Biomaterials

Question 1

What is the most important clinical aspect of an implanted material? and it’s definition?

Answer 1

• Permanence

- Long term biocompatibility between host and implant

Question 2

Ideal properties for biomaterials

Answer 2

• Biocompatible
• Chemically inert
• Non-allergenic
• Non-carcinogenic
• Sterilizable
• Cost effective
• Easy handling

Question 3

Biologic reactions to a foreign body

Answer 3

• Rejection
• Fibrous encapsulation
• Resorption
• Incorporation

Question 4

Biomaterials Classification

Answer 4

• Autograft
• Allograft
• Xenograft
• Alloplast

Question 5

Biomaterial with most and one with least incorporation

Answer 5

• Most is autograft

- Least is Alloplast

Question 6

Biomaterial with most and one with least resistance to infection

Answer 6

• Most is autograft

- Least is Alloplast

Question 7

Biomaterial with most and one with least Antigenicity

Answer 7

• Most is Xenogeraft

- Least are autograft and alloplast

Question 8

Biomaterial with most and one with least host tissue inflammation reaction

Answer 8

• Most is alloplast

- Least is autograft

Question 9

Biomaterial with most and one with least infectious disease transmission

Answer 9

• Most are allograft and xenograft

- Least are autograft and alloplast

Question 10

Biomaterial with most and one with least availability

Answer 10

• Most is alloplast

- Least is autograft

Question 11

Skin Substitutes (Enumerate)

Answer 11

• Skin Autografts:
  
  • Split-thickness skin graft (STSG)
  • Full thickness skin graft (FTSG)
  • Cultured epidermal autografts (CEA)
• Skin allografts and xenografts
• Acellular dermal matrix (ADM):
  
  • Allogenic ADMs
  • Xenogenic ADMs
  • Acellular bilayered matrix
  • Cellualr dermal matrix
  • Cellular bilayered matrix

Question 12

Stages of STSG Take

Answer 12

• Imbibition (24-48 hours): graft obtains nutrients via capillary action
• Inosculation (48-72 hours): recipient and donor end capillaries align
• Revascularization (4-6 days): full ingrowth of host capillaries into graft

Question 13

Thickness of STSG classification

Answer 13

• Thin: 5/1000 - 12/1000 inch
• Medium: 12/1000 - 16/1000 inch
• Thick: 16/1000 - 30/1000 inch

Question 14

Donor sites for STSG

Answer 14

• Thigh
• Buttock
• Back
• Scalp
• Arm

Question 15

STSG (Advantages)

Answer 15

• High chance of graft survival
• Fast revascularization
• Can reharvest from the same donor site
• Donor site can regenerate hair

Question 16

STSG (Disadvantages)

Answer 16

• High degree of secondary contracture (thinner grafts yield more contracture)
• Poor color and texture match

Question 17

Donor sites for FTSG

Answer 17

• Preauricular and postauricular
• Supraclavicular
• Groin
• Axillary

Question 18

FTSG (Advantages)

Answer 18

• Less secondary contracture
• Better color and texture match
• Improved sensory return

Question 19

FTSG (Disadvantages)

Answer 19

• Lower chance of graft survival
• Slower revascularization
• Must be able to close donor site primarily

Question 20

CEA (Advantages)

Answer 20

Useful in difficult clinical scenarios with limited autologous skin

Question 21

CEA (Disadvantages)

Answer 21

• Expensive
• Time intensive ( 3 weeks for 10000 fold kerationcyte expansion
• Grown with murine fibroblasts and fetal calf serum, thus potentiating possible immunologic reaction and rejection of CEA
• Extremely fragile

Question 22

CEA Example

Answer 22

Epicel (Genzyme) the only FDA approved one

Question 23

Acellular Dermal Matrix (ADM) characteristics

Answer 23

• Non living dermal components from an allogenic or xenogenic donor
• Composed of collagen, elastin, laminin, and glycosaminoglycans
• Incorporate well into host tissue with revascularization initiated 1 to 2 weeks after implantation
• More for reinforcing soft tissue and facilitating wound healing rather than actual skin substitute

Question 24

Acellular Dermal Matrix (ADM) Clinical Applications

Answer 24

• Breast reconstruction
• Abdominal wall reconstruction
• Chest wall reconstruction
• Head and neck reconstruction

Question 25

Acellular Dermal Matrix (ADM) for breast reconstruction (Advantages)

Answer 25

- Provide support and additional coverage in implant or expander-based breast reconstructions - Shown to help increase intra-operative tissue expansion volume and decrease capsular contracture rate

Question 26

Acellular Dermal Matrix (ADM) for breast reconstruction (Disadvantages)

Answer 26

- Increased seroma rate | - Red breast syndrome: when used with implant or expander (erythema mimicking cellulitis)

Question 27

Acellular Dermal Matrix (ADM) for Abdominal wall reconstruction (Advantages)

Answer 27

- Provides additional strength in hernia repair - Helps bridges large abdominal wall defects - Favored over synthetic materials in contaminated wounds

Question 28

Acellular Dermal Matrix (ADM) for Chest wall reconstruction (Advantages)

Answer 28

- Serves as regenerative tissue matrix for chronic wounds - Has been shown to be an effective bridge to definitive STSG coverage in wounds with exposed nerve,vessel, tendon, bone or cartilage

Question 29

Acellular Dermal Matrix (ADM) for Head and neck reconstruction (Advantages)

Answer 29

- Covers intra oral mucosal defects (floor of mouth and tongue - Has been shown to reduce fistula rate in cleft palate repairs - Corrects contour deformities of nose - Eyelid reconstruction - Covers dural defects