title: Does PEEK/HA Enhance Bone Formation Compared With PEEK in a Sheep Cervical Fusion Model?
abstract: BACKGROUND
  Polyetheretherketone (PEEK) has a wide range of clinical applications but does not directly bond to bone. Bulk incorporation of osteoconductive materials including hydroxyapatite (HA) into the PEEK matrix is a potential solution to address the formation of a fibrous tissue layer between PEEK and bone and has not been tested.
  
  
  OBJECTIVE
  Using in vivo ovine animal models, we asked: (1) Does PEEK-HA improve cortical and cancellous bone ongrowth compared with PEEK? (2) Does PEEK-HA improve bone ongrowth and fusion outcome in a more challenging functional ovine cervical fusion model?
  
  
  METHODS
  The in vivo responses of PEEK-HA Enhanced and PEEK-OPTIMA®Natural were evaluated for bone ongrowth in the form of dowels implanted in the cancellous and cortical bone of adult sheep and examined at 4 and 12 weeks as well as interbody cervical fusion at 6, 12, and 26 weeks. The bone-implant interface was evaluated with radiographic and histologic endpoints for a qualitative assessment of direct bone contact of an intervening fibrous tissue later. Gamma-irradiated cortical allograft cages were evaluated as well.
  
  
  RESULTS
  Incorporating HA into the PEEK matrix resulted in more direct bone apposition as opposed to the fibrous tissue interface with PEEK alone in the bone ongrowth as well as interbody cervical fusions. No adverse reactions were found at the implant-bone interface for either material. Radiography and histology revealed resorption and fracture of the allograft devices in vivo.
  
  
  CONCLUSIONS
  Incorporating HA into PEEK provides a more favorable environment than PEEK alone for bone ongrowth. Cervical fusion was improved with PEEK-HA compared with PEEK alone as well as allograft bone interbody devices.
  
  
  CONCLUSIONS
  Improving the bone-implant interface with a PEEK device by incorporating HA may improve interbody fusion results and requires further clinical studies.
authors.affiliation: Surgical & Orthopaedic Research Laboratories, Prince of Wales Clinical School, Prince of Wales Hospital, UNSW Australia, Level 1 Clinical Sciences Building, Randwick, NSW, 2031, Australia. wrwalshau@gmail.com.
authors.forename: William R
authors.initials: WR
authors.lastname: Walsh
authors.affiliation: Surgical & Orthopaedic Research Laboratories, Prince of Wales Clinical School, Prince of Wales Hospital, UNSW Australia, Level 1 Clinical Sciences Building, Randwick, NSW, 2031, Australia.
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Pelletier
authors.affiliation: Surgical & Orthopaedic Research Laboratories, Prince of Wales Clinical School, Prince of Wales Hospital, UNSW Australia, Level 1 Clinical Sciences Building, Randwick, NSW, 2031, Australia.
authors.forename: Nicky
authors.initials: N
authors.lastname: Bertollo
authors.affiliation: Surgical & Orthopaedic Research Laboratories, Prince of Wales Clinical School, Prince of Wales Hospital, UNSW Australia, Level 1 Clinical Sciences Building, Randwick, NSW, 2031, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Christou
authors.affiliation: Surgical & Orthopaedic Research Laboratories, Prince of Wales Clinical School, Prince of Wales Hospital, UNSW Australia, Level 1 Clinical Sciences Building, Randwick, NSW, 2031, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Tan
mesh_terms: D000818:Animals; D001577:Benzophenones; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D017886:Durapatite / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D023421:Models, Animal; D016348:Osseointegration; D010012:Osteogenesis; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers; D019736:Prostheses and Implants; D011474:Prosthesis Design; D012756:Sheep; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D001577:Benzophenones; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D017886:Durapatite