Question

In order to develop orthopaedic implants that will function for the lifetime of the patient many material and biomechanical design criteria must be considered.   

(a) Explain in brief few of such criteria in design and material selection particularly in joint replacements

(b) What are the possible adverse effects of micromotion and fretting wear between the components of the implant or between the implant and bone?

(c) How would you design an implant to minimize such effects?

Answer 1

(a) Explain in brief few of such criteria in design and material selection particularly in joint replacements

- Elastic --> since it will move throughout the joint

- Non-corrosive --> must not get corroded with H+ or O2 species

- Non reactive --> must not react with any type of body fluid material (oxygen/hydrogne/etc..)

- Brittle material (yet elastic) --> must be strong/sustain tensile strenght

(b) What are the possible adverse effects of micromotion and fretting wear between the components of the implant or between the implant and bone?

The bone and the implant are most likely to have high frictions (fretting). This may cause:

- Increas ein temperature

- Pain directly to bone

- Material wear

- Friction among other parts of the rotation

(c) How would you design an implant to minimize such effects?

- Material most not be abrasive

- Avoid pionty design

- Correct installation/maintennce