title: Influence of the meniscus on friction and degradation of cartilage in the natural knee joint.
abstract: BACKGROUND
  Total meniscectomy has been shown to cause early-onset arthritis in the underlying cartilage and bone in the knee joint, demonstrating that the meniscus plays an important protective role in the load carrying capacity. Relationships between friction and wear in synovial joints are complex due to the biphasic nature of articular cartilage and the time dependency of tribological responses. Determination of friction and wear in the whole natural joint in vitro or in vivo is technically difficult and the tribological effect of meniscectomy has not been previously studied in an articulating knee joint.
  
  
  OBJECTIVE
  The aim of this study was to use a tribological simulation of the medial compartmental bovine knee, to investigate friction and wear, with and without the meniscus. We hypothesised that meniscectomy would lead to elevated contact stress and frictional coefficient across the joint.
  
  
  METHODS
  Skeletally mature bovine medial compartmental knee joints were dissected and mounted in a pendulum friction simulator, which was used to apply physiologically relevant loading and motion. Wear was quantified using micro-MRI scans and surface profilometry.
  
  
  RESULTS
  Knees tested with the intact meniscus showed no change in surface roughness and no detectable cartilage loss or deformation. However, increased contact stress and frictional coefficient upon removal of the meniscus, led to immediate surface fibrillation, biomechanical wear and permanent deformation of cartilage.
  
  
  CONCLUSIONS
  This study presents, for the first time, an in vitro model simulation system to investigate the tribological effects of meniscectomy and meniscus repair and regeneration.
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK. Woodhouse Lane, Leeds LS2 9JT, UK. menlmc@leeds.ac.uk
authors.forename: L
authors.initials: L
authors.lastname: McCann
authors.forename: E
authors.initials: E
authors.lastname: Ingham
authors.forename: Z
authors.initials: Z
authors.lastname: Jin
authors.forename: J
authors.initials: J
authors.lastname: Fisher