4:39 128. Approach Complications in Lumbar Total Disc Replacement

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METHODS: All data were prospectively collected into a comprehensive database. The database was queried to address work status preoperatively and at the latest follow-up point. RESULTS: The minimal follow-up was 14 months. The overall return to work period was determined for those patients receiving an artificial disc and those treated with a fusion. Return to work rates for patients who were not working before surgery were analyzed separately. There was no statistical difference in the demographics or preoperative status between the patients receiving an artificial disc and those treated with a fusion. Patients receiving an arthroplasty had an overall median return to work time of 46 days. The median return to work time for patients receiving an arthrodesis was 61 days (p5.0097). The difference between the two was statistically significant. Patients who were working before surgery returned to work at a median time of 41 and 55 days for the arthroplasty (n5339) and allograft (n5310) groups, respectively (p50.0032). CONCLUSIONS: Patients treated with an artificial cervical disc return to work more rapidly than those treated with an arthrodesis, and the difference between the two is statistically significant. FDA DEVICE/DRUG STATUS: Bryan cervical disc: Investigational/not approved; Prestige cervical disc: Investigational/ Not approved. CONFLICT OF INTEREST: Author (VT) Consultant: Medtronic Sofamor Danek; Author (VT) Royalties: Medtronic Sofamor Danek; Author (PA) Consultant: Medtronic Sofamor Danek; Author (PA) Grant/Research Support: Medtronic Sofamor Danek.

(n53), adjacent segment disease (n51), excessive stress on facet joints (n51). Revision surgeries done were replacement of CA (n51), removal of CA and fusion (n55), posterior re-decompression (n54), insertion of new device at adjacent level (n51). CONCLUSIONS: Complications of CA were seen in 12.4% and revision surgery done in 2.6% of the devices used. Revision strategies involved were replacement of CA, removal of CA and fusion, posterior re-decompression, and insertion of new device at adjacent level. This experience emphasizes the importance of case selection and attention to detail with CA. 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.2006.06.395

Friday, September 29, 2006 4:39–5:39 PM Special Interest Poster Presentation 1: Lumbar Spine Disc Replacement Outcomes

doi: 10.1016/j.spinee.2006.06.161

4:15 127. Revision Strategies for Cervical Arthroplasty: Results of a Multi-Surgeon International Survey Vivek Joseph1, Lali Sekhon, MD, PhD2, Neil Duggal, MD3, Emad Shenouda4, David Choi5, Rudolph Bertagnoli, MD, PhD6, Eric Massicotte, MD, MSc, FRCSC7, Michael Fehlings, MD, PhD, FRCS (C)1; 1Toronto Western Hospital, Toronto, Ontario, Canada; 2 SpineNevada, Reno, NV, USA; 3London Health Sciences Centre, London, Ontario, Canada; 4Frenchay Hospital, Bristol, UK., United Kingdom; 5The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom; 6Klinikum St. Elisabeth, Straubing, Germany BACKGROUND CONTEXT: Conventional treatment for cervical disc disease remains discectomy with fusion, or foraminotomy. Cervical arthroplasty (CA) is becoming increasingly popular, as intuitively, preserving and restoring natural motion to the cervical spine is desirable. Complications and revision strategies of CA, however, have not been focused on. PURPOSE: To look at the incidence and types of complication with cervical arthroplasty (CA) in the hands of various surgeons around the world and how they were dealt with. STUDY DESIGN/SETTING: Questionnaire inquiring about experience of the participating surgeons with CA. PATIENT SAMPLE: A total of 427 implants used in 358 patients were studied. OUTCOME MEASURES: The outcome measures included specific complications after CA, indications for revision surgery, and type of revision surgery done. METHODS: A questionnaire inquiring about specific complications of CA and their revision strategies was sent to the participating surgeons. RESULTS: Seven surgeons completed the questionnaire. The surgeons’ years of experience doing CA varied from 1 to 4 years. The case load of CA done per surgeon averaged 51.1 in a total of 358 patients. A total of 427 implants were used: Prodisc (n5219), Bryan (n5145), Prestige (n561), and PCM (n52). Migration was seen in 5, heterotopic ossification in 4, spontaneous fusion in 4, kyphosis in 31, adjacent segment disease in 3, persistent/new compression in 4, abnormal stress on facet joints in 1, failure at primary surgery 1. Eleven patients had revision surgery: CA extrusion (n52), persistent/new compression (n54), posterior migration

