P20. Thoracoscopic anterior versus open posterior spinal fusion for adolescent idiopathic scoliosis

Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S after minor screw tip position adjustment according to the lateral x-ray (medial out). RESULTS: Among 15 inaccurate pedicle screws with medial wall violation, 13 screws demonstrated loss of harmonious segmental change in the screw tips and violation of the imaginary midline of the vertebral body (sensitivity 87%). One case demonstrated only loss of harmonious change in the screw tip and the other one case did not demonstrate any significant plain x-ray findings. Among the 50 inaccurate pedicle screws with lateral wall violation, 47 cases demonstrated the loss of harmonious segmental change in the screw tips and no crossing of medial pedicle wall by the pedicle screw inserted (sensitivity 94%). Two cases did not demonstrate any significant plain x-ray findings and the other one case demonstrated only violation of the harmonious segmental change in the screw tips. None of these inarticulate pedicle screws caused any neurologic or vascular complications. CONCLUSIONS: Intraoperative plain radiographs alone were very sensitive to detect inaccurate pedicle screw placement. This stresses the importance of careful intraoperative plain radiographic assessment after pedicle screw insertion to detect malpositioned screws to allow for possible revision during the index operation. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.238

P75. Feasibility of stem cell therapy for intervertebral disc degeneration Satoshi Sobajima1, Adam Shimer2, Joseph Kim2, James Kang2, Lars Gilbertson2; 1Osaka Medical College, Takatsuki, Japan; 2University of Pittsburgh, Pittsburgh, PA, USA BACKGROUND CONTEXT: Recent advances in cellular and molecular biology and tissue engineering have made it possible to contemplate directly treating the intervertebral disc to alter the course of IDD. In particular, stem cells appear to be excellent candidates for cell therapy approaches to IDD because of their ability to renew themselves through cell division and their ability to develop into many different specialized cell types for tissue repair. PURPOSE: The purpose of this study was to test the feasibility of stem cell therapy for intervertebral disc degeneration. STUDY DESIGN/SETTING: In this study, we investigated (1) the invitro response of human mesenchymal stem cells (hMSCs) cocultured with human nucleus pulposus cells (hNPCs), and (2) the in-vivo response of rabbit MSCs transplanted into the rabbit intervertebral disc. PATIENT SAMPLE: (In-vitro study) hNPCs and hMSCs were isolated from patients undergoing spine and hip surgery, respectively. OUTCOME MEASURES: The stem cells were labeled by retrovirusdelivered lacZ reporter genes to enable study of cell survival, localization, and maintenance of transgene expression. METHODS: In-vitro study The hMSCs were co-cultured with hNPCs in a pellet culture at NPC-to-MSC ratios of 100:0, 75:25, 50:50, 25:75, 0:100. Histological analysis was performed by X-gal staining. In-vivo study Rabbit MSCs were isolated from bone marrow aspirate using a differential density technique, and were tagged with retrovirus-delivered lacZ reporter genes for tracking. In the experimental group (n=12 rabbits), L2–3, L3–4, and L4–5 intervertebral discs (IVDs) were each injected with 100,000 lacZ positive MSCs suspended in 15 ul saline. In the control group (n=2 rabbits), the discs were injected with saline alone. Three experimental rabbits each were sacrificed 3, 6, 12, and 24 weeks post-transplantation for histological evaluation of cell viability and localization. RESULTS: In-vitro study Localization of hMSCs within the pellets was dependent upon the NPC-to-MSC ratio. For the 75:25 NPC-to-MSC ratio, the lacZ positive hMSCs were clustered and localized in the center of the pellet, surrounded by hNPCs. For the 25:75 NPC-to-MSC ratio, the pattern was reversed, with hNPCs clustered in the center of the pellet, surrounded by hMSCs. The pattern for the 50:50 NPC-to-MSC ratio appeared to be transitional between these two patterns. In-vivo study LacZ positive hMSCs

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survived in the rabbit IVD up to 24 weeks post-transplantation without apparent decrease in cell number or transgene expression. Localization of hMSCs within the rabbit IVDs was dependent upon the time post-transplantation. The transplanted cells were localized in the NP at 3, 6, and 12 weeks post-transplantation. However, by 24 weeks, the stem cells had apparently migrated to the transition zone and AF—where they exhibited an apparent change in morphology to a more spindle shape similar to native AF cells. CONCLUSIONS: The finding of excellent viability of transplanted stem cells in the harsh environment of the intervertebral disc is a promising first step in the development of stem cell therapy approaches to the treatment of IDD. Moreover, the prolonged lacZ transgene expression suggests the possibility that the transplanted stem cells may serve as a vehicle for delivering therapeutic genes to the disc. Understanding MSCs migration may help in developing strategies to deliver stem cells to annular defects. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.239

