title: The use of hyperosmotic saline for chondroprotection: implications for orthopaedic surgery and cartilage repair.
abstract: OBJECTIVE
  Articular cartilage may experience iatrogenic injury during routine orthopaedic/arthroscopic procedures. This could cause chondrocyte death, leading to cartilage degeneration and posttraumatic osteoarthritis. In an in vitro cartilage injury model, chondrocyte death was reduced by increasing the osmolarity of normal saline (NS), the most commonly-used irrigation solution. Here, we studied the effect of hyperosmolar saline (HS) on chondrocyte viability and cartilage repair in an in vivo injury model.
  
  
  METHODS
  Cartilage injury was induced by a single scalpel cut along the patellar groove of 8 week old rats in the absence of irrigation or with either NS (300 mOsm) or HS (600 mOsm). The percentage of cell death (PCD) within the injured area was assessed using confocal microscopy. Repair from injury was evaluated by histology/immunostaining, and inflammatory response by histology, cytokine array analysis and ELISA (enzyme-linked immunosorbent assay).
  
  
  RESULTS
  The PCD in saline-irrigated joints was increased compared to non-irrigated (NI) joints [PCD = 20.8% (95%CI; 14.5, 27.1); PCD = 9.14% (95%CI; 6.3, 11.9); P = 0.0017]. However, hyperosmotic saline reduced chondrocyte death compared to NS (PCD = 10.4% (95%CI; 8.5, 12.3) P = 0.0024). Repair score, type II collagen and aggrecan levels, and injury width, were significantly improved with hyperosmotic compared to NS. Mild synovitis and similar changes in serum cytokine profile occurred in all operated joints irrespective of experimental group.
  
  
  CONCLUSIONS
  Hyperosmotic saline significantly reduced the chondrocyte death associated with scalpel-induced injury and enhanced cartilage repair. This irrigation solution might be useful as a simple chondroprotective strategy and may also reduce unintentional cartilage injury during articular reconstructive surgery and promote integrative cartilage repair, thereby reducing the risk of posttraumatic osteoarthritis.
authors.affiliation: Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, United Kingdom.
authors.forename: N M
authors.initials: NM
authors.lastname: Eltawil
authors.affiliation: MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, United Kingdom.
authors.forename: S E M
authors.initials: SE
authors.lastname: Howie
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Edinburgh, United Kingdom.
authors.forename: A H R W
authors.initials: AH
authors.lastname: Simpson
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Edinburgh, United Kingdom.
authors.forename: A K
authors.initials: AK
authors.lastname: Amin
authors.affiliation: Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, United Kingdom. Electronic address: a.hall@ed.ac.uk.
authors.forename: A C
authors.initials: AC
authors.lastname: Hall
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects* / Q000293:injuries / Q000378:metabolism / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival; D019902:Chondrocytes / Q000187:drug effects* / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D007430:Intraoperative Care; D018613:Microscopy, Confocal; D019637:Orthopedic Procedures; D009994:Osmolar Concentration; D020011:Protective Agents / Q000494:pharmacology*; D051381:Rats; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology; D007507:Therapeutic Irrigation / Q000379:methods
chemical_list: D016207:Cytokines; D020011:Protective Agents; D012462:Saline Solution, Hypertonic; D012965:Sodium Chloride
keywords: Cartilage; Chondrocyte; Chondroprotection; Injury; Osteoarthritis; Repair