Chapter 12 Instrumentation

Question 1

What is blade % of lenght of Mayo Scissors?

And Metzenbaum?

Answer 1

Mayo blades 33% of length

Metzenbaum blades 25% of length

Question 2

What is the difference between a chisel and osteotome

Answer 2

Chisel is only beveled on one side

(vs osetotome which is beveled on both sides)

Question 3

What is the benefit of textured tungsten carbide needle holder

Answer 3

• Intermediate needle-holding security
• While minimizing the potential for suture material damage and breakage during know tying

Question 4

What angle should needle holder ratchets be?

Answer 4

39º

(rather than 45º to enhance security of engagement, with clamping moment less than yield moment).

N.B. Should be able to securely clamp needle with box lock closed to second tooth

Question 5

At what ‘tightness’ should needle holder securely grip needle?

Answer 5

Closed to second tooth)

Question 6

How does direction of forceps serrations affect function

Answer 6

Jaw/transverse serrations designed for tip clamping

Longitudinal serrations for jaw-clamping (e.g. OVH pedicle)

Question 7

What is difference between Debakey and Cooley (non-crushing tissue forceps N.B. Not thumb forceps)

Answer 7

Unique pattern of longitudinal ribs

Question 8

How do Crile haemostatic forceps differ from Kelly

Answer 8

Longitudinal serrations of Crile extend 100% of jaws (as do halsted mosquito ones), while Kelly ends about 75% of length

Question 9

List 3 bascic characteristics that microsurgical instruments should have

Answer 9

1. Satin finish to minimise glare
2. Adequate lenght to allow pencil grip
3. Gentle enough closing tension for spring loading

Question 10

How should instrument milk be applied

Answer 10

Manually, not by spraying

Question 11

How long does it take for blood on surface of instrument to start breaking down its surface

Answer 11

10 mins

Question 12

At what tooth should haemostat clamp

Answer 12

1st

(c.f. needle holder which should securely hold needle at second ratchet)

Question 13

Which instruments should not be flash autoclaved and why?

Answer 13

Microsurgical and ophtho because high heat detrimental to fine points

Question 14

In what % of new instruments were flaws identified?

Answer 14

15%

Question 15

List 3 elements that contribute to breakdown of autoclaved instruments

Answer 15

• Tap water
• Metallic ions from residual detergent on surgical wraps
• Moisture

Question 16

What is pitting corrosion

And fretting?

Answer 16

Pitting corrosion is characterized by pinprick-like holes surrounded by discolored spots.

Fretting corrosion manifests as brown discoloration on a friction surface caused by microabrasive destruction of the passive layer.

To avoid:

• Lubricate
• Use demineralized water
• Neutral pH cleaning agents

Question 17

What causes rust?

Answer 17

Rust particles in water/steam or non-corrosion resistant steel

Question 18

What causes yellow-brown/blue-violet disoloroation?

How is it treated

Answer 18

Silicic acid (leakage from water treatment equipment)

Removed by acid-base cleaning with special detergents

Question 19

What type of instrument degradation is blood most liekly to cause?

Answer 19

Pitting corrosion

Question 20

What does corrosion resistance of stainless steel depend on?

Answer 20

Quality and thickness of passive layer

(layer resulting from chemical reaction of chromium and ambient oxygen)

Question 21

Go to chapter (p166) and go through instruments to make sure know the names!

Answer 21

Done?