title: Replacement of the knee meniscus by a porous polymer implant: a study in dogs.
abstract: BACKGROUND
  Meniscectomy will lead to articular cartilage degeneration in the long term. Therefore, the authors developed an implant to replace the native meniscus.
  
  
  OBJECTIVE
  The porous polymer meniscus implant develops into a neomeniscus and protects the cartilage from degeneration.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  In a dog model, a porous polymer scaffold with optimal properties for tissue infiltration and regeneration of a neomeniscus was implanted and compared with total meniscectomy. The tissue infiltration and redifferentiation in the scaffold, the stiffness of the scaffold, and the articular cartilage degeneration were evaluated.
  
  
  RESULTS
  Three months after implantation, the implant was completely filled with fibrovascular tissue. After 6 months, the central areas of the implant contained cartilage-like tissue with abundant collagen type II and proteoglycans in their matrix. The foreign-body reaction remained limited to a few giant cells in the implant. The compression modulus of the implant-tissue construct still differed significantly from that of the native meniscus, even at 6 months. Cartilage degeneration was observed both in the meniscectomy group and in the implant group.
  
  
  CONCLUSIONS
  The improved properties of these polymer implants resulted in a faster tissue infiltration and in phenotypical differentiation into tissue resembling that of the native meniscus. However, the material characteristics of the implant need to be improved to prevent degeneration of the articular cartilage.
  
  
  CONCLUSIONS
  The porous polymer implant developed into a polymer-tissue construct that resembled the native meniscus, and with improved gliding characteristics, this prosthesis might be a promising implant for the replacement of the meniscus.
authors.affiliation: Orthopaedic Research Laboratory, Department of Orthopaedics, University Medical Center Nijmegen, PO Box 9101, 6500 HB Nijmegen, the Netherlands. t.vantienen@orthop.umcn.nl
authors.forename: Tony G
authors.initials: TG
authors.lastname: Tienen
authors.forename: Ralf G J C
authors.initials: RG
authors.lastname: Heijkants
authors.forename: Jacqueline H
authors.initials: JH
authors.lastname: de Groot
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Pennings
authors.forename: Arend Jan
authors.initials: AJ
authors.lastname: Schouten
authors.forename: Rene P H
authors.initials: RP
authors.lastname: Veth
authors.forename: Pieter
authors.initials: P
authors.lastname: Buma
mesh_terms: D000818:Animals; D004285:Dogs; D005260:Female; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008592:Menisci, Tibial / Q000601:surgery / Q000637:transplantation*; D009426:Netherlands; D011108:Polymers; D016062:Porosity; D019736:Prostheses and Implants
chemical_list: D011108:Polymers