title: Extravasation of rhBMP-2 with use of postoperative drains after posterolateral spinal fusion.
abstract: METHODS
  Prospective measurement of rhBMP-2 from drains in a cohort of patients undergoing posterolateral spinal fusion.
  
  
  OBJECTIVE
  To quantify the amount of rhBMP-2 that extravasates into drains after posterolateral fusion using its current commercially available form, rhBMP-2 within an absorbable collagen sponge.
  
  
  BACKGROUND
  Retention of rhBMP-2 at the fusion site is essential for clinical efficacy and avoidance of unintentional bony growth in other areas of the spine. In vitro studies have shown a large degree of rhBMP-2 release from the sponge within the first 48 hours. It is unknown what effect drainage may have on changing the local concentration of BMP at the posterolateral site.
  
  
  METHODS
  The entire contents of drains were collected for 48 hours after surgery from 9 patients who underwent instrumented posterolateral fusion with rhBMP-2. The total amount collected was calculated from the concentration of BMP-2 as measured by enzyme-linked immunosorbent assay.
  
  
  RESULTS
  A median 68 microg of BMP-2 (range, 13-498) was recovered from drains, representing a median 0.58% (range, 0.21%-4.2%) of the amount implanted; adjusted for yield rate, a median 1.08% was recovered. No significant relationships were found between percentage of BMP-2 extravasation and amount implanted, number of levels, blood loss, and drainage output. A mean 54% of the total amount recovered was in the drain within the first 6 hours.
  
  
  CONCLUSIONS
  The greater bleeding and muscular compression associated with posterolateral fusion did not result in a substantial amount of rhBMP-2 extravasation into postoperative drains. Based on the small rates of recovery, suction drains may be placed after even complex surgeries involving large blood loss without the loss of significant amounts of the implanted rhBMP-2 into the drain.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143-0728, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Mok
authors.forename: Salim K
authors.initials: SK
authors.lastname: Durrani
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Piper
authors.forename: Serena S
authors.initials: SS
authors.lastname: Hu
authors.forename: Vedat
authors.initials: V
authors.lastname: Deviren
authors.forename: Sigurd H
authors.initials: SH
authors.lastname: Berven
authors.forename: Shane
authors.initials: S
authors.lastname: Burch
mesh_terms: D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D016022:Case-Control Studies; D004322:Drainage; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D016014:Linear Models; D011446:Prospective Studies; D013123:Spinal Fusion / Q000379:methods*; D018709:Statistics, Nonparametric; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016212:Transforming Growth Factor beta