Degradation properties


  • Degradation refers to a chemical process resulting in the cleavage of covalent bonds due to hydrolysis, oxidation or enzymatic processes
  • (Bio)degradation or resorption is chemical breakdown of an implant by a chemical agent (enzyme, cell, organism)
  • Erosion refers to physical changes in size, shape or mass due to degradation, dissolution, ablation or wear
  • Erosion can be distinguished into surface erosion and bulk erosion

Degradation/resorption has an effect on:        

  • Mechanical properties (impactability, strength, stiffnes, Young’s modulus)
  • Biological properties (osteoconduction)
  • Degradability speed
  • Rules of thumb:
    • TCP chemically less stable compared to HA due to high resolution characteristics
    • TCP easily resorbed by osteoclasts compared to HA
    • TCP faster degradation (12-18 months) compared to HA (2-10 years)

In vitro & in vivo dissolution of Ca-P materials depends on:

  • Composition
  • Crystallinity
  • Ca/P ratio
  • Interconnectivity
  • Degradability / type and speed of resorption
  • Mechanical properties
  • Particle size
  • Surface area
  • Production process
  • Patient characteristics: age, gender, health status, co-morbidities


Ca-P bone substitutes have to be intact long enough for bone ongrowth to occur and to maintain stability.