P20. Thoracoscopic anterior versus open posterior spinal fusion for adolescent idiopathic scoliosis Baron Lonner1, Dimitry Kondrachov, MD2, Farhan Siddiqi2*, Victor Hayes2, Jeff Silber3; 1New York University, New York, NY, USA; 2North Shore–Long Island Jewish Health System, New Hyde Park, NY, USA; 3 Long Island Jewish Medical Center, Great Neck, NY, USA BACKGROUND CONTEXT: Anterior surgery has been gaining popularity for the treatment of thoracic adolescent idiopathic scoliosis. Despite this, posterior spinal fusion with segmental instrumentation remains the gold standard by which other approaches have been measured. Video-assisted thoracoscopic surgery was recently expanded to encompass anterior spinal instrumentation. Thoracoscopic spinal instrumentation retains the advantages of open anterior surgery while offering the potential for a lesser impact on pulmonary function, less postoperative pain, and improved cosmesis. PURPOSE: The purpose of this study was to compare the results of thoracoscopic spinal fusion with posterior fusion in a consecutive group of patients with thoracic adolescent idiopathic scoliosis. STUDY DESIGN/SETTING: A prospective analysis of consecutive patients treated surgically between January, 1999 and February, 2002 by a single surgeon was performed. PATIENT SAMPLE: 25 patients who underwent posterior segmental spinal instrumentation with a minimum follow-up of 24 months were identified for inclusion in the study. 29 patients who underwent thoracoscopic spinal fusion with instrumentation met the minimum inclusion criteria of 12 months follow-up. OUTCOME MEASURES: Coronal curve correction, lowest instrumented vertebrae, LIV tilt angle correction, coronal balance, and thoracic kyphosis were determined. Operative data assessed included operative time, estimated blood loss, blood transfusions, levels fused, type of bone graft used, and intra-operative and post-operative complications. Pulmonary function was assessed in all patients pre-operatively and at each post-operative visit. All patients were administered the SRS-22 outcome questionnaire preoperatively and at follow-up. METHODS: Surgery was recommended to patients if they had progressive thoracic curvature of 40⬚ or more. All patients meeting criteria were offered either a thoracoscopic anterior spinal instrumentation or posterior spinal fusion. No patients were lost to follow-up in either group. RESULTS: Mean curve correction in the anterior group was from 47.9⬚ to 20⬚ (58.4%) vs. from 48⬚ to 21⬚ (55.5%) in the posterior group; this was not significant. Coronal balance was corrected to within one centimeter and tilt angle of the LIV to under 10 degrees in both groups. Kyphosis was increased in the thoracoscopic group but decreased in the posterior group and was within normal limits for both. In the thoracoscopic group, vital capacity dropped by 24% at 3 weeks post-operatively and increased to 2.9% below baseline at follow-up. In the posterior surgery group, vital

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

capacity initially declined by 12.4% and increased to 1.6% below baseline at follow-up. The follow-up values were not statistically significantly lower at follow-up than prior to surgery for both groups. SRS scores in the thoroscopic group were significantly improved in the overall score (4.0 to 4.4), self image domain (3.8 to 4.5), and patient satisfaction domain (2.8 to 4.6) (p⬍0.05). There were no significant improvements in the posterior spinal fusion group in SRS scores. CONCLUSIONS: Thoracoscopic spinal instrumentation compared favorably to the posterior procedure in the areas of coronal plane curve correction and balance, sagittal contour, operative parameters, complication rate, and pulmonary function. It showed improved results in patient-based outcomes. The procedure offers the advantages of fewer levels fused, more rapid recovery, improved cosmesis, and potentially better long and short term outcome. DISCLOSURES: Device or drug: Eclipse Vertebral body screws/ Medtronic Sofamor Danek/ Stryker- Howmedica) Status: Approved for this indication. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.240

