title: A pilot safety and efficacy study of OP-1 putty (rhBMP-7) as an adjunct to iliac crest autograft in posterolateral lumbar fusions.
abstract: The ability of bone morphogenetic proteins (BMPs) to induce bone formation has led to an increasing interest in the potential for their use in fusion surgery. The purpose of this multi-center clinical pilot study was to evaluate the safety of one such BMP-osteogenic protein 1, in the form of OP-1 putty-combined with autograft for intertransverse process fusion of the lumbar spine in patients with symptomatic spinal stenosis and degenerative spondylolisthesis following spinal decompression. Twelve patients with spinal stenosis and degenerative lumbar spondylolisthesis underwent laminectomy and partial or complete medial facetectomy as required for decompression of the neural elements followed by intertransverse process fusion by placing iliac crest autograft and OP-1 putty between the decorticated transverse processes. No instrumentation was used. Patients were followed clinically using the Oswestry scale and radiographically using static and dynamic radiographs to assess their fusion status. Independent and blinded radiologists assessed the films for the presence of bridging bone between the transverse processes and measured translation and angulation on dynamic films using digital calipers. In addition to bridging bone, less than or equal to 5 degrees of angular motion and less than or equal to 2 mm of translation were required to classify the patients as successfully fused, as per the definition of successful fusion provided by the FDA for use in clinical trials involving investigational devices to attain spinal fusion. Radiographic outcome was compared to a historical control (autograft alone fusion without instrumentation for the treatment of degenerative spondylolisthesis). All adverse events were recorded prospectively. The results showed 9 of the 12 patients (75%) obtained at least a 20% improvement in their preoperative Oswestry score, while 6 of 11 patients (55%) with radiographic follow-up achieved a solid fusion by the criteria used in this study. Bridging bone on the anteroposterior film was observed in 10 of the 11 patients (91%). No systemic toxicity, ectopic bone formation, recurrent stenosis or other adverse events related to the OP-1 putty implant were observed. A successful fusion was observed in slightly over half the patients in this study, using stringent criteria without adjunctive spinal instrumentation. This study did not demonstrate the superiority of OP-1 combined with autograft over an autograft alone historical control, in which the fusion rate was approximately 45%. The lack of adverse events related to the OP-1 putty implant in this study is in agreement with other studies supporting the safety of bone morphogenetic proteins in spinal surgery.
authors.affiliation: Department of Orthopaedic Surgery, Thomas Jefferson University, The Rothman Institute, 925 Chestnut St, 5th Floor, Philadelphia, PA 19107, USA. alexvaccaro3@aol.com
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Vaccaro
authors.forename: Tushar
authors.initials: T
authors.lastname: Patel
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Fischgrund
authors.forename: D Greg
authors.initials: DG
authors.lastname: Anderson
authors.forename: Eeric
authors.initials: E
authors.lastname: Truumees
authors.forename: Harry
authors.initials: H
authors.lastname: Herkowitz
authors.forename: Frank
authors.initials: F
authors.lastname: Phillips
authors.forename: Alan
authors.initials: A
authors.lastname: Hilibrand
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Albert
mesh_terms: D000368:Aged; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000009:adverse effects / Q000627:therapeutic use*; D016025:Bone Transplantation / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D007085:Ilium / Q000637:transplantation; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000187:drug effects / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D010865:Pilot Projects; D011183:Postoperative Complications / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control; D011446:Prospective Studies; D011859:Radiography; D016059:Range of Motion, Articular / Q000187:drug effects / Q000502:physiology; D011994:Recombinant Proteins / Q000009:adverse effects / Q000627:therapeutic use; D012086:Reoperation; D012449:Safety; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D013130:Spinal Stenosis / Q000150:complications / Q000188:drug therapy / Q000601:surgery; D013168:Spondylolisthesis / Q000150:complications / Q000188:drug therapy* / Q000601:surgery*; D016212:Transforming Growth Factor beta; D014182:Transplantation, Autologous; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta