P63. Range of motion and adjacent level degeneration after lumbar total disc replacement

Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S OUTCOME MEASURES: Data include demographics, Pre and Post operative clinical parameters including Visual Analog Scale, patient assessment of limitations, improvement, and efficacy. Range of motion was independently measured. Retrograde ejaculation was evaluated for all male patients. Further surgical procedures (including adjacent levels) was tabulated. Complications both intraoperatively and post operatively was noted. METHODS: Direct visualization laparoscopic spinal decompression/foraminotomy and reconstruction utilizing the Acromed-DePuy AETI instrumentation technique was employed. Patients were evaluated in follow-up by 2 seperate physicians and nurse. A tapered carbon fiber cage was utilized along with autogenous iliac bone graft. RESULTS: Retrograde ejaculation-1 (temporary) Bladder dome laceration2 Cage migration-1 (over 200 placed) DVT-1 Ileus-2 Neuorlogic worsening1 Bleeding (over 100 cc)-NONE Infection-NONE Ureteral Injury-NONE Bowel Injury-NONE Visual Analog Scale: Pre-op-8.2 Post-op-3.5 Clinical Improvement: Patient Self Assessment-93% Physician Assessment-88% Would elect to repeat the surgery to obtain the same relief—94% Adjacent level unanticipated surgery at 5 yr. f/u—2% Segmental Lordosis: Pre-op 5 degrees, 8.5 degrees Post-op (70% increase). CONCLUSIONS: Direct visualization laparoscopic decompression/reconstruction is a viable and efficacious procedure. This is the first large scale report of an anterior laparoscopic decompression technique. Furthermore, the reconstruction with significantly improved lordosis and minimal further surgeries at adjacent levels suggests attention to restoring the lordosis may have long term beneficial consequences. DISCLOSURES: Device or drug: carbon fiber cage. Status: Not approved for this indication. CONFLICT OF INTEREST: Author (DM) Consultant: Acromed/ Depuy. doi: 10.1016/j.spinee.2004.05.175

P2. Rate of curve progression in degenerative scoliosis Kingsley R. Chin, MD1, Christopher Furey, MD2, Henry Bohlman, MD3; 1 University of Pennsylvania, Philadelphia, PA, USA; 2Case Western Reserve University, Cleveland, OH, USA; 3Spine Institute, University Hospitals of Cleveland, Cleveland, OH, USA BACKGROUND CONTEXT: Typical symptomatic patients with degenerative scoliosis are elderly with osteoporotic bones. This combination makes it difficult for the treating surgeon to decide when to intervene surgically and whether to fuse the spine after decompression. This scenario often leaves both patient and surgeon with uncertainty as to the risk and rate of curve progression. PURPOSE: The purpose of this study was to assess the rate of curve progression in patients with degenerative lumbar scoliosis treated nonoperatively. STUDY DESIGN/SETTING: Retrospective review of plain radiographs. PATIENT SAMPLE: 15 patients. OUTCOME MEASURES: Curve progression. METHODS: 15 patients, 11 females and one male, with an average age of 68.2 years (range 52 to 80 years) who were followed nonoperatively for degenerative scoliosis were retrospectively reviewed. The Cobb angles of their curves were compared on the day of presentation and at the most recent follow up. The location of the intercrestal line was also noted. RESULTS: The curves averaged 13.1 degrees (range 3 to 22 degrees) at presentation. The range of curve progression was from 0 to 22 degrees over a minimum of 1.2 years to a maximum of 14.4 years. The average curve progressed 1.8 degrees per year (range 0 to 6.7 degrees). Three curves did not progressed over a period of 2, 2.3, and 2.6 years. These curves measured 4, 21, and 22 degrees at presentation. The largest curve progression occurred over a 3.3-year period in a 70 year-old female with an intercrestal line at L4. CONCLUSIONS: Curve progression in degenerative scoliosis is not linear and may progress rapidly. The intercrestal line was not a significant predictor of curve progression in this series.

