5:02 23. Long Fusions to L5: Outcomes and Survival

Proceedings of the NASS 21st Annual Meeting / The Spine Journal 6 (2006) 1S–161S PATIENT SAMPLE: 300 patients who received LESI for stenosis with neurogenic claudication were retrospectively studied. OUTCOME MEASURES: All had severe, debilitating symptoms with Oswestry O40 and VAS O6. METHODS: MRIs were reviewed and canal area at the most stenotic level was measured to determine degree of stenosis (mild O1.0 cm2 with trefoil canal; moderate O0.7 cm2 but !1.0 cm2; severe !0.7 cm2). The number of levels with stenosis was documented. Time to failure, measured by need for operative decompression, was calculated. Survival analyses were performed with log-rank test and Cox proportional hazards analysis to determine if differences in failure rates existed between groups with varying degrees of stenosis and number of levels of stenosis. Cost analysis was performed by calculating R, the rate at which surgery must be avoided after LESI for it to be cost-effective: Cepþ (1-R)Csurgery5Csurgery. RESULTS: Hazard calculation demonstrated mean failure time as 0.7 months in patients with severe stenosis; 1.6 months with moderate stenosis at O2 levels; and 38.1 months with mild stenosis. Log-rank test and Cox proportional hazards analyses demonstated significantly higher failure rates in groups with moderate stenosis at multiple levels or severe stenosis when compared with subjects with mild stenosis (p!.02). Cost calculation demonstrated LESI is not cost-effective in patients with severe or moderate multilevel stenosis. CONCLUSIONS: Patients with more involved stenosis are less likely to experience long-term improvement after LESI, and injections are not costeffective in these individuals. The patient and provider should understand the limited long-term success of LESI in these circumstances as a treatment plan is recommended. FDA DEVICE/DRUG STATUS: Not applicable. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/j.spinee.2006.06.039

Wednesday, September 27, 2006 4:56–5:39 PM Concurrent Session 1: Effects of Lumbar Spine Surgery 4:56 22. Thoracic Kyphosis Progression Following Long Lumbar/ Lumbosacral Fusions From the Thoracolumbar Junction to L5-S1 Yongjung Kim, MD1, Keith Bridwell, MD1, Lawrence Lenke, MD1, Seungchul Rhim, MD2, Young-Woo Kim, MD1; 1Washington University in St. Louis, St. Louis, MO, USA; 2Asan Medical Center, South Korea BACKGROUND CONTEXT: There has been no published paper on the postoperative thoracic kyphosis progression after adult lumbar deformity instrumentation and fusion from the thoracolumbar spine to L5-S1. PURPOSE: To determine the postoperative thoracic kyphosis progression after adult lumbar deformity instrumentation and fusion from the thoracolumbar spine to L5-S1. STUDY DESIGN/SETTING: retrospective radiographic study. PATIENT SAMPLE: 80 adult lumbar deformity patients (average age 53.4 years) who underwent long segmental posterior spinal instrumentation and fusion from the thoracolumbar spine to the L5-S1 with a minimum 2-year follow-up. OUTCOME MEASURES: A radiographic assessment. METHODS: A radiographic assessment of 80 adult lumbar deformity patients (average age 53.4 years) who underwent long segmental posterior spinal instrumentation and fusion from the thoracolumbar spine to L5-S1 with a minimum 2-year follow-up (average 4.5 years, 2–15.8 year follow-up) was undertaken. The larger thoracic kyphosis progression was defined as the increase in thoracic kyphosis (T5-T12) at ultimate follow-up compared with the preoperative one of 15 degrees or more (33 of 80 patients).

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RESULTS: The preoperative thoracic sagittal Cobb angle (T5-T12; 24 +17.3 ) progressed to 35 +14.3 at postoperative 8 weeks, and then to 37 +16.3 at ultimate follow-up (average increase 14 +10.8 ). The preoperative lumbar lordosis angle (T12-S1; 33 +19.0 ) increased to 51 +14.6 at postoperative 8 weeks (18 patients with posterior spinal fusion only, 23 patients with osteotomies, and 39 by anterior strut grafts without osteotomy), and then to 47 +16.0 at final follow-up. The larger thoracic kyphosis angle progression (15 or more) between the preoperative and ultimate follow-up related with: larger lumbar lordosis at 8 weeks PO compared with the preoperative thoracic kyphosis 30o or more (vs. !30 , p5.006), all pedicle screw instrumentation (vs. Hybrid, p5.006), larger increase of proximal junctional angle 10 or more at 8 weeks postoperation (vs. !10 , p5.011), and age at surgery O55 years (vs. 20–55 years, p5.033). CONCLUSIONS: One has to anticipate a postoperative increase of thoracic kyphosis (T5-T12) of approximately 14 after long lumbar fusion/instrumentation; the majority of the progression did occur within 8 weeks postoperation. Larger lumbar lordosis at 8 weeks PO compared with the preoperative thoracic kyphosis 30 or more, all pedicle screw instrumentation, larger increase of proximal junctional angle 10 or more at 8 weeks postoperation, and age at surgery O55 years demonstrated significantly larger thoracic kyphosis progression postoperatively. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/j.spinee.2006.06.041

