KEY NOTES CHAPTER 1: GENERAL PRINCIPLES (G) Tissue expansion.

Question 1

What is the history of tissue expansion?

Answer 1

Neumann 1957 - air filled sub cut expander for postauricular skin & ear recon (not popular). Radovan 1975 - silicone expander for arm (1976) & breast (1982) Austad 1982 - histological changes

Question 2

What histological changes are seen?

Answer 2

Epidermis thickens (cellular hyperplasia) Dermis thins Muscle thins Adipose tissue atrophies Nerves - altered conductivity

Question 3

Can you define:- Mechanical creep - Biological creep - Stress-relaxation

Answer 3

1. elongation of skin under a constant load over time.- collagen fibres stretch out, become parallel - elastin microfragments - insterstitial fluid is displaced - e.g. stretching skin intrao2. generation of new tissue secondary to persistent chronic stretching.- e.g. pregnancy, tissue expansion. 3. tendency for resistance of skin to a stretching force to decrease when held at a given tension over time - e.g. initially tight when expanded, but not so tight after 1wk.

Question 4

What are the layers of a capsule?

Answer 4

Microscopic appearance (Paysk) 1. Inner Zone → fibrin layer with macrophages 2. Central Zone → elongated fibroblasts and myofibroblasts 3. Transitional Zone → composed of loose collagen fibres 4. Outer Zone → blood vessels and collagen

Question 5

What are the advantages and disadvantages of tissue expansion?

Answer 5

Adv - allows replacement of like with like tissue - best match, colour, texture, hair-bearing quality, sensate Disadv - staged procedure- deformity during expansion- can only do on healed wounds - not good for SSG / radiotherapy skin

Question 6

What are the complications?

Answer 6

• extrusion and wound dehiscence - infection - rupture- migration

Question 7

What is the technique for tissue expansion?

Answer 7

1. place expander remote and radial to scar / defect 2. make the largest pocket possible, and choose expander base to fill pocket 3. place port remote to expander (or integral / self-expanding) 4. usu. capsule is kept after expansion 5. over-expand e.g. in breast for more natural look

Question 8

What is the experience on tissue expansion in limbs?

Answer 8

Overall high risk of complications (infection, migration, port movement - most literature quote 40-50% complication rate)Place above muscle fascia

Question 9

When are tissue expanders contraindicated?

Answer 9

• Open wounds - Immature scar - Irradiation - Under skin graft

Question 10

How are expanders classified?

Answer 10

• Saline filled bags - Shape → oval, rectangle, round, square, crescentric (shorter donor defect as most expansion over central area) - Size → base dimension, projection when inflated - Location of port → Integral or remote, subcut or external - Envelope → smooth or textured, uniform shell or variable thickness to allow preferential expansion in certain directions. May have stiff backing

Question 11

How is expansion performed?

Answer 11

Intraoperative o Sustained traction o Tissue expansion with foley o Sureclosure devices Rapid Expansion - every 2-3 days o Most tissue creep and growth occurs in first 2 days after expansion Conventional Expansion - weekly o tissues to stabilise b/t expansions o Stop when gain sufficient (overexpand slightly)

Question 12

What are the complications of tissue expansion?

Answer 12

Haematoma, infection, exposure, extrusion, pain, neuropraxia, pressure effects.