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
Acellular Dermal Matrix (ADM) for breast reconstruction (Advantages)
- 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
Acellular Dermal Matrix (ADM) for breast reconstruction (Disadvantages)
- Increased seroma rate
- Red breast syndrome: when used with implant or expander (erythema mimicking cellulitis)
Acellular Dermal Matrix (ADM) for Abdominal wall reconstruction (Advantages)
- Provides additional strength in hernia repair
- Helps bridges large abdominal wall defects
- Favored over synthetic materials in contaminated wounds
Acellular Dermal Matrix (ADM) for Chest wall reconstruction (Advantages)
- 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
Acellular Dermal Matrix (ADM) for Head and neck reconstruction (Advantages)
- 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
