Biomaterials Flashcards
What is the most important clinical aspect of an implanted material? and it’s definition?
- Permanence
- Long term biocompatibility between host and implant
Ideal properties for biomaterials
- Biocompatible
- Chemically inert
- Non-allergenic
- Non-carcinogenic
- Sterilizable
- Cost effective
- Easy handling
Biologic reactions to a foreign body
- Rejection
- Fibrous encapsulation
- Resorption
- Incorporation
Biomaterials Classification
- Autograft
- Allograft
- Xenograft
- Alloplast
Biomaterial with most and one with least incorporation
- Most is autograft
- Least is Alloplast
Biomaterial with most and one with least resistance to infection
- Most is autograft
- Least is Alloplast
Biomaterial with most and one with least Antigenicity
- Most is Xenogeraft
- Least are autograft and alloplast
Biomaterial with most and one with least host tissue inflammation reaction
- Most is alloplast
- Least is autograft
Biomaterial with most and one with least infectious disease transmission
- Most are allograft and xenograft
- Least are autograft and alloplast
Biomaterial with most and one with least availability
- Most is alloplast
- Least is autograft
Skin Substitutes (Enumerate)
- 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
Stages of STSG Take
- 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
Thickness of STSG classification
- Thin: 5/1000 - 12/1000 inch
- Medium: 12/1000 - 16/1000 inch
- Thick: 16/1000 - 30/1000 inch
Donor sites for STSG
- Thigh
- Buttock
- Back
- Scalp
- Arm
STSG (Advantages)
- High chance of graft survival
- Fast revascularization
- Can reharvest from the same donor site
- Donor site can regenerate hair
STSG (Disadvantages)
- High degree of secondary contracture (thinner grafts yield more contracture)
- Poor color and texture match
Donor sites for FTSG
- Preauricular and postauricular
- Supraclavicular
- Groin
- Axillary
FTSG (Advantages)
- Less secondary contracture
- Better color and texture match
- Improved sensory return
FTSG (Disadvantages)
- Lower chance of graft survival
- Slower revascularization
- Must be able to close donor site primarily
CEA (Advantages)
Useful in difficult clinical scenarios with limited autologous skin
CEA (Disadvantages)
- 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
CEA Example
Epicel (Genzyme) the only FDA approved one
Acellular Dermal Matrix (ADM) characteristics
- 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
Acellular Dermal Matrix (ADM) Clinical Applications
- Breast reconstruction
- Abdominal wall reconstruction
- Chest wall reconstruction
- Head and neck reconstruction
