title: No positive effects of OP-1 device on the incorporation of impacted graft materials after 8 weeks: a bone chamber study in goats.
abstract: BACKGROUND
  Bone morphogenetic proteins (BMPs) have the potential to improve clinical outcome after hip revision surgery by improving graft incorporation and implant fixation. However, impaction of cancellous bone grafts and TCP/HA bone substitute mixed with OP-1 device in a bone chamber in goats in a previous study led to reduced fibrous tissue ingrowth after 4 weeks. New bone formation was not promoted by OP-1. In the current study we examined whether this reduction represented a final loss of ingrowth or was just a delay, and whether the reduction can be overcome and ultimately results in a better late ingrowth.
  
  
  METHODS
  Bone chambers with impacted allografts and impacted TCP/HA granules mixed with 2 doses of OP-1 device were implanted in proximal medial goat tibias. Impacted allografts and TCP/HA not treated with OP-1 served as controls. After 8 weeks, the incorporation was evaluated using histology and histomorphometry.
  
  
  RESULTS
  Histology revealed evidence of bone graft incorporation, which proceeded in a similar way in both allografts and TCP/HA, with and without the addition of OP-1. After 8 weeks, no difference in bone ingrowth was found between the OP-1 groups and their controls. It was only in the allografts that the addition of OP-1 resulted in more fibrous tissue ingrowth.
  
  
  CONCLUSIONS
  We conclude that the previously observed delay in fibrous tissue ingrowth can be only partially overcome.
authors.affiliation: Orthopaedic Research Lab, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
authors.forename: Gerjon
authors.initials: G
authors.lastname: Hannink
authors.forename: B Willem
authors.initials: BW
authors.lastname: Schreurs
authors.forename: Pieter
authors.initials: P
authors.lastname: Buma
mesh_terms: D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage*; D018786:Bone Substitutes / Q000008:administration & dosage; D016025:Bone Transplantation; D006041:Goats; D010012:Osteogenesis / Q000187:drug effects; D011475:Prosthesis Failure; D012086:Reoperation; D014182:Transplantation, Autologous
chemical_list: D019485:Bone Morphogenetic Proteins; D018786:Bone Substitutes