title: Osteochondral regeneration using a novel aragonite-hyaluronate bi-phasic scaffold in a goat model.
abstract: OBJECTIVE
  The objective of this study was to examine whether different mechanical modifications and/or impregnation of hyaluronic acid (HA) might enhance aragonite-based scaffold properties for the regeneration of cartilage and bone in an animal model.
  
  
  METHODS
  Bi-phasic osteochondral scaffolds were prepared using coralline aragonite with different modifications, including 1- to 2-mm-deep drilled channels in the cartilage phase (Group 1, n = 7) or in the bone phase (Group 2, n = 8), and compared with unmodified coral cylinders (Group 3, n = 8) as well as empty control defects (Group 4, n = 4). In each group, four of the implants were impregnated with HA to the cartilage phase. Osteochondral defects (6 mm diameter, 8 mm depth) were made in medial and lateral femoral condyles of 14 goats, and the scaffolds were implanted according to a randomization chart. After 6 months, cartilage and bone regeneration were evaluated macroscopically and histologically by an external laboratory.
  
  
  RESULTS
  Group 1 implants were replaced by newly formed hyaline cartilage and subchondral bone (combined histological evaluation according to the ICRS II-2010 and O'Driscoll et al. 34 ± 4 n = 7). In this group, the cartilaginous repair tissue showed a smooth contour and was well integrated into the adjacent native cartilage, with morphological evidence of hyaline cartilage as confirmed by the marked presence of proteoglycans, a marked grade of collagen type II and the absence of collagen type I. The average scores in other groups were significantly lower (Group 2 (n = 8) 28.8 ± 11, Group 3 (n = 8) 23 ± 9 and Group 4 (empty control, n = 4) 19.7 ± 15).
  
  
  CONCLUSIONS
  The implants with the mechanical modification and HA impregnation in the cartilage phase outperformed all other types of implant. Although native coral is an excellent material for bone repair, as a stand-alone material implant, it does not regenerate hyaline cartilage. Mechanical modification with drilled channels and impregnation of HA within the coral pores enhanced the scaffold's cartilage regenerative potential. The modified implant shows young hyaline cartilage regeneration. This implant might be useful for the treatment of both chondral and osteochondral defects in humans.
authors.affiliation: III Clinic-Biomechanics Laboratory, Rizzoli Orthopaedic Institute, Via Di Barbiano, 1/10, 40136, Bologna, Italy, e.kon@biomec.ior.it.
authors.forename: E
authors.initials: E
authors.lastname: Kon
authors.forename: G
authors.initials: G
authors.lastname: Filardo
authors.forename: D
authors.initials: D
authors.lastname: Robinson
authors.forename: J A
authors.initials: JA
authors.lastname: Eisman
authors.forename: A
authors.initials: A
authors.lastname: Levy
authors.forename: K
authors.initials: K
authors.lastname: Zaslav
authors.forename: J
authors.initials: J
authors.lastname: Shani
authors.forename: N
authors.initials: N
authors.lastname: Altschuler
mesh_terms: D000818:Animals; D037421:Anthozoa; D001672:Biocompatible Materials; D001842:Bone and Bones / Q000502:physiology*; D002119:Calcium Carbonate; D002356:Cartilage / Q000502:physiology*; D002358:Cartilage, Articular / Q000502:physiology*; D006041:Goats; D006820:Hyaluronic Acid; D023421:Models, Animal; D019736:Prostheses and Implants; D012038:Regeneration / Q000502:physiology*; D054457:Tissue Scaffolds; D014945:Wound Healing
chemical_list: D001672:Biocompatible Materials; D006820:Hyaluronic Acid; D002119:Calcium Carbonate