8.9 Two Types of Wear of Articular Cartilage

  • Interfacial
  • Fatigue

  • Interfacial - due to interaction between bearing surfaces
    • Adhesion wear - surface fragments from bearing surfaces in contact with each other adhere and are torn away
    • Abrasion wear - soft material is scraped by hard material (opposing surface or loose particles)
  • Fatigue wear
    • due to accumulation of microscopic damage within the bearing material under repetitive stress; not from surface-to-surface contact
    • Bearing surface failure from repeated application of high loads over short period of time or repetition of low loads over long period of time

  • Effective joint lubrication makes interfacial wear unlikely under normal articular cartilage conditions
  • Interfacial wear may occur in impaired or degenerated synovial joint

8.9.1 Potential Methods for Articular Cartilage Degeneration

  • Magnitude of imposed stresses
  • Total number of sustained stress peaks
  • Change in the collagen-Proteoglycan matrix
  • Change in mechanical properties of the tissue