title: Surface fissures in articular cartilage: new concepts, hypotheses and modeling.
abstract: OBJECTIVE
  Clarification and mesomechanical modeling of the inception of fissures at the surface of articular cartilage.
  
  
  METHODS
  Articular cartilage is described as a macroscopically heterogeneous medium consisting of zones - layers - with different orientation of collagen fibers.
  
  
  BACKGROUND
  Degradation of mechanical properties of cartilage is a serious, still not fully clarified problem that deserves attention.
  
  
  METHODS
  Theoretical analysis based on a survey of known experimental findings related to the subject. The general author's mesomechanical concept of modeling heterogeneous media is applied to the elucidation and description of the formation of fissures at the surface of articular cartilage.
  
  
  RESULTS
  Our model clarifies how the high tensile stresses in the collagen fibers of the superficial tangential zone depend on the rate of loading.
  
  
  CONCLUSIONS
  The superficial cracks are caused predominantly by a very quick loading. This explains among others the high incidence of post-traumatic osteoarthritis of the lower extremity after accidents and injuries in sports.
  
  
  CONCLUSIONS
  Superficial fissures in articular cartilage are observed in joints with primary osteoarthritis. The current study specifies the kinds of loading that lead to their inception.
authors.affiliation: Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prosecká 76, 190 00 Prague 9, Czech Republic. kafka@itam.cs.cz
authors.forename: Vratislav
authors.initials: V
authors.lastname: Kafka
mesh_terms: D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000293:injuries* / Q000502:physiology*; D019245:Compressive Strength; D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D010003:Osteoarthritis / Q000503:physiopathology; D013314:Stress, Mechanical; D013718:Tensile Strength