title: Reinforcement of articular cartilage with a tissue-interpenetrating polymer network reduces friction and modulates interstitial fluid load support.
abstract: Osteoarthritis (OA) is associated with increased articular cartilage hydraulic permeability and decreased maintenance of high interstitial fluid load support (IFLS) during articulation, resulting in increased friction on the cartilage solid matrix. This study assesses frictional response following in situ synthesis of an interpenetrating polymer network (IPN) designed to mimic glycosaminoglycans (GAGs) depleted during OA.
  
  
  
  Cylindrical osteochondral explants containing various interpenetrating polymer concentrations were subjected to a torsional friction test under unconfined creep compression. Time-varying coefficient of friction, compressive engineering strain, and normalized strain values (ε/εeq) were calculated and analyzed.
  
  
  
  The polymer network reduced friction coefficient over the duration of the friction test, with statistically significantly reduced friction coefficients (95% confidence interval 14-34% reduced) at equilibrium compressive strain upon completion of the test (P = 0.015). A positive trend was observed relating polymer network concentration with magnitude of friction reduction compared to non-treated tissue.
  
  
  
  The cartilage-interpenetrating polymer treatment improves lubrication by augmenting the biphasic tissue's interstitial fluid phase, and additionally improves the friction dissipation of the tissue's solid matrix. This technique demonstrates potential as a therapy to augment tribological function of articular cartilage.
authors.affiliation: Department of Chemistry, Boston University, Boston, MA, USA; Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. Electronic address: bgcooper@bu.edu.
authors.forename: B G
authors.initials: BG
authors.lastname: Cooper
authors.affiliation: Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; Department of Mechanical Engineering, Boston University, Boston, MA, USA. Electronic address: tlawson@bu.edu.
authors.forename: T B
authors.initials: TB
authors.lastname: Lawson
authors.affiliation: Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; Department of Biomedical Engineering, Boston University, Boston, MA, USA; Department of Medicine, Boston University, Boston, MA, USA; Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA, USA. Electronic address: bsnyder@bidmc.harvard.edu.
authors.forename: B D
authors.initials: BD
authors.lastname: Snyder
authors.affiliation: Department of Chemistry, Boston University, Boston, MA, USA; Department of Biomedical Engineering, Boston University, Boston, MA, USA; Department of Medicine, Boston University, Boston, MA, USA. Electronic address: mgrin@bu.edu.
authors.forename: M W
authors.initials: MW
authors.lastname: Grinstaff
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology; D002358:Cartilage, Articular / Q000502:physiology*; D002417:Cattle; D045604:Extracellular Fluid / Q000502:physiology*; D006025:Glycosaminoglycans / Q000172:deficiency; D008153:Lubrication; D008954:Models, Biological; D010003:Osteoarthritis / Q000503:physiopathology; D010539:Permeability; D011108:Polymers / Q000494:pharmacology*; D013264:Stifle / Q000502:physiology; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D006025:Glycosaminoglycans; D011108:Polymers
keywords: Articular cartilage; Biolubrication; Biomaterials; Friction; Tissue reinforcement