5:02 23. Long Fusions to L5: Outcomes and Survival Ganesh Swamy, MD, FACS1, Erin Boyd2, Sigurd Berven, MD2, Vedat Deviren, MD2, Serena Hu, MD2, David Bradford, MD2; 1University of Calgary, Calgary, Alberta, Canada; 2University of California, San Francisco, San Francisco, CA, USA BACKGROUND CONTEXT: In spinal deformity surgery, the choice of fusion levels at L5-S1 remains a difficult challenge. Long fusions to L5 have demonstrated variable results and may be unreliable, whereas long fusions to the sacrum are associated with more operative time, stages, and complications. The reliability of fusion to L5 has not been well-established. PURPOSE: The purpose of this paper is to report on the outcomes and survival of long fusions to L5 in adult spinal deformity. STUDY DESIGN/SETTING: Retrospective case series. PATIENT SAMPLE: A consecutive series of patients treated with fusions from T11 or higher to L5. 33 patients were identified with fusions from the thoracic spine to L5. 14 patients were excluded, including 7 deaths, 3 patients lost to follow-up, and 4 patients with incomplete radiographic and clinical data sets. 19 patients were examined with complete radiographic and clinical data sets, and more than 5 years follow-up. The indications for long fusion constructs were adult scoliosis in 16, post-irradiation deformity in 1, and post-laminectomy deformity in 2. OUTCOME MEASURES: SRS-30, ODI, SF-12. Radiographic follow-up with 36’’ standing films, complications and need for revision surgery are also reported. METHODS: Clinical and radiographic review. RESULTS: There were 17 females and 2 males, with average age of 50 (range 25–73). 12 patients underwent 1-3 previous operations, while 7 underwent primary procedures. Five underwent posterior only procedures, 14 underwent circumferential fusions. Six of the 19 patients have required extension of the fusion to the pelvis (32%). The average survival of the fusion to L5 in these patients was 35 mos (range 5 mos to 89 mos). Indications for revision included sagittal imbalance and adjacent segment degeneration. Revision operations were generally large in magnitude, with 6550 cc of blood loss and 9.5 hours operative time. An additional 4 patients are

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considering revision operations. Kaplan-Meier survivorship analysis predicted over 60% survival of the index operation at 10 years follow-up. Patients fused to L5 and those revised to S1 had similar scores in SRS, ODI, and SF-12 outcome measures. Some patients reported a change in functional status after revision to sacrum, including change in gait pattern, loss of twisting and bending ability, and more difficulty with perineal care. CONCLUSIONS: Long fusions to L5 in an adult deformity population can yield acceptable results more than 5 years after surgery. Although of smaller magnitude than primary fusions to sacrum, stopping at L5 is associated with a significant revision rate. There may be a functional loss associated with fusion to sacrum. Despite the potential larger morbidity, long thoracolumbar fusions may yield a more predictable result if extended to the sacrum. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. CONFLICT OF INTEREST: No conflicts.

5:14 25. Evaluation of Safety and Efficacy of Pedicle Screw Placement Evaluated By Computed Tomography (CT): 8-Year Review Ronald Lehman, Jr., MD1, Yongjung Kim, MD2, Lawrence Lenke, MD2, Gene Cheh, MD2, Craig Kuhns, MD2, Jacob Buchowski, MD, MS2, Kathryn Keeler2; 1Walter Reed Army Medical Center, Washington, DC, USA; 2Washington University in St. Louis, MO, USA

