title: Histopathologic inflammatory response induced by recombinant bone morphogenetic protein-2 causing radiculopathy after transforaminal lumbar interbody fusion.
abstract: BACKGROUND
  A significant increase in off-label use of recombinant human bone morphogenic protein-2 (rhBMP-2) in posterior lumbar interbody fusion techniques has been seen in the spine community. Numerous reports have demonstrated complications with use of this proinflammatory agent; however, the in vivo response caused by rhBMP-2 has not been characterized on a cellular level.
  
  
  OBJECTIVE
  To report the case of lumbar radiculopathy and the associated histopathologic findings stemming from the inflammatory response to rhBMP-2 used in transforaminal lumbar interbody fusion (TLIF) surgery.
  
  
  METHODS
  Case report.
  
  
  METHODS
  Single patient case report of rhBMP-2 off-label use causing an inflammatory response that resulted in radiculopathy after TLIF surgery.
  
  
  METHODS
  Clinical, radiologic, and histopathologic evidence was used to determine outcomes in this report.
  
  
  METHODS
  A 27-year-old male presented with low back pain and radiculopathy and radiographic evidence of degenerative disc disease and foraminal stenosis. Four weeks after L4-L5 TLIF surgery augmented with rhBMP-2, the patient developed right-sided lower extremity radiculopathy. Magnetic resonance imaging of the lumbar spine demonstrated bilateral fluid collections with the larger right-sided mass compressing the right L4 nerve root.
  
  
  RESULTS
  Surgical decompression of this mass resulted in resolution of his right-sided radicular symptoms. Histologic analysis of the surgical pathology demonstrated diffuse osteoid and woven bone amidst a fibrovascular stroma densely populated by lymphocytes and eosinophils.
  
  
  CONCLUSIONS
  Off-label rhBMP-2 use in posterior interbody fusion techniques can lead to complications. This case serves to identify potential hazards of this growth factor and highlight areas for further study to better understand its in vivo behavior.
authors.affiliation: Department of Orthopedic Surgery and Rehabilitation, University of Wisconsin, Madison, WI 53792, USA.
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Muchow
authors.forename: Wellington K
authors.initials: WK
authors.lastname: Hsu
authors.forename: Paul A
authors.initials: PA
authors.lastname: Anderson
mesh_terms: D000328:Adult; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000009:adverse effects*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000601:surgery; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D056687:Off-Label Use; D011183:Postoperative Complications / Q000139:chemically induced* / Q000473:pathology; D011843:Radiculopathy / Q000139:chemically induced* / Q000473:pathology; D011994:Recombinant Proteins / Q000009:adverse effects*; D013123:Spinal Fusion / Q000379:methods*; D016212:Transforming Growth Factor beta / Q000009:adverse effects*
chemical_list: D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2