction post that pivots 180 degrees side to side. This feature allows easy rod assembly and fine control of reduction forces in multiple planes to precisely correct scoliosis in a way not previously possible. Improved control and correction of deformity are anticipated using the MPA screw. DISCLOSURES: Device or drug: Multi-planar adjustable (MPA) screw. Status: Approved for this indication. CONFLICT OF INTEREST: Author (DC) Consultant: Consultant for Medtronic Sofamor Danek; Author (DC) Speaker’s Bureau Member: Speaker’s Bureau for Medtronic Sofamor Danek; Author (DC) Other: Unrestricted eductional grant received from Medtronic Sofamor Danek; Authors (MMM, DB) Consultant: Medtronic Sofamor Danek Employee; Authors (MMM, DB) Stockholder: Medtronic Sofamor Danek Stockholder; Author (DB) Speaker’s Bureau Member: Medtronic Sofamor Danek Employee. doi: 10.1016/j.spinee.2004.05.146 P76. Selection of the lowest instrumented vertebra in thoracic adolescent idiopathic scoliosis Lenke type 1 and 2 following segmental posterior spinal fusion Lawrence Lenke1*, Yong-Jung Kim1, Keith Bridwell, MD2, Junghoon Kim, MD3, Samuel Cho4; 1Washington University in St. Louis, Saint Louis, MO, USA; 2Washington University Medical Center, St. Louis, MO, USA; 3MO, USA; 4Washington University Medical Center, MO, USA
BACKGROUND CONTEXT: The safest lowest instrumented vertebra (LIV) in Lenke type 1 (main thoracic) and 2 (double thoracic) adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion is still controversial. PURPOSE: To determine the safest lowest instrumented vertebra (LIV) in Lenke type 1 (main thoracic) and 2 (double thoracic) adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion. STUDY DESIGN/SETTING: A retrospective chart and radiographs review. PATIENT SAMPLE: 194 patients. OUTCOME MEASURES: Radiographs. METHODS: Radiographic and clinical data on 194 consecutive Lenke type 1 and 2 AIS patients (average age; 14.6 years, range 10.1– 20.7 years) with minimum 2-year follow-up (average 5.6 years; 2–16.7 years) treated with instrumented segmental posterior spinal fusion was collected. All patients were grouped according to the preoperative lumbar modifier (A, B, and C) and LIV instrumentation type (Hook vs pedicle screws). Each group was compared with one another in reference to the stable vertebra (SV), neutral vertebra (NV), and lower end vertebra (LEV) of the major curve on the standing AP radiograph. RESULTS: 110 lumbar A modifier patients demonstrated 32⬚ major Cobb angle correction (59⬚⫹11⬚ to 27⬚⫹12⬚). 58 lumbar B modifier and 26 C modifier patients demonstrated 27⬚ and 25⬚ major Cobb angle correction respectively (60⬚⫹12⬚ to 33⬚⫹10⬚ and 60⬚⫹11⬚ to 35⬚⫹12⬚ respectively). The LIV in lumbar A modifier patients were SV-0.87 vertebrae, NV-0.05 vertebrae, and LEV⫹ 1.42 vertebrae. The LIV in lumbar B modifier patients were SV⫹0.22, NV⫹0.81, and LEV⫹ 1.34 vertebrae. The LIV in C modifier patients were SV⫹0.31, NV⫹0.73, and LEV⫹0.96 vertebrae (p⬍0.001 by SV, p⬍0.001 by NV, and p⫽0.220 by LEV). 146–hook instrumentation group demonstrated 27⬚ major Cobb angle correction (59⬚⫹11⬚ to 32⬚⫹11⬚, 46% correction). 48-pedicle screw instrumentation demonstrated 37⬚ major Cobb angle correction (61⬚⫹14⬚ to 24⬚⫹11⬚, 60% correction). The LIV in the hook group were SV-0.29 vertebrae, NV⫹0.45 vertebrae, and LEV⫹ 1.41 vertebrae. The LIV in the pedicle screw group were SV-0.67, NV-0.13, and LEV⫹ 1.11 vertebrae that demonstrating a definite shorter fusion in the screw group with reference to stable and neutral vertebra (p⫽0.022 by SV, p⫽0.006 by NV, and p⫽0.061 by LEV). CONCLUSIONS: The LIV in lumbar A modifier patient was 1 vertebra cephalad than for those lumbar B or C modifier patients with reference to the SV and NV criteria. The LIV in pedicle screw instrumentation was 0.5 vertebrae shorter than for hook instrumentation with reference to the SV and NV criteria. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.147 P71. Effects of adenovirus expressing twelve different bone morphogenetic proteins on proteoglycan metabolism of the intervertebral disc Yejia Zhang, MD, PhD1, Zhen Li, MD1, Tong-Chuan He, MD, PhD2, Howard An, MD1, Shiwen Song, MD PhD1, Eugene Thonar, PhD1, Gunnar Andersson, MD, PhD1, Frank Phillips, MD1; 1Rush University/ Rush- Presbyterian-St. Luke’s Medical Center, Chicago, IL, USA; 2 University of Chicago, Chicago, IL, USA BACKGROUND CONTEXT: The loss of extracellular matrix proteoglycans is a salient feature of intervertebral disc (IVD) degeneration. Certain bone morphogenetic proteins (BMPs) are known to reverse this process in healthy and diseased IVDs; however the direct administration of the protein in vivo will have a relatively short-lived effect. The delivery of BMPs with gene therapy would allow for a sustained protein expression that could promote disc matrix regeneration. To date there have been no studies directly comparing the abilities of different members of the BMP family to promote extracellular matrix production. PURPOSE: Our goal is to compare the relative activities of adenovirus expressing twelve different BMPs on proteoglycan accumulation by adult bovine IVD cells.
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STUDY DESIGN/SETTING: Bioabsorbable implants may possess the ideal characteristics of an interbody fusion device. They provide immediate postoperative stability, but permit controlled load-sharing with time through resorption. PATIENT SAMPLE: Twenty-five consecutive patients underwent a single or two-level TLIF (mean 1.4 levels, total 35 levels) with an absorbable interbody device (and rhBMP-2) and segmental pedicle screw fixation with titanium multi-axial pedicle screws and 5.5mm diameter rods. They were compared to 25 consecutive matched single or two-level TLIF patients (1.3 levels, total 33 levels) who were fixed with titanium vertical cage filled with autograft and the same instrumentation system.(p⫽0.57). OUTCOME MEASURES: Radiographs were evaluated for instrumentation complications, posterior disc height, and evidence of bridging bone in the interbody space. Preoperataive segmental sagittal contour was also evaluated on standing radiographs preoperatively, at immediate postoperative visit, at 3 months, 6 months, 1 year and 2 year follow-up visits. METHODS: This is a consecutive case series (with matched control) with postoperative CT scanning to assess fusion status, postoperative disc height and sagittal contour following instrumented TLIF. There were 25 patients in each group. Group I (absorbable device with rhBMP-2) included 19 males, 6 females at an average age of of 39.5 years (range 23–62), while Group II (titanium vertical cage) included 17 males, 8 females at an average age of 37.4 years (range, 21–58).(p⫽0.45) Plain radiographs were used to compare posterior disc height and sagittal contour, while 3D reconstruction CT scans were used to evaluate fusion status. RESULTS: There was one pseudarthrosis in Group I, noted by implant failure on latest follow-up (34/35 fusion levels, 97.1%), and one pseudarthrosis in Group II (31/33 fusion levels, 93.9%).(p⫽0.14). In Group I, there were 15 single-level and 10 two-level fusions (total 35 levels), while in Group II there were 17 single-level and 8 two-level fusions (total 33 levels). In terms of posterior disc height, Group I was 4.6mm (range, 2.0– 7.8mm) preoperatively, and 8.0 (range, 5.0–10.1mm) postoperatively, or ⫹3.4mm (range, ⫹2.0–6.2mm). For Group II, preoperative disc height was 4.8mm (range, 2.5–8.3mm), while postoperative disc height was 8.3mm (range, 4.6–10.0mm).(p⫽0.34). There was statistically insignificant settling of the Group I absorbable implants (average 0.4mm), compared to Group II (average 0.2mm).(p⫽0.33) For sagittal contour, Group I average preoperative segmental sagittal contour was 4.8 degrees (⫹/⫺ 3.5 degrees) and 8.0 degrees (⫹/⫺ 2.4 degrees) postoperatively. For Group II, preoperative contour was 4.2 degrees (⫹/⫺ 3.0 degrees) and 7.9 degrees (⫹/⫺ 4.0 degrees) postoperatively.(p⫽0.23) CONCLUSIONS: The bioabsorbable implants had a slightly better fusion rate (statistically insignificant, p⫽0.14) with equilavent maintenance of sagittal contour and posterior disc height when compared to vertical titanium cages. DISCLOSURES: Device or drug: Hydrosorb (Medtronic Sofamor Danek). Status: Approved for this indication. Device or drug: Infuse (Medtronic Sofamor Danek). Status: Approved for this indication. CONFLICT OF INTEREST: Author (TK) Grant Research Support: Medtronic Sofamor Danek. doi: 10.1016/j.spinee.2004.05.145
P81. Maintenance of sagittal contour following TLIF with an absorbable interbody device Timothy Kuklo1, Michael Rosner1, David Polly, Jr.2; 1Walter Reed Army Medical Center, Washington, DC, USA; 2University of Minnesota, Minneapolis, MN, USA BACKGROUND CONTEXT: Structure interbody support remains a mainstay in the spinal fusion armamentarium in degenerative disc disease, with multiple reports in the literature on various interbody devices. Maintenance of sagittal contour following absorbable devices has not been reported. PURPOSE: The purpose of this study is to evaluate the sagittal contour following single or multi-level interbody fusion to determine the maintenance of sagittal contour and disc height/foraminal height following TLIF for degenerative disc disease.
