P85. Anterior cervical fusion using dense cancellous allografts and dynamic plating

P85. Anterior cervical fusion using dense cancellous allografts and dynamic plating

Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi:...

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Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.233

P85. Anterior cervical fusion using dense cancellous allografts and dynamic plating Daniel Kim1, Hoang Le1, Raju Balabhadra1, Ho-Yeol Zhang2; 1Stanford University, Stanford, CA, USA; 2CA, USA BACKGROUND CONTEXT: Dense cancellous allografts (DCAs), which have become available in recent years, present several distinct biological advantages over cortical or corticocancellous allografts for anterior cervical fusion (ACF). The large surface area available due to trabecular structure of the dense cancellous grafts greatly facilitates early and more complete fusion by early vascularization and cellular penetration. Thus, DCAs tend to integrate with the host bone earlier than cortical or corticocancellous grafts. Clinical efficacy of DCA spacers for ACDF have not been previously reported. PURPOSE: The aim of this study is to evaluate the efficacy of the dense cancellous allografts as a substrate for anterior cervical fusion along with instrumentation. STUDY DESIGN/SETTING: This is a retrospective clinical study PATIENT SAMPLE: Between January 2001 and March 2002, 98 patients underwent anterior cervical discectomy, fusion using dense cancellous allograft bone with instrumentation using dynamic plating. Of these procedures, 60 involved single-level and 38 involved two-level fusions. OUTCOME MEASURES: Clinical symptoms and neurological findings were reviewed from the patient’s charts. Radiographs were evaluated for subsidence and fusion by an experienced spine surgeon who was not involved in the care of these patients. METHODS: Subsidence was assessed at 1, 3, 6, and 12 months and fusion was assessed at 3, 6, and 12 months post-operatively by plain radiographs. Fusion was defined as appearance of bridging trabecular bone and absence of motion in flexion-extension films. RESULTS: The mean follow-up period was 15 (range 12–25) months. Successful fusion was observed in 70%, 84%, and 96% of the cases at 3, 6, and 12 months respectively. The average subsidence for single-level and two fusions were 2.0 mm and 3.2 mm respectively. No allograft or hardware related complications were encountered in our series. CONCLUSIONS: Dense cancellous allografts are very effective as bone graft substitutes for achieving anterior cervical fusion along with instrumentation. Successful fusion was observed in 70% of our cases at 3 months with a fusion rate of 96% at one year. These allografts provide an effective replacement for autologous grafts in cervical interbody fusion. DISCLOSURES: Device or drug: dense cancellous bone. Status: Approved for this indication. CONFLICT OF INTEREST: No Conflicts.

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PATIENT SAMPLE: A series of 182 patients since 1997 having had total lumbar disc replacement with the Charite´ artificial disc, performed by a single surgeon. Of the 182 cases, 5 (2.7%) required surgical revision. OUTCOME MEASURES: Back and leg VAS, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (R-MD), and patient selfassessment of outcome. METHODS: Over the course of 6 years, 182 patients presented with severe discogenic pain with or without sciatica. Failing non-operative treatment they were indicated for total lumbar disc replacement at 1 or 2 levels. A total of 263 Charite´ prostheses were implanted. Five (5) cases of surgical revision were identified. The complications that led to the surgical revision and the techniques employed were documented. Clinical follow-up was documented. RESULTS: Patient #1 had TDR at L3–4 and L4–5 and developed an early anterior subluxation at L3–4. This patient was revised with removal of the original device and received a new Charite´ disc prosthesis. Patient #2 had TDR at L4–5 and L5-S1 and experienced a core dislocation at L5-S1 resulting in a left iliac vein obstruction. This patient had an inferior vena cava umbrella with removal of the prosthesis and conversion to ALIF. Patient #3 had TDR at L4–5 and L5-S1 and experienced increased L5 radicular pain due to over distraction at L5-S1. This patient underwent removal of the prosthesis and conversion to instrumented circumferential fusion. Patient #4 had TDR at L5-S1 and experienced a core dislocation. The prosthesis was removed and a conversion to ALIF was performed. Patient #5 had TDR at L5-S1 and developed a spondylolisthesis secondary to progression of facet arthropathy. The prosthesis remained in situ and was supplemented with an instrumented posterolateral fusion. Mean back VAS was 4.2 (0–7). Mean leg VAS was 2.1 (0–7). Mean ODI was 32.4 (0–58). Mean R-MD was 11.4 (1–18). Patients were asked to rate their satisfaction with their outcome following surgical revision with choices of excellent, good, satisfactory, or poor. In these 5 cases, 4 rated their outcome as excellent and 1 as good. Two patients suffer from the significant comorbidity of rheumatoid arthritis, and 1 is in early postoperative phase. CONCLUSIONS: Considerable scepticism exists regarding the advantages of lumbar disc replacement and significant attention has been given to revision procedures and complications that may arise. 1 A surgical revision rate of 2.7% from a single surgeon’s experience was reported. This rate is well below the rate suggested in the literature with respect to lumbar fusion procedures. 2 Careful patient selection and preoperative planning remain paramount in avoiding the need for revision in the future. As with other types of spinal surgery, a reliable and predictable surgical revision strategy is necessary to manage complications. DISCLOSURES: Device or drug: Charite Artificial Disc. Status: Investigational/Not approved. CONFLICT OF INTEREST: Author (MS) Consultant: Author has a consulting agreement with DePuy Spine; Author (MS) Other: participates as part of DePuy Spine’s product development team. doi: 10.1016/j.spinee.2004.05.235

doi: 10.1016/j.spinee.2004.05.234

P35. Revision strategies for total lumbar disc replacement Matthew Scott-Young, MBBS, FRACS; Pacific Private Clinic, Southport, Queensland, Australia BACKGROUND CONTEXT: Prosthetic devices have been developed to partially or totally replace symptomatic discs. Potential postoperative complications include infection, mechanical failure, loss of fixation, and neurological irritation or deficit. In the event of a complication, a sound surgical salvage strategy can result in a satisfactory outcome for the patient. PURPOSE: To describe the rate of complications requiring surgical revision and the strategy employed in each case resulting in satisfactory patient outcome. STUDY DESIGN/SETTING: Retrospective review of 5 surgical revision cases in patients implanted with the third-generation Charite´ artificial disc prosthesis.

P30. Lumbar microdiscectomy comparing minimally invasive tubular retractors versus standard retractors Arya Nick Shamie, Assistant Professor1, Saman Aboudi2, Larry Khoo1, Jeffrey Wang1; 1University of California, Los Angeles, Santa Monica, CA, USA; 2Chicago Medical School, IL, USA BACKGROUND CONTEXT: Microdiscectomy is typically performed via a small incision utilizing a microscope for enhanced visualization. With the recent interest in minimally invasive surgery, tubular retractors which dilate the muscle fibers have become popular in order to minimize the incision length, while achieving the same surgical goals. The purpose of this study was to compare the results of lumbar microdiscectomy using minimally invasive tubular retractors and standard “open” retractors (standard microdiscectomy vs. MetRx Tube retractors). PURPOSE: To compare the two methods of Microdiscectomy utilizing two different retractors, MetRx tube and the standard (McCullough) retractors.