Ch 16 - Materials and Closure

Question 1

List some reported used of barbed suture

Answer 1

• Gastropexy
• Gastrotomy
• Enterotomy
• Intestinal anastomosis
• SDFT and gastrocnemius tendon repair

In GIT surgery, results in faster repair with equivalent or better bursting strength and leakage
However, significantly underperforms smooth knotted suture in tendon repair for ultimate tensile strength and gap formation

Question 2

What are the 2 major methods of suture absorption?

Answer 2

• Enzymatic (predominates in natural materials)
• Hydrolytic (Predominates in synthetic sutures)

Question 3

List the disadvantages of Catgut

Answer 3

• Relatively weak
• Not uniform
• High tissue reaction
• Absorption is extremely variable and unpredictable
• very rapid absorption in gastric or intestinal surgery

Question 4

What species of worms produce silk

Answer 4

Bombyx mori
Anaphe pernyi

Question 5

What are the disadvantages of Nylon Leader Line

Answer 5

It was not designed as an implantable biomaterial. It will elongate under constant loads and its physical properties are significantly influenced by steam sterilisation

Steam sterilisation resulted in a 204x increase in elongation

Question 6

What is the strongest form of suture?

Answer 6

Polyester composite sutures eg FiberWire (multifilament UHMW polyethylene core surrounded by braided polyester and polyethylene exterior)

Question 7

What is meant by the warp, weft, and bias of woven mesh

Answer 7

Tend to be more elastic and fluid in the bias direction

Question 8

What is meant by the course and wale of a knitted mesh?

Answer 8

They are anisotropic with more elongation along the course than the wale

Question 9

What is meant by the pore size and porosity of mesh materials? How does this effect its properties?

Answer 9

• The ratio of material to air
• Polypropylene mesh - pore size 0.6-0.9mm with porpsity 28-32%
• ePTFE pore size 20-25nm

Very small pore size will prevent capillary ingrowth causing encapsulation rather than incorporation

Question 10

What biologic materials have been used as mesh?

Answer 10

• Porcine SI submucosa
• Bovine pericardium
• Acellular dermal matrix
• Canine fascia lata

3months after implantation, porcine SIS is histologically non apparent and has been replaced

Fascia lata consistently has shown the best biological properties followed by polypropylene

Question 11

What are the recommendations for implantation of mesh?

Answer 11

• Trimming with electrosurgery may seal edges and prevent fraying
• Create a hem
• Horizontal mattress sutures will engage more mesh
• If under tension, should overlay 1cm of tissue
• Little or no tension, 0.6cm overlap

Question 12

What are the dimensions of regular and wide skin staples? Are skin staples appositional, inverting or everting?

Answer 12

Slightly everting

Question 13

What are the principles of vascular clip application?

Answer 13

• Vessel is skeletonised prior to application
• Diameter of the vessel should be no more than 2/3 and no less than 1/3 the length of the clip
• Clip applied several mm from cut edge
• Arteries and veins clipped seperately

Question 14

What sized staples are in the coloured cartridges of TA devices?

Answer 14

Green - 4.8mm to 2.0mm
Blue - 3.5mm to 1.5mm
White - 2.5mm to 1mm

Question 15

What can linear staplers be used for?

Answer 15

• Pulmonary Sx
• Cardiac Sx
• GI
• hepatobiliary
• reproductive

Question 16

What are the rules regarding tissue thickness for circular stapling devices?

Answer 16

Should not be used when combined tissue thickness is less than 1mm or greater than 2.5mm

Question 17

What are the byproducts of cyanoacrylate glue?

Answer 17

Cyanoacetate and formaldehyde

Question 18

What are the benefits of using cyanoacrylate glue for wound closure?

Answer 18

• Speed
• No need for suture removal
• Reduced cost
• Barrier to microbial penetration
• Antibacterial effects

In people, a study has shown that wounds closed with glue had significantly fewer post-op infections than sutures wounds