P70. Surgical anatomy for cervical pedicle screw placement Tomomichi Kajino, Hiroshi Taneichi, Kota Suda, Kiyoshi Kaneda; Center for Spinal Disorders and Injuries, Bibai Risai Hospital, Bibai, Hokkaido, Japan BACKGROUND CONTEXT: Cervical pedicle screw placement is technically demanding procedure because cervical pedicles are small in size and this has potential risk to both vertebral artery and neural injury. There have been only few morphological assessments of the cervical pedicles in terms of surgical technique. PURPOSE: The purpose of this study was to determine anatomical relationship between ideal entrance zone and critical points (e.g. lateral and medial pedicle cortex, foramen transversarium) for possible neurovascular injury associated with cervical pedicle screw placement. STUDY DESIGN/SETTING: Distances and angles between an ideal posterior entrance of pedicle screws and critical points for possible neurovascular injury were measured on CAT scan. PATIENT SAMPLE: Total of 240 pedicles from C3 to C7 were measured (48 pedicles for each level). An average age of the subjects was 39.5 years ranging from 17 to 54. Male to female ratio was 2:1. None of the individuals had evidence of infections, neoplasms, or congenital/developmental malformations of the cervical spine. OUTCOME MEASURES: Means and standard deviations for measured distances and angles were calculated separately for male, female, and whole group. METHODS: Distances and angles between an ideal posterior entrance (E) of pedicle screws and following critical points for possible neurovascular injury were measured on CAT scan obtained from 24 normal individuals: (1) medial wall of the cervical pedicles (MW); (2) lateral wall of the cervical pedicles (LW); (3) posterior wall of the foramen transversarium (FT) (Fig. 1). Ideal entrance was defined as an intersection point of surface of the lateral mass and a pedicle axis (PA). Distances between ideal entrance and lateral margin of the lateral mass (L) and center of the lamina (C) were also measured (Fig. 1). RESULTS: An average angle of PA was 45.8 degrees in C3, 49.0 degrees in C4, 46.5 degrees in C5, 43.4 degrees in C6, and 35.0 degrees in C7. The distance E-L was 2.4 mm in C3, 2.5 mm in C4, 2.7 mm in C5, 2.8 mm in C6, and 3.5 mm in C7 on the average. Although the variations in both distance E-LW (14.2–14.6mm) and distance E-MW (13.5–14.0mm) were small in C3 through C6, the former was greater than the latter in each level. The distance E-FT had small variations (11.6–12.4mm) from C3 to C6 as well. The average angles of E-LW and E-MW ranged from 30.7 to 37.5 degrees and from 56.0 to 60.7 degrees, respectively. CONCLUSIONS: The ideal posterior entrance of pedicle screws was approximately 2.5mm medial to lateral margin of the lateral masses and

Fig. 1. correct insertion angle was approximately 45 degrees. Surgeons should confirm whether correct screw hole was made or not when the tip of a pedicle probe or a tap reached to 13–14mm in depth. If inadequate pedicle perforation can be confirmed in this depth, critical neurovascular injury can be securely prevented. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.241

P39. Clinical and radiographic outcomes of lumbar interbody fusion using allograft enriched with bone marrow derived cells prepared by selective stem cell retention Daisuke Togawa*, Isador H. Lieberman, Robert F. Mclain, Bradford J. Richmond, James E. Fleming, Jr., Mary Kay Reinhardt; Cleveland Clinic Foundation, Cleveland, OH, USA BACKGROUND CONTEXT: Spinal fusions represent a large population of bone grafting procedures. There still exists issues of donor site morbidity from iliac crest harvest and a significant non-union rate. Graft materials containing concentrated osteoprogenitor cells have been shown increase bone fusion in animal studies. PURPOSE: The purpose of this study was to describe the early clinical and radiographic results of lumbar interbody fusions using allograft composites enriched with bone marrow-derived cells prepared by selective stem cell retention. STUDY DESIGN/SETTING: Prospective consecutive cohort, Institutional Review Board approved study. PATIENT SAMPLE: Twenty-one patients with symptomatic degenerative disc or degenerative spondylolisthesis scheduled for lumbar interbody fusion were recruited. OUTCOME MEASURES: Clinical outcome data was obtained by Short form-36 Generic Health Questionnaire (SF-36), Oswestry Disability Index (ODI), and Visual Analogue Scale (VAS). Fusion status was radiographically analyzed by plain and flexion/extension X-rays and CT scans by an experienced radiologist. METHODS: Eleven males and twelve females with an average age of 45 (range 20–66) were recruited. The average follow-up period was 19 months (range 6–27). The patients underwent lumbar interbody fusion (ALIF: 12 cases 20 levels, PLIF: 9 cases 10 levels) using allograft enriched with bone marrow-derived cells prepared by selective stem cell retention. During the surgery 55 ccs (range 40.5–90) of bone marrow were aspirated in each patient from bone sites separated by approximately 1 cm by changing the direction and depth of the needle placement. Implantable allograft was enriched with connective tissue progenitor cells using a selective stem cell retention system. Clinical and radiographic outcomes were obtained at 6 weeks, 3, 6 months, 1 and 2 years postoperatively. A total of 30 spinal levels were operated and the fusion status of each level was radiographically evaluated by 4 subcategories (no, possible, probable, and definite) in the plain and flexion/extension X-rays. Radiographic spinal fusion was determined when either “probable” or “definite” was given to the X-ray films