title: Clinical sequelae after rhBMP-2 use in a minimally invasive transforaminal lumbar interbody fusion.
abstract: BACKGROUND
  Recent reports of postoperative radiculitis, bone osteolysis, and symptomatic ectopic bone formation after recombinant human bone morphogenetic protein-2 (rhBMP-2) use in transforaminal lumbar interbody fusions (TLIFs) are a cause for concern.
  
  
  OBJECTIVE
  To determine the clinical and radiographic complications associated with BMP utilization in a minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) environment.
  
  
  METHODS
  Retrospective clinical case series at a single institution.
  
  
  METHODS
  Five hundred seventy-three consecutive patients undergoing an MIS-TLIF.
  
  
  METHODS
  Reoperation rates and total costs associated with complications of rhBMP-2 use and pseudarthrosis.
  
  
  METHODS
  A retrospective review of 610 consecutive patients undergoing an MIS-TLIF (2007-2010) by a single surgeon at our institution was performed (mean age 48.7 years, range 26-82 years). All patients underwent an MIS laminectomy with bilateral facetectomy, single TLIF cage, unilateral pedicle screw fixation, and 12 mg (large kit) or 4.2 mg (small kit) of rhBMP-2. The BMP-2 collagen-soaked sponge was placed anteriorly in the disc space, followed by local bone graft, and then the cage was filled only with local bone and no BMP-2. Patients were evaluated at 6 months and 1 year with computed tomography (CT) scan. Those demonstrating neuroforaminal bone growth, osteolysis/cage migration, or pseudarthrosis were reviewed, and cost data including direct cost/procedure for both index and revision surgeries were collected.
  
  
  RESULTS
  Of the 573 patients, 10 (1.7%) underwent 15 additional procedures based on recalcitrant radiculopathy and CT evidence of neuroforaminal bone growth, vertebral body osteolysis, and/or cage migration. Thirty-nine patients (6.8%) underwent reoperation for clinically symptomatic pseudarthrosis. Bone overgrowth was associated with nerve impingement and radiculopathy in all 10 patients (small kit, n=9; large kit, n=1). Osteolysis and cage migration occurred in 2 (20%) of these same 10 patients. Average total costs were calculated per procedure ($19,224), and the costs for reoperation equaled $14,785 per encounter for neuroforaminal bone growth and $20,267 for pseudarthrosis.
  
  
  CONCLUSIONS
  Symptomatic ectopic bone formation, vertebral osteolysis, and pseudarthrosis are recognized complications with the use of rhBMP-2 in MIS-TLIFs. Potential causes include improper dosage and a closed space that prevents the egress of the postoperative BMP-2 fluid collection. Management of these complications has a substantial cost for the patient and the surgeon and needs to be considered with the off-label use of rhBMP-2.
authors.affiliation: Department of Orthopaedic Surgery, Rush University Medical Center, 1611 W. Harrison St, Suite 400, Chicago, IL, USA. Electronic address: kernsingh@hotmail.com.
authors.forename: Kern
authors.initials: K
authors.lastname: Singh
authors.forename: Sreeharsha V
authors.initials: SV
authors.lastname: Nandyala
authors.forename: Alejandro
authors.initials: A
authors.lastname: Marquez-Lara
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Cha
authors.forename: Safdar N
authors.initials: SN
authors.lastname: Khan
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Fineberg
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Pelton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055396:Bone Morphogenetic Protein 2 / Q000009:adverse effects* / Q000191:economics; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects; D011183:Postoperative Complications / Q000191:economics / Q000453:epidemiology*; D011994:Recombinant Proteins / Q000009:adverse effects / Q000191:economics; D012086:Reoperation / Q000191:economics* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects* / Q000191:economics / Q000379:methods*; D016212:Transforming Growth Factor beta / Q000009:adverse effects* / Q000191:economics
chemical_list: D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2
keywords: Bone growth; MIS-TLIF; Neuroforaminal; Pseudarthrosis; rhBMP-2