P26. Scoliosis correction using a new screw with a pivoting reduction post: biomechanical testing and 2 year clinical results Dennis Crandall, MD1, Matthew M. Morrison, BSME2, Douglas Slaughter, MD1, Douglas Baker, BSME2, PJ Hankins, RN, BSN, ONC1; 1 Sonoran Spine Center, Phoenix, AZ, USA; 2Medtronic Sofamor Danek, Memphis, TN, USA BACKGROUND CONTEXT: A new screw with a 180 degree pivoting reduction post was designed to make spinal deformity correction more finely controlled and technically easy. PURPOSE: Biomechanical and clinical studies were performed to evaluate this new Multi-Planar Adjustable (MPA) screw (510K cleared) in correcting scoliosis in adolescents and adults.
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Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S
STUDY DESIGN/SETTING: Biomechanical testing of the new screwrod construct was conducted using a corpectomy model. A Prospective clinical study was conducted with 2 year patient follow up. PATIENT SAMPLE: Clinically, 32 consecutive patients (30 female, 2 male) average 51 years (15–85 years) were surgically treated for scoliosis with posterior instrumented correction and fusion, and prospectively followed 2 years. Anterior release and fusion was required in 26. There were 11 Degenerative, 16 Adult Idiopathic, and 5 Adolescent Idiopathic scoliosis patients. Surgical indications included curve progression, spinal imbalance, or pain failing ⬎6 months conservative care. OUTCOME MEASURES: Outcomes assessed included pre and post-op VAS pain scores, pain medication records, Oswestry scores, and work status. Radiographs were obtained at 2, 3, 6, 9, 12, 18, and 24 months. METHODS: Surgical Technique: Rods were bent into the desired spinal contour. Hooks or screws were used in the thoracic spine. New MPA screws with long threaded reduction posts were used in the lower thoracic and lumbar spine. The reduction posts had the ability to pivot 180 degrees side to side, allowing easy attachment to the rod. Deformity correction was accomplished by: 1) Direct lateral translation of the spine by incremental tightening the reduction nut on the long post of the MPA screws. This precise and finely controlled reduction force was gradually applied over 20–60 minutes. 2) Manual manipulation of the spine by pushing or pulling the long reduction posts attached to the screws in conjunction with rod derotation. 3) Compression or distraction along the rod. All constructs were crosslinked. Spinal cord monitoring was used in all cases. RESULTS: The biomechanical testing of the new screw-rod construct was similar in strength and rigidity to other commonly used multi-axial screwrod constructs. Adult Idiopathic scoliosis averaged 62 degrees (39–90) corrected 72% to 17 degrees (6–40). Degenerative curves averaged 37 degrees (20–75) corrected 71% to 11 degrees (5–21). Adolescent scoliosis averaged 46 degrees corrected 70% to 14 degrees (12–16). Of the 26 patients with pre-op pain, 24 (92%) showed clinical improvement by decreased pain scores (VAS 6.7 pre, 2.4 post), declining medication use, and improved Oswestry scores. All but 2 patients returned to their pre-op work/ student/retired status. There was one wound infection and two nonunions. There were no implant related complications. CONCLUSIONS: Spinal instrumentation currently available achieves scoliosis correction by hook/screw compression or distraction along the rod and by rod derotation. Direct lateral translation of a vertebra is currently only possible using a sublaminar wire or cable. This study presents biomechanical testing and 2 year follow-up on adult and adolescent scoliosis correction using a unique screw with a threaded reduction post that pivots 180 degrees side to side. This feature allows easy rod assembly and fine control of reduction forces in multiple planes to precisely correct scoliosis in a way not previously possible. Improved control and correction of deformity are anticipated using the MPA screw. DISCLOSURES: Device or drug: Multi-planar adjustable (MPA) screw. Status: Approved for this indication. CONFLICT OF INTEREST: Author (DC) Consultant: Consultant for Medtronic Sofamor Danek; Author (DC) Speaker’s Bureau Member: Speaker’s Bureau for Medtronic Sofamor Danek; Author (DC) Other: Unrestricted eductional grant received from Medtronic Sofamor Danek; Authors (MMM, DB) Consultant: Medtronic Sofamor Danek Employee; Authors (MMM, DB) Stockholder: Medtronic Sofamor Danek Stockholder; Author (DB) Speaker’s Bureau Member: Medtronic Sofamor Danek Employee. doi: 10.1016/j.spinee.2004.05.146 P76. Selection of the lowest instrumented vertebra in thoracic adolescent idiopathic scoliosis Lenke type 1 and 2 following segmental posterior spinal fusion Lawrence Lenke1*, Yong-Jung Kim1, Keith Bridwell, MD2, Junghoon Kim, MD3, Samuel Cho4; 1Washington University in St. Louis, Saint Louis, MO, USA; 2Washington University Medical Center, St. Louis, MO, USA; 3MO, USA; 4Washington University Medical Center, MO, USA
