Cartilage shear dynamics during tibio-femoral articulation: effect of acute joint injury and tribosupplementation on synovial fluid lubrication

Osteoarthritis Cartilage 18(3):8 (2010) PMID 20004636

Objective: To determine the effects of acute injury and tribosupplementation by hyaluronan (HA) on synovial fluid (SF) modulation of cartilage shear during tibio-femoral articulation. Methods: Human osteochondral blocks from the lateral femoral condyle (LFC) and tibial plateau (LTP) were apposed, compressed 13%, and subjected to sliding under video microscopy. Tests were conducted with equine SF from normal joints (NL-SF), SF from acutely injured joints (AI-SF), and AI-SF to which HA was added (AI-SF+HA). Local and overall shear strain (E"x"z) and the lateral displacement (@Dx) at which E"x"z reached 50% of peak values (@Dx"1"/"2) were determined. Results: During articulation, LFC and LTP cartilage E"x"z increased with @Dx and peaked when surfaces slid, with peak E"x"z being maintained during sliding. With AI-SF as lubricant, surface and overall @Dx"1"/"2 were ~40% and ~20% higher, respectively, than values with NL-SF and AI-SF+HA as lubricant. Also, peak E"x"z was markedly higher with AI-SF as lubricant than with NL-SF as lubricant, both near the surface (~80%) and overall (50-200%). Following HA supplementation to AI-SF, E"x"z was reduced from values with AI-SF alone by 30-50% near the surface and 20-30% overall. Magnitudes of surface and overall E"x"z were markedly (~50 to 80%) higher in LTP cartilage than LFC cartilage for all lubricants. Conclusion: Acute injury impairs SF function, elevating cartilage E"x"z markedly during tibio-femoral articulation; such elevated E"x"z may contribute to post-injury associated cartilage degeneration. Since HA partially restores the function of AI-SF, as indicated by E"x"z, tribosupplements may be beneficial in modulating normal cartilage homeostasis.

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