5:43 60. Use of recombinant human bone morphogenetic protein-2 as an adjunct in posterolateral lumbar spine fusion CT-scan analysis at one and two years

Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S PURPOSE: To describe surgical techniques and clinical outcomes of the unilateral TLIF with Brantigan I/F cage for degenerative lumbar disorders. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Sixty-one (92.4%) of the first 66 consecutive patients who underwent this type of TLIF were retrospectively reviewed for a minimum 2-year follow-up. The TLIF was conducted in a total of 100 levels: 1-level in 28 patients, 2-level in 27, and 3-level in 6. Mean blood loss and operating time in all patients who underwent 1- to 3-level TLIF was 716 ml and 252 minutes, respectively. OUTCOME MEASURES: Clinical outcomes were evaluated by means of improvement rates of the Japanese Orthopedic Association scoring system (JOA score) as follows: excellent, 85–100%; good, 70–84%; fair, 50–69%; and poor, ⬍50%. Radiographically, disc height, disc angle, axial positioning of the cage which was placed in the opposite side of the portal, and fusion status were evaluated. Axial positioning was graded as follows: excellent, the cage reached to the most contralteral quarter of the disc space; good, placed within the second most contralateral quarter; fair, reached to the second quarter; and poor, did not reach to the second quarter. Fusion status was determined according to Brantigan and Steffee criteria. Statistical analysis was done using paired t test. METHODS: To validate the advantage of this procedure, the abovementioned clinical and radiographic outcomes were discussed. Interbody fusion technique: Aggressive discectomy through a unilateral single portal made more laterally than PLIF was achieved. Following bone grafting to far anterior part of the disc space, the first Brantigan cage was obliquely inserted into the opposite side. Then, the posterior part of the cage was pushed toward the opposite side to be raised up by a cage positioner. After additional bone graft was placed beside the first cage, the second cage was inserted straight ahead through the same portal. Consequently, bilateral anterior column support using the cages with rigid framework design and sufficient bone graft was achieved through the unilateral approach. RESULTS: The mean follow-up period was 30 months (24–37 months). The average improvement rate of the JOA score was 82% (35–100%). Clinical outcome was excellent in 27 patients, good in 21, fair in 11, and poor in 2. Of 100 levels of TLIF, 92 were classified as radiographic fusion. Anterior and posterior disc height was increased from a mean of 25.3% and 16.9% preoperatively to a follow-up mean of 35.6% and 23.2%, respectively (p⬍.001). Disc angle was also increased from a preoperative mean of 4.6 degrees to an average of 7.1 degrees at the follow-up (p⬍.001). The axial positioning of the cage was considered excellent in 12 levels, good in 77, fair in 11, and poor in 0. The following complications were experienced: hardware migration in two patients, deep infection cured by intravenous antibiotics in one. CONCLUSIONS: The unilateral TLIF using two sticks of Brantigan I/F cage per level provided good clinical results without any serious complications. Two Brantigan cages were successfully placed in each level through a single portal in most patients. Although a less invasive unilateral approach was employed, our radiographic outcomes were as good as those in many reported series of the PLIF or TLIF with Brantigan cage via bilateral approach. DISCLOSURES: FDA device/drug: Brantigan I/F cage. Status: Approved for this indication. CONFLICT OF INTEREST: No conflicts.

BACKGROUND CONTEXT: Clinical studies have demonstrated the difficulty in obtaining posterolateral fusions with autogenous bone graft, especially when a CT scan is used for assessment of bone formation. The currently available rhBMP-2 kit includes a dose and carrier optimized for anterior lumbar interbody fusion. It is not known if this kit can be used reliably in the posterolateral spine. PURPOSE: To determine if rhBMP-2 (12 mg @ 1.5mg/mL) delivered on an absorbable collagen sponge (ACS) with an added bulking agent can increase posterolateral lumbar spine fusion success rates and decrease time to fusion with autogenous bone grafts. STUDY DESIGN/SETTING: A prospective clinical cohort study. PATIENT SAMPLE: Thirty-four patients (22 females, 12 males) with an average age of 65.5 years (range 33–84) underwent posterolateral lumbar spine fusions with pedicle screw instrumentation, iliac crest cancellous bone graft, and rhBMP-2 (12 mg) on an absorbable collagen sponge with a bulking agent of autogenous laminectomy bone (n⫽22) or allogeneic demineralized bone matrix (n⫽12). All 34 patients were available for 1-year follow-up and five of them had reached 2 years. OUTCOME MEASURES: CT scans were obtained at 6 months, 1 year, and 2 years postoperatively. METHODS: Axial, coronal, and sagittal computed tomographic reconstructions were blindly evaluated for evidence of osseous fusion on each side at each level. Images were analyzed for evidence of bridging bone and cortication of the fusion mass. Fusion was graded as definitely fused, probably fused, indeterminate, probably not fused, or definitely not fused. An overall score was given to the quality of the fusion mass (fair, good, or excellent). In addition, soft-tissue ossification, intradural ossification, and laminar bone regrowth after decompression were also evaluated. RESULTS: A total of 118 arthrodesis sites were analyzed. 110 levels (94%) were graded as definitely fused, 4 levels probably fused (3%), 2 levels probably not fused (1.5%), and 2 levels definitely not fused (1.5%). Twenty-seven patients (79%) had a fusion mass quality rated as excellent, five (15%) good, and two fair (6%). Only one patient (3%) was identified as having a fair fusion mass bilaterally at the operative level. All patients except one (97%) were found to have at least one side at each level graded as definitely fused. Thirty patients (89%) had attained a mature fusion mass at the 6-month time interval. In four patients (11%) the fusion mass underwent additional maturation and consolidation during the second 6 months (1 year endpoint). None of the five 2-year patients underwent further maturation of their fusion mass. There was no CT evidence of soft-tissue ossification, dural ossification, or laminar bone regrowth in any patient. CONCLUSIONS: Supplementation of iliac crest bone graft with rhBMP2/ACS and a bulking agent resulted in 97% of 118 levels graded as probably or definitely fused in the posterolateral lumbar spine. The fusion masses attained full maturation by the 1-year time interval. This fusion rate appears higher than in other similar populations fused with autogenous iliac crest bone graft alone and assessed by CT scans (50-75%). No rhBMP-2 related adverse effects were noted. DISCLOSURES: FDA device/drug: rhBMP-2 (off-label use). Status: Investigational/not approved. CONFLICT OF INTEREST: Author (SB) Consultant: Medtronic Sofamor Danek. doi: 10.1016/j.spinee.2005.05.062

doi: 10.1016/j.spinee.2005.05.061

5:43 60. Use of recombinant human bone morphogenetic protein-2 as an adjunct in posterolateral lumbar spine fusion CT-scan analysis at one and two years Kern Singh, MD1, Joseph Smucker2, John Rhee, MD3, Scott Boden, MD2; 1Rush University Medical Center, Atlanta, GA, USA; 2Emory University, Atlanta, GA, USA; 3Department of Orthopaedic Surgery, Emory University and Emory Spine Center, Decatur, GA, USA

31S

5:49 61. A prospective multicenter evaluation of a carbon fiber reinforced polymer CFRP cage for one-level anterior lumbar interbody fusion Daniel Kim, MD1, Alexander Vaccaro, MD2, John Thalgott, MD3, John Vender, MD4, John Brantigan, MD5; 1Stanford University, Stanford, CA, USA; 2The Rothman Institute, Philadephia, PA, USA;