4:39 128. Approach Complications in Lumbar Total Disc Replacement Salvador Brau, MD; University of Southern California, Los Angeles, CA, USA BACKGROUND CONTEXT: With recent approval of two devices for total disc replacement (TDR), the issue of safety in the anterior approach necessary for their implantation becomes an important issue for spine surgeons interested in performing the procedure. PURPOSE: This study was carried out to determine the incidence of approach complications in a large series of patients undergoing lumbar TDR. STUDY DESIGN/SETTING: Data were collected concurrently on patients undergoing lumbar TDR. PATIENT SAMPLE: There were 334 patients operated on from May 2001 to December 2005. All but 16 were part of individual device exemption (IDE) studies for the Food and Drug Administration (FDA) in the U.S. OUTCOME MEASURES: Occurrence of any complications related to the approach were indicative of an unsuccessful outcome. METHODS: All patients undergoing the procedure were followed for evidence of complications that included arterial thrombosis, venous lacerations and thrombosis, retrograde ejaculation, ureteral injury, bowel injury, nerve root injury, infection, and hernia. Any complications found were then tabulated. RESULTS: There were 190 males and 144 females. Of these, 124 had surgery at L5-S1, 45 at L4-5, 105 at L4 to S1, and 19 at L3 to L5. There were 24 three-level cases L3 to S1 and 1 four-level case L2 to S1. One case was at L2-3 and there were 7 hybrid cases, which combined a fusion of one level with a TDR at the adjacent level. Three cases had prior anterior fusions at L4 to S1 and had TDR at the adjacent L3-4 level. One patient had TDRs at L2-3 and L5-S1 skipping L3 to L5. There were 4 left iliac vein lacerations (1.2%) all while working at L4-5 and all with only mild blood loss (200 to 400 cc). In all of these the vein was repaired and the TDR was carried to completion without transfusion or any postoperative sequelae. There was 1 left iliac artery thrombosis; it occurred in a patient with a prior L4 to S1 anterior fusion in whom mobilization of the vessels was quite difficult due to fibrosis from the prior surgery. This event was treated immediately by thrombectomy via a femoral approach after the L3-4 TDR was completed, and there were no postoperative sequelae. There were no arterial injuries in primary cases. There were no instances of retrograde ejaculation in the males, and there were no ureteral injuries or nerve root injuries. Transient ileus occurred in 5 patients but none required naso-

Proceedings of the NASS 21st Annual Meeting / The Spine Journal 6 (2006) 1S–161S gastric decompression. There were no bowel injuries, and no hernias have been reported so far. There were 2 cases of DVT at the calf and one case of ileo-femoral venous thrombosis all presenting approximately a week after surgery. Two of these were treated effectively with anticoagulation, but 1 patient expired due to bleeding from an idiosyncratic reaction to heparin. CONCLUSIONS: This study compares very favorably with published reports of complications for anterior lumbar interbody fusion (ALIF) as well as with the reported approach complication rate in the Charite FDA study, and shows that the approach for lumbar TDR can be performed safely and effectively by experienced access surgeons. The incidence of all venous lacerations at L4-5 continues to demonstrate that this is, by far, the most difficult and more dangerous level to expose. Surgeons with little or no experience in anterior lumbar surgery should attempt lumbar TDR with trepidation, especially at the L4-5 level. 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.2006.06.163

4:45 129. Maverick Total Disc Replacement: A Study of Device Position and Patient Outcomes at Two Years Matthew F. Gornet, MD1, Hallet H. Mathews, MD2, J. Kenneth Burkus, MD3, Kevin A. Rahn, MD4, Jean-Charles Le Huec, MD5, Alan L. Williams, MD6; 1The Orthopedic Center of St. Louis, St. Louis, MO, USA; 2 Mid-Atlantic Spine Specialists, Richmond, VA, USA; 3The Hughston Clinic, Columbus, GA, USA; 4Fort Wayne Orthopaedics, LLC, Fort Wayne, IN, USA; 5Bordeaux, France; 6Blaine, WA, USA BACKGROUND CONTEXT: Total disc arthroplasty for single-level DDD may restore and maintain normal disc height and motion, and may avoid potential adjacent level degeneration. Recent studies suggest that inaccurate device placement may impact patient outcomes. PURPOSE: To examine surgical accuracy and corresponding clinical and radiographic results from four investigators participating in the FDA IDE study of Maverick TDR. STUDY DESIGN/SETTING: A prospective study of consecutively enrolled patients. PATIENT SAMPLE: 33 investigational patients with single-level disc disease (L4-L5 or L5-S1) with no prior surgery at the involved level (prior laminotomy and discectomy were not excluded), and who failed conservative treatment for 6 months. Patients (58% M, 42% F) with a mean age of 37.7 years (range 18–53) included 30.3% seeking workers’ compensation. OUTCOME MEASURES: Device position was graded (Ideal, Satisfactory, Inadequate) in each plane. AP implant position (midsagittal CT cuts) was defined by the distance (mm and %) of the posterior margin of the device from the posterior margin of the inferior vertebrae. Medial-lateral implant position (AP view) was defined by the distance from the midpoint of the device to the midpoint of the end plate. Clinical outcomes were assessed using ODI, SF-36, and back and leg pain questionnaires. Radiographic outcomes were assessed using plain films and CT scans at 24 months postoperatively. METHODS: Digitized patient radiographs were assessed qualitatively by an independent radiologist. Quantitative measures of device position, disc height, center of rotation (COR), angular and translational motion were produced via computer-assisted methods (Medical Metrics, Inc.). Statistical analysis was performed to correlate device position with clinical and radiographic outcomes. RESULTS: Only one patient in each plane was found to have an inadequate device placement at 24 months, despite using no training cases. On average, AP implant position was 3.1 mm from the posterior margin of the vertebral body, an average distance of 10.9% of the end plate length. Lateral implant position was 1.2 mm (2.7%) on average (using absolute measures) from the midline of the end plate. No significant axial angular