BACKGROUND CONTEXT: The safest lowest instrumented vertebra (LIV) in Lenke type 1 (main thoracic) and 2 (double thoracic) adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion is still controversial. PURPOSE: To determine the safest lowest instrumented vertebra (LIV) in Lenke type 1 (main thoracic) and 2 (double thoracic) adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion. STUDY DESIGN/SETTING: A retrospective chart and radiographs review. PATIENT SAMPLE: 194 patients. OUTCOME MEASURES: Radiographs. METHODS: Radiographic and clinical data on 194 consecutive Lenke type 1 and 2 AIS patients (average age; 14.6 years, range 10.1– 20.7 years) with minimum 2-year follow-up (average 5.6 years; 2–16.7 years) treated with instrumented segmental posterior spinal fusion was collected. All patients were grouped according to the preoperative lumbar modifier (A, B, and C) and LIV instrumentation type (Hook vs pedicle screws). Each group was compared with one another in reference to the stable vertebra (SV), neutral vertebra (NV), and lower end vertebra (LEV) of the major curve on the standing AP radiograph. RESULTS: 110 lumbar A modifier patients demonstrated 32⬚ major Cobb angle correction (59⬚⫹11⬚ to 27⬚⫹12⬚). 58 lumbar B modifier and 26 C modifier patients demonstrated 27⬚ and 25⬚ major Cobb angle correction respectively (60⬚⫹12⬚ to 33⬚⫹10⬚ and 60⬚⫹11⬚ to 35⬚⫹12⬚ respectively). The LIV in lumbar A modifier patients were SV-0.87 vertebrae, NV-0.05 vertebrae, and LEV⫹ 1.42 vertebrae. The LIV in lumbar B modifier patients were SV⫹0.22, NV⫹0.81, and LEV⫹ 1.34 vertebrae. The LIV in C modifier patients were SV⫹0.31, NV⫹0.73, and LEV⫹0.96 vertebrae (p⬍0.001 by SV, p⬍0.001 by NV, and p⫽0.220 by LEV). 146–hook instrumentation group demonstrated 27⬚ major Cobb angle correction (59⬚⫹11⬚ to 32⬚⫹11⬚, 46% correction). 48-pedicle screw instrumentation demonstrated 37⬚ major Cobb angle correction (61⬚⫹14⬚ to 24⬚⫹11⬚, 60% correction). The LIV in the hook group were SV-0.29 vertebrae, NV⫹0.45 vertebrae, and LEV⫹ 1.41 vertebrae. The LIV in the pedicle screw group were SV-0.67, NV-0.13, and LEV⫹ 1.11 vertebrae that demonstrating a definite shorter fusion in the screw group with reference to stable and neutral vertebra (p⫽0.022 by SV, p⫽0.006 by NV, and p⫽0.061 by LEV). CONCLUSIONS: The LIV in lumbar A modifier patient was 1 vertebra cephalad than for those lumbar B or C modifier patients with reference to the SV and NV criteria. The LIV in pedicle screw instrumentation was 0.5 vertebrae shorter than for hook instrumentation with reference to the SV and NV criteria. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.147 P71. Effects of adenovirus expressing twelve different bone morphogenetic proteins on proteoglycan metabolism of the intervertebral disc Yejia Zhang, MD, PhD1, Zhen Li, MD1, Tong-Chuan He, MD, PhD2, Howard An, MD1, Shiwen Song, MD PhD1, Eugene Thonar, PhD1, Gunnar Andersson, MD, PhD1, Frank Phillips, MD1; 1Rush University/ Rush- Presbyterian-St. Luke’s Medical Center, Chicago, IL, USA; 2 University of Chicago, Chicago, IL, USA BACKGROUND CONTEXT: The loss of extracellular matrix proteoglycans is a salient feature of intervertebral disc (IVD) degeneration. Certain bone morphogenetic proteins (BMPs) are known to reverse this process in healthy and diseased IVDs; however the direct administration of the protein in vivo will have a relatively short-lived effect. The delivery of BMPs with gene therapy would allow for a sustained protein expression that could promote disc matrix regeneration. To date there have been no studies directly comparing the abilities of different members of the BMP family to promote extracellular matrix production. PURPOSE: Our goal is to compare the relative activities of adenovirus expressing twelve different BMPs on proteoglycan accumulation by adult bovine IVD cells.