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DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.176

Thursday, October 28, 2004 9:00–9:30 AM Live Poster Presentations 3 P63. Range of motion and adjacent level degeneration after lumbar total disc replacement Russel Huang, MD1, Federico Girardi2, Moe Lim2, Frank Cammisa, Jr.2, Patrick Tropiano3, Thierry Marnay4; 1Hospital for Special Surgery, Shaker Heights, OH, USA; 2Hospital for Special Surgery, New York, NY, USA; 3Hoˆpital CHU Nord, Marseille, France; 4Castelnau Le Lez, France BACKGROUND CONTEXT: The fundamental theoretical rationale for total disc replacement (TDR) is that preservation of motion may prevent the development of adjacent level degeneration (ALD) seen in long-term followup of fusions. However there are no published data that indicate how much motion is sufficient to reduce the incidence of ALD. Careful analysis of range of motion (ROM) and its relationship to ALD will be a key component of scientific evaluation of the efficacy of TDR relative to the current procedure of choice, fusion. PURPOSE: The purpose of this study is to explore the relationship between ROM and the development of ALD after TDR and to establish thresholds for ROM below which the risk of ALD is increased. STUDY DESIGN/SETTING: Retrospective radiographic review. PATIENT SAMPLE: Forty-two patients with 60 TDRs at 9-year follow-up. OUTCOME MEASURES: Radiographic ROM and ALD. METHODS: We performed a retrospective review of flexion-extension radiographs of 42 patients with 60 Prodisc TDRs at 9-year follow-up. There were 23 males and 19 females. At time of surgery, mean age was 45.2 years (25–65) and mean weight was 72.4 kg (52–102). Twenty-one patients (50%) had prior spine surgery. Twenty-seven patients had TDR at one level, 12 had 2 levels, and 3 had implantation at 3 levels. There was one TDR placed at L2-3, 5 at L3-4, 32 at L4–5, and 22 at L5-S1. Postoperative flexion-extension lateral radiographs were used to determine flexionextension ROM and to evaluate for adjacent level degeneration. Cephalad ´ 2mm adjacent levels were evaluated for ALD: loss of disc space height ¡Y compared to adjacent normal discs, anterior osteophyte formation, or dynamic flexion-extension instability of ⬎3.5 mm (FIG. 1). Graphical analysis

Fig. 1. Example of radiographic adjacent level degeneration (ALD).

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

Fig. 2. Range of motion and prevalence of adjacent level degeneration (ALD). was performed plotting the flexion-extension ROM of the most cephalad TDR (x-axis) against the prevalence of radiographic ALD (y-axis) at 9year follow-up. Statistical significance testing was performed using twotailed Fisher exact test. RESULTS: Of 42 patients evaluated, 10 patients (24%) with radiographic ALD were identified. Four patients had loss of disc space height, 3 had anterior osteophyte formation, and 3 had both height loss and osteophytes. None had static or dynamic listhesis ⬎3.5mm. The mean TDR ROM measured was 3.8⬚ (0–18). Mean ROM was 1.5⬚ at L2-3, 3.8⬚ (0–12) at L3–4, 4.4⬚ (0–18) at L4–5, and 3.1⬚ (0–10) at L5-S1. The patients with ALD had a ROM of 1.6⬚ (0–4) whereas the patients without ALD had ROM 4.7⬚ (0–18), (Student t-test, p⫽0.035). A clear relationship between TDR ROM and the development of ALD at 9-year follow-up was observed. When patients were stratified by ROM, none with ROM 䊐5⬚ developed ALD. The overall prevalence of ALD was 24% but was higher in patients with less ROM (FIG. 2). Patients were divided into those with ROM 䊐5⬚ (n⫽13) and those with motion ⬍5⬚ (n⫽29). The prevalence of ALD was 0% in the high ROM group and 34% in the low ROM group (Fisher exact p⫽0.021, odds ratio 13.5). CONCLUSIONS: These data clearly demonstrate that the prevalence of adjacent level degeneration after TDR is higher in patients with ROM ⬍5⬚, and suggest that 5⬚ of flexion-extension ROM may represent a protective threshold against the development of ALD. This information may prove useful in the design and clinical evaluation of nonfusion technologies in spine surgery. Longer-term follow-up of this and other patient cohorts is essential. DISCLOSURES: Device or drug: PRODISC LUMBAR TOTAL DISC REPLACEMENT. Status: Investigational/Not approved. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.177 P108. Can rhBMP-2 (InFUSE) enhance fusion rates in anterior lumbar interbody fusion using standalone femoral ring allografts? Ben Pradhan, Edgar Dawson, Vikas Patel, Rick Delamarter, Michael Kropf, Hyun Bae; The Spine Institute at St. Johns Health Center, Santa Monica, CA, USA BACKGROUND CONTEXT: Anterior lumbar interbody fusion (ALIF) is a well-accepted procedure, and plays an important role in reconstructive spine surgery. Advances in spinal surgical technology has produced a multitude of anterior interbody implants. Still, the femoral ring allograft (FRA) remains a simple and adequate alternative for anterior structural support in spinal surgery. As a stand-alone device however, like most other impacted allografts, the FRA has fallen into disfavor because of reports of high rates of pseudarthrosis. [1,2] PURPOSE: To determine whether the use of rhBMP-2 (InFUSE) applied to an absorbable collagen sponge (ACS) can enhance fusion rates in ALIF with stand-alone FRAs. We also attempt to analyze the factors that may affect fusion in this surgical setting. STUDY DESIGN/SETTING: This is a retrospective study of 36 consecutive patients who underwent ALIF with stand-alone FRAs. A single surgeon

