Chapter 76 - Metallic Instruments and Implants

Question 1

1. What materials are metallic instruments made from? (4)

Answer 1

• Stainless steel
• Aluminum
• Aluminum alloys
• Titanium and other alloys

Question 2

2. What are the primary features of martensitic steel?

Answer 2

• Highly magnetic and has moderate corrosion resistance
• 400 series stainless steel

Question 3

3. Final hardness of a metal is (directly/inversely) related to the age-hardening temperature

Answer 3

• Inversely

Question 4

4. What are the primary features of austenitic steel?

Answer 4

• Slightly magnetic and excellent corrosion resistance (less edge retention properties than the martensitic)
• 300 series stainless steel

Question 5

5. What are the qualities of aluminum?

Answer 5

• Lightweight
• Low in strength
• Highly ductile
• Nonmagnetic

Question 6

7. How do aluminum alloys compare to pure aluminum instruments?

Answer 6

• They have more strength and are less ductile

Question 7

8. What is galling?

Answer 7

• The adhesive wear (cold welding) that occurs when 2 metals rub together at high points on their mating surfaces

Question 8

6. What are the qualities of aluminum alloys?

Answer 8

• Nonmagnetic
• Lightweight

Question 9

10. Why is it not advisable to mix stainless steel and titanium implants?

Answer 9

• An accelerated form of corrosion, known as galvanic corrosion, can occur

Question 9

9. What are commonly used metallic implant materials for equids? (3)

Answer 9

• Stainless steel
• Unalloyed titanium
• Titanium alloy
• Cobalt alloy

Question 10

11. T/F: Implant quality stainless steel is completely nonmagnetic in all conditions and implants will not exhibit torsional movement or displacement during MRI scans, even in high-field units.

Answer 10

• True

Question 11

13. What is the modulus of elasticity?

Answer 11

• A constant physical property that describes the stress per unit strain in the elastic region

Question 12

15. What is notch sensitivity?

Answer 12

• A term that describes the relative effect that local irregularities or stress raisers have on mechanical properties

Question 12

12. What is electropolishing?

Answer 12

• A surface treatment that consists of applying an electric current to an implant immersed in specially formulated chemical solution under specified conditions of time and voltage

Question 13

14. What is the endurance limit?

Answer 13

• The maximum stress below which a material can presumably endure an infinite number of cycles

Question 14

16. What is the primary method for detecting and identifying device failure modes?

Answer 14

• Fracture surface examination with the scanning electron microscope