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misalignment was noted. There were no significant changes in disc height after the first postoperative visit; no subsidence or migration was observed. Range of motion (ROM) at the index level increased from an average of 9.1  to 12.5  at 24 months, with ROM of 12.5  at the superior adjacent level; values at both levels are within published norms. Global ROM (L1-S1) improved 20  on average, without significant changes in contribution from the index or adjacent levels, suggesting that kinematics were not affected. The average position of the COR was unchanged (p5.51) vs. preoperatively at the index level. No correlation was found between device placement or COR and clinical or radiographic outcomes. At 24 months, mean ODI was 14.4, a 35.2 point improvement (p!.001) vs. preoperatively. The mean SF-36 (PCS) score improved 20.5 points (p!.001) to 48.5, with mean back pain and leg pain scores showing significant (p!.001) improvement at 24 months. CONCLUSIONS: The accurate surgical placement of the Maverick TDR in this cohort of 33 consecutive patientsdwith no training casesdwas coincident with excellent patient clinical and radiographic outcomes. Postoperative rotation is greater than published results for current FDA-approved artificial lumbar discs. Maverick is a promising alternative for patients meeting the strict inclusion criteria for TDR. FDA DEVICE/DRUG STATUS: Maverick Total Disc Replacement: Investigational/not approved. CONFLICT OF INTEREST: Author (MFG) Grant/Research Support: Funded in part by The Spinal Research Foundation (OCSL 2005–02). doi: 10.1016/j.spinee.2006.06.164

4:51 130. Clinical and Radiological Outcomes of Total Disc Replacement in the Patients With Postlaminectomy Syndrome: A Minimum 2 Years Follow-Up Sang-Ho Lee, MD1, Seong-Bae Ban, MD2, Jong Dae Park, MD2, Jin Do Huh, MD3, Eun Jung Lee, MD4, Sang Hyeop Jeon, MD2, Chan Shik Shim, MD2; 1Seoul, South Korea; 2Wooridul Spine Hospital, Seoul, Seoul, South Korea; 3College of Medicine, Kosin University, Seoul, South Korea; 4College of Medicine, Kosin University, South Korea BACKGROUND CONTEXT: Recently, total disc replacement (TDR) of the lumbosacral spine has gained popularity for the treatment of degenerative disc disease as an alternative to spinal fusion. The advantages of TDR include preservation of vertebral motion with decreasing the risk of adjacent segmental degeneration, and maintenance of preoperative spinal sagittal alignment. Although several authors have reported good outcomes of TDR in selected cases, the results of TDR in patients with postlaminectomy syndrome are rare in the literature. PURPOSE: To assess the clinical and radiological outcomes of TDR in postlaminectomy syndrome. STUDY DESIGN/SETTING: A retrospective analysis. PATIENT SAMPLE: Consecutive series of 33 patients (20 males, 13 females; mean age 44.268.1 years) who underwent TDR from February 2002 through October 2003. All the patients had persistent or recurrent back/ leg pain, and had a history of lumbar microdiscectomy before TDR. The operated levels were L4-L5 in 18 patients, L5-S1 in 9 patients, L4-5, L5-S1 in 5 patients, and L3-4, L4-5 in one patient. The mean followup period was 34 months (range, 25 to 45). OUTCOME MEASURES: Clinical and functional outcomes were assessed by using Oswestry Disability Index (ODI), and Visual Analog Scale (VAS). Preoperative and postoperative radiologic change was measured by several parameters including spinal range of motion (ROM), whole lumbar lordotic angle, and degree of disc/facet degeneration. Statistical analysis was performed via paired t test. METHODS: The clinical and radiological results of the 33 patients were evaluated preoperatively and at a minimum 2 years after operation. The postoperative MRI was conducted in 27 patients. Radiological parameters were evaluated by two independent radiologists. The change on alignment