title: Intra-articular implantation of collagen scaffold carriers is safe in both native and arthrofibrotic rabbit knee joints.
abstract: OBJECTIVE
  Sustained intra-articular delivery of pharmacological agents is an attractive modality but requires use of a safe carrier that would not induce cartilage damage or fibrosis. Collagen scaffolds are widely available and could be used intra-articularly, but no investigation has looked at the safety of collagen scaffolds within synovial joints. The aim of this study was to determine the safety of collagen scaffold implantation in a validatedin vivoanimal model of knee arthrofibrosis.
  
  
  METHODS
  A total of 96 rabbits were randomly and equally assigned to four different groups: arthrotomy alone; arthrotomy and collagen scaffold placement; contracture surgery; and contracture surgery and collagen scaffold placement. Animals were killed in equal numbers at 72 hours, two weeks, eight weeks, and 24 weeks. Joint contracture was measured, and cartilage and synovial samples underwent histological analysis.
  
  
  RESULTS
  Animals that underwent arthrotomy had equivalent joint contractures regardless of scaffold implantation (-13.9°versus-10.9°, equivalence limit 15°). Animals that underwent surgery to induce contracture did not demonstrate equivalent joint contractures with (41.8°) or without (53.9°) collagen scaffold implantation. Chondral damage occurred in similar rates with (11 of 48) and without (nine of 48) scaffold implantation. No significant difference in synovitis was noted between groups. Absorption of the collagen scaffold occurred within eight weeks in all animals CONCLUSION: Our data suggest that intra-articular implantation of a collagen sponge does not induce synovitis or cartilage damage. Implantation in a native joint does not seem to induce contracture. Implantation of the collagen sponge in a rabbit knee model of contracture may decrease the severity of the contracture.Cite this article:J. A. Walker, T. J. Ewald, E. Lewallen, A. Van Wijnen, A. D. Hanssen, B. F. Morrey, M. E. Morrey, M. P. Abdel, J. Sanchez-Sotelo. Intra-articular implantation of collagen scaffold carriers is safe in both native and arthrofibrotic rabbit knee joints.Bone Joint Res2016;6:162-171. DOI: 10.1302/2046-3758.63.BJR-2016-0193.
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Walker
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Ewald
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: E
authors.initials: E
authors.lastname: Lewallen
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: A
authors.initials: A
authors.lastname: Van Wijnen
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Hanssen
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: B F
authors.initials: BF
authors.lastname: Morrey
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Morrey
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Abdel
authors.affiliation: Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA sanchezsotelo.joaquin@mayo.edu.
authors.forename: J
authors.initials: J
authors.lastname: Sanchez-Sotelo
keywords: Arthrofibrosis; Biocompatibility; Biodegradation; Collagen scaffold; Knee joint