Cartilage boundary lubrication of ovine synovial fluid following anterior cruciate ligament transection: a longitudinal study

Osteoarthritis Cartilage. 2015 Apr;23(4):640-7. doi: 10.1016/j.joca.2014.12.017. Epub 2014 Dec 30.


Objective: To assess ovine synovial fluid (oSF) from different post-injury time points for (1) proteoglycan-4 (PRG4) and hyaluronan (HA) concentration, (2) HA molecular weight (MW) distribution, (3) cartilage boundary lubrication function, and (4) lubricant composition-function relationships. The association between cartilage boundary lubrication and gross cartilage changes after injury was also examined.

Methods: oSF was collected 2, 4, 10, and 20 weeks post anterior cruciate ligament (ACL) transection in five skeletally mature sheep. PRG4 and HA concentrations were measured using sandwich enzyme-linked immunosorbent assay, and HA MW distribution by agarose gel electrophoresis. Cartilage boundary lubrication of oSF was assessed using a cartilage-cartilage friction test. Gross damage to articular cartilage was also quantified at 20 weeks using modified Drez scoring protocol.

Results: Early (2-4 weeks) after ACL injury, PRG4 concentrations were significantly higher (P = 0.045, P = 0.037), and HA concentrations were substantially lower (P = 0.005, P = 0.005) compared to 20 weeks. The HA MW distribution also shifted towards lower ranges in the early post-injury stage. The kinetic friction coefficients were significantly higher 2-4 weeks post injury (P = 0.008 and P = 0.049) compared to 20 weeks. Poor cartilage boundary lubricating ability early after injury was associated with cartilage damage at 20 weeks.

Conclusion: Altered composition and diminished boundary lubrication of oSF early after ACL transection may pre-dispose the articular cartilage to degenerative changes and initiate osteoarthritis (OA). These observations also provide potential motivation for biotherapeutic interventions at earlier time points post injury.

Keywords: ACL injury; Boundary lubrication; Cartilage; Ovine; Synovial fluid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anterior Cruciate Ligament / surgery
  • Anterior Cruciate Ligament Injuries*
  • Cartilage, Articular / physiology*
  • Disease Models, Animal
  • Female
  • Hyaluronic Acid / analysis
  • Hyaluronic Acid / chemistry
  • Longitudinal Studies
  • Molecular Weight
  • Osteoarthritis / etiology
  • Osteoarthritis / physiopathology*
  • Proteoglycans / analysis
  • Sheep
  • Synovial Fluid / chemistry
  • Synovial Fluid / physiology*


  • Proteoglycans
  • Hyaluronic Acid