BACKGROUND CONTEXT: Few studies have reported the results of long adult fusions to L5. The long-term results with respect to subsequent L5-S1 disc degeneration, the need for subsequent revision, and long-term outcomes are unknown. PURPOSE: To present long-term follow-up (minimum 5 years) of adult patients who underwent long thoracolumbar fusions that stop at L5. The intent of the study is to critically evaluate the fate of L5-S1 disc specifically analyzing the amount of subsequent disc degeneration, the need for subsequent revision surgery, and to potentially identify risk factors for subsequent degeneration. STUDY DESIGN/SETTING: A retrospective clinical, radiographic and functional analysis of 30 consecutive patients who had fusions extending from the thoracic spine to L5. PATIENT SAMPLE: 30 consecutive patients treated at a single institution. OUTCOME MEASURES: SRS questionnaire administered preoperatively, postoperatively, and at latest follow-up. METHODS: Patients who had long fusions down to L5 and had a minimum 5-year follow-up were evaluated preoperatively, postoperatively and at latest follow-up with clinical, radiographic, and SRS outcomes measures. RESULTS: 2/30 patients had preoperative advanced degeneration of the L5-S1 disc (Weiner Grade 2). 28/30 patients were assessed as ‘‘healthy discs’’ preoperatively (Weiner Grade 1 or 2). By the latest follow-up, subsequent advanced L5-S1 disc degeneration (SAD) developed in 19 of these 28 patients (68%) who were initially assessed as ‘‘healthy’’ discs. Younger age at the time of surgery is an associated risk factor for developing SAD (p5.04). 6/30 patients (20%) were revised with extension of their fusion to the sacrum at an average of 2.6 years. Inferior SRS pain scores were associated with SAD. CONCLUSIONS: Subsequent advanced L5-S1 DDD developed in 68% of patients after long adult fusions to L5 with minimum 5-year followup and was associated with a significant loss of sagittal alignment. FDA DEVICE/DRUG STATUS: Pedicle Screw: Approved for this indication. CONFLICT OF INTEREST: No conflicts.

BACKGROUND CONTEXT: The in vivo accuracy of free hand pedicle screws placed throughout the deformed spine as evaluated by CT scanning is unknown. We set out to evaluate the change in the accuracy of pedicle screws between 1998–2005. PURPOSE: To evaluate the incremental accuracy of pedicle screws used in the operative treatment of spinal deformity placed via a free hand technique at a single institution over an 8-year period. STUDY DESIGN/SETTING: Retrospective observational study. PATIENT SAMPLE: Adolescents with operative spinal deformity. OUTCOME MEASURES: CT scans, clincial outcomes, neurologic complications, neurophysiologic data. METHODS: A total of 1023 pedicle screws in 60 patients (927 screws for 54 scoliosis patients and 95 screws for 6 kyphosis patients) inserted between T1 and L4 during an 8-year period (164 screws at T1–T4, 321 screws at T5–T8, 347 screws at T9–T12, and 191 screws at L1-L4) were investigated with postoperative CT scans. Patients were divided into 3 groups (Group I51998–2000, Group II52001–2003, and Group III52004– 2005). All pedicle screws were inserted using the free hand technique described by Lenke, with 13 different spinal surgeons placing the screws using anatomic landmarks, specific entry sites, neurophysiologic, and radiographic confirmation. The position of the pedicle screw placement was graded as an acceptable screw versus violated screw with significant violation. This was defined as the axis of the inserted pedicle screw being outside of the outer cortex of the pedicle wall as assessed by CT scans obtained postoperatively. RESULTS: One hundred three among 1023 pedicle screws (9.8%) demonstrated significant mediolateral pedicle wall violations (19 screws with medial wall violation vs. 84 screws with lateral wall violations, p5.001). Factors relating with significantly higher lateral cortical wall violation were screws inserted during the first 2 years and the last 2 years (vs. during the middle 3 years, p!.05) of the study and a kyphotic spine (vs. scoliotic spine, p!.05). Medial violations in the lumbar spine (vs. thoracic spine) were significant (p!.05), as were violations in midthoracic (ie periapical region) vs. the proximal, distal and lumbar spine (p!.05). Right sided pedicle screws (vs. left sided, p5.17) did not demonstrate any significant differences, nor did the change in violations from Group II vs. Group III. Although the number of violations from Group II did not differ significantly from Group III, the number of medial pedicle breeches significantly decreased during that time frame in the thoracic spine (p!.005). Also, the average transverse angle of the acceptable screws was 15.3 and was significantly different from that with either medial (23.0 , p!.001) or lateral (10.6 , p!.001) violation between Group I and Group II. No screws with significant violation demonstrated neurologic, vascular, or visceral complications. CONCLUSIONS: The overall accuracy of acceptable screws by the free hand pedicle screw placement technique performed in a consistent manner under the supervision of the same spine surgeon was 91.2% without any neurologic, vascular, or visceral complications. As deformity surgery progresses and surgeons strive to obtain more fixation points, use larger and longer screws, and obtain more correction power, the free hand technique for pedicle screw placement remains a reliable and safe method for instrumentation. FDA DEVICE/DRUG STATUS: Pedicle Screws: Approved for this indication. CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2006.06.043

doi: 10.1016/j.spinee.2006.06.044

doi: 10.1016/j.spinee.2006.06.042

5:08 24. Thoracolumbar Fusions Stopping at L5: Fate of the L5-S1 Disc With a Minimum 5-Year Follow-Up Craig Kuhns, MD1, Courtney Amor, BS1, Jacob Buchowski, MD, MS1, Ronald Lehman, Jr., MD2, Charles Edwards, MD3, Lawrence Lenke, MD1, Keith Bridwell, MD1; 1Washington University in St. Louis, St. Louis, MO, USA; 2Walter Reed, MD, USA; 3MD, USA