title: Regeneration of articular cartilage--evaluation of osteochondral defect repair in the rabbit using multiphasic implants.
abstract: OBJECTIVE
  To investigate whether two different multiphasic implants could initiate and sustain repair of osteochondral defects in rabbits. The implants address the malleable properties of cartilage while also addressing the rigid characteristics of subchondral bone.
  
  
  METHODS
  The bone region of both devices consisted of D, D-L, L-polylactic acid invested with hyaluronan (HY). The cartilage region of the first device was a polyelectrolytic complex (PEC) hydrogel of HY and chitosan. In the second device the cartilage region consisted of type I collagen scaffold. Eighteen rabbits were implanted bilaterally with a device, or underwent defect creation with no implant. At 24 weeks, regenerated tissues were evaluated grossly, histologically and via immunostaining for type II collagen.
  
  
  RESULTS
  PEC devices induced a significantly better repair than untreated shams. Collagen devices resulted in a quality of repair close to that of the PEC group, although its mean repair score (19.0+/-4.2) did not differ significantly from that of the PEC group (20.4+/-3.7) or the shams (16.5+/-6.3). The percentage of hyaline-appearing cartilage in the repair was highest with collagen implants, while the degree of bonding of repair to the host, structural integrity of the neocartilage, and reconstitution of the subchondral bone was greatest with PEC devices. Cartilage in both device-treated sites stained positive for type II collagen and GAG.
  
  
  CONCLUSIONS
  Both implants are capable of maintaining hyaline-appearing tissue at 24 weeks. The physicochemical region between the cartilage and bone compartments makes these devices well suited for delivery of different growth factors or drugs in each compartment, or different doses of the same factor. It also renders these devices excellent vehicles for chondrocyte or stem cell transplantation.
authors.affiliation: Musculoskeletal Research Center, Department of Orthopedic Surgery, New York University-Hospital for Joint Diseases, New York, NY 10003, USA. sallyfrenkel@yahoo.com
authors.forename: S R
authors.initials: SR
authors.lastname: Frenkel
authors.forename: G
authors.initials: G
authors.lastname: Bradica
authors.forename: J H
authors.initials: JH
authors.lastname: Brekke
authors.forename: S M
authors.initials: SM
authors.lastname: Goldman
authors.forename: K
authors.initials: K
authors.lastname: Ieska
authors.forename: P
authors.initials: P
authors.lastname: Issack
authors.forename: M R
authors.initials: MR
authors.lastname: Bong
authors.forename: H
authors.initials: H
authors.lastname: Tian
authors.forename: J
authors.initials: J
authors.lastname: Gokhale
authors.forename: R D
authors.initials: RD
authors.lastname: Coutts
authors.forename: R T
authors.initials: RT
authors.lastname: Kronengold
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000473:pathology*; D003094:Collagen; D005269:Femur / Q000473:pathology*; D048091:Guided Tissue Regeneration; D006820:Hyaluronic Acid; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007719:Knee Joint; D019344:Lactic Acid; D008422:Materials Testing; D023421:Models, Animal; D010007:Osteochondritis / Q000473:pathology / Q000628:therapy*; D011091:Polyesters; D011108:Polymers; D011817:Rabbits; D014945:Wound Healing
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D019344:Lactic Acid; C033616:poly(lactide); D006820:Hyaluronic Acid; D003094:Collagen