(ED) at the same institution performed all surgeries using identical technique. Minimum follow-up length was 20 months. PATIENT SAMPLE: All patients included in the study had symptomatic degenerative disc disease diagnosed by symptoms of intractable leg and/ or back pain with positive diagnostic imaging findings. The first 27 consecutive patients received FRAs with autologous bone graft packed inside the intramedullary cavities. In an attempt to increase the fusion rate, the next 9 patients received FRAs in which the intramedullary cavities contained InFUSE-soaked ACS. OUTCOME MEASURES: To determine whether BMP enhanced fusion in these patients, pseudarthrosis rates in the BMP and non-BMP groups were compared. METHODS: Nonunion was diagnosed using flexion/extension radiographs, computed tomography scans, and confirmed during revision surgical procedures. RESULTS: Nonunions were identified in 7 of 27 (26%) patients who underwent stand-alone interbody fusion with FRAs and autologous bone graft. In an effort to improve the fusion rate, the surgeon then switched to adding InFUSE-soaked ACS to the FRAs. However, nonunions were identified in 5 of 9 (56%) of these patients who received BMP, a worse fusion rate than the non-BMP group. (The stand-alone FRA technique was no longer used after it became apparent that the use of BMP was not improving fusion rates.) CONCLUSIONS: ACS with rhBMP-2 was not able to increase the fusion rate in ALIF with stand-alone FRAs. In fact there was a trend toward higher pseudarthrosis rates. These results raise interesting points about the way BMP works, and the environment it needs to function properly. The literature has shown that stand-alone FRAs are susceptible to high nonunion rates, which is likely related to motion since supplemental posterior fixation can increase fusion rates. BMP use in fusion cages and threaded allograft dowels has been shown to be succesful in enhancing fusion. [2– 4] However, in this study, even though the compared groups were similar, BMP did not enhance fusion. The compartment created by the FRA and endplates in which the BMP resides was analyzed in an attempt to rationalize the findings. Important variables were considered to be the blood supply, lack of perforations in the graft, the absence of osteoconductive material within the compartment, and motion beyond that which is amenable for fusion. DISCLOSURES: Device or drug: InFUSE. Status: Investigational/Not approved. Device or drug: Femoral ring allograft. Status: Approved for this indication. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.178 P58. Necromechanical comparison of augmentation techniques for insufficiency fracture Heather McCann, MD, Matthew Lepine, John Glaser; Medical University of South Carolina, Charleston, SC, USA BACKGROUND CONTEXT: Current techniques for insufficiency fracture restore pre-fracture strength and all potentially have the complication of cement extrusion. There is minimal information directly comparing techniques. PURPOSE: To compare three techniques of vertebral body insufficiency fracture augmentation by analyzing restoration of height, strength, and stiffness, and quantifying cement leakage. STUDY DESIGN/SETTING: Ex Vivo mechanical study. PATIENT SAMPLE: Four osteoporotic/osteopenic fresh frozen cadaveric spines (T6–L5). OUTCOME MEASURES: ANOVA for Height, Strength, Stiffness, Measurement of Cement Leakage. METHODS: The vertebral bodies were divided into the three treatment groups and by levels (thoracic, thoraco-lumbar, lumbar). All were compressed via MTS by 25% of their initial height to create compression fractures. The bones were fixed using Vertebroplasty, Osteoplasty (Interpore Cross) or Cavity Creation System (Synthes). Pre and post-treatment height,