Chapter 78 Local or Subdermal Plexus Flaps Flashcards
In six month old dos, what percentage does skin contribute to total body weight?
12%
What is reported skin thickness in haired skin
0.5 - 5 mm
What is the difference between a simple and a mixed cutaneous artery?
Simple cutaneous artery runs between muscles, with insignificant branching to muscles.
Mixed cutaneous artery runs through muscles, with appreciable muscular branching
What anatomical level do the superficial, middle and deep plexus correlate with?
In dermis:
- Superficial plexus is sub-papillary
- Middle plexus is cutaneous
In hypodermis:
- Deep plexus is subcutaneous
How do subdermal plexus flaps receive their blood supply?
From collateral connections to deep(/subcutaneous) plexus
What percentage of fibre content does collagen account for in skin?
90%
What is meant by ‘delay phenomenon’?
What does Pavletic recommend as ideal schedule for delay of tubed flaps?
Enhanced survival by staged flap development
e.g. incise but dont elevate, partially divide pedicle of an flap (e.g. cut halfway across base), temporarily occlude one pedicle
Pavletic re tubes flaps: Day 18 divide half of base of pedicle (the one thats far from the target wound), day 21 divide other half
What percentage of normal blood flow remains in a single pedicle flap after initial elevation?
And a bipedicle flap?
What does blood flow rise to in delayed flaps after 3 weeks?
10% in single pedicle
40% in bipedicle
120-150% (after re-elevation drops to 90% of normal)
List 5 factors that contribute to the delay phenomenon
- Altered sympathetic tone
- Dilation of choke vessels (link adjacent vascular territories)
- Re-orientation of vessels
- Neovascularisation
- Altered tissue metabolism
- (Possibly ischaemic preconditioning too)
What local treatment has been shown to increase perfusion (n.b. not vascularity) of subdermal plexus flaps
Autologous PRP
List the 7 categories of subdermal plexus flap
- Advancement
- Transposition
- Rotation
- Interpolation
- Plasty
- Distant
- Composite
What are recommendations re length:width ratio of advancement flaps?
Lenght shouldnt exceed twice width.
List a disadvantage of advancement flap
Tension transferred to wound edge. Rotation or transposition better to avoid this
Define an interpolation flap and give an example
Flap had no common edge with defect i.e. have to make bridging inscision or tube
e.g. lip to lid flap
What is the difference between distant direct vs distant indirect flap?
Distant direct is application fo flap to donor site directly i.e. straight away
Distant indirect is by delayed transfer e.g. delayed transfer tubed flap
What three flaps are irotating flaps?
Rotation, transposition and interpolation
List the three types of plasty
In terms of tension, wht does Z and v-Y plasty achieve?
H, Z and V–>Y (and ?M plasty)
Z and V-Y plasty rotate long axis of wound up to 90 degrees transferring tension and reducing elastic recoil
What is a composite flap?
Give an example
Incorporate underlying structures with the skin
e.g.labial advancement, lip to lid, lat dorsi myocutaneous flap
What anatomical structure needs to be incised to allow scrotum to be expanded and used as a flap?
Tunica dartos
What subdermal plexus flap has been reported for reconstruction of prepuce w penile exposure?
BIpedicle subdermal plexus (+ free buccal mucosal flap)
What subdermal plexus flap can be created from the pes?
Phalageal fillet
Breifly outline steps of lip to lid flap
- Make parallel incisions at 45 degrees to line between medial-lateral canthus. incisions directed towards commisure w caudal incision ending just rostral to commisure.
- Incise buccal mucosa in a longitudinal plane (parallel with lip margin) at least 5mm proximal to lip margin.
- Gently dissect flap from buccal and gingival mucosa attachments
- Close oral defect
- Bridging incision from lateral eye wound margin to rostral flap incision
- Suture buccal mucosa to conjuntiva (6/0 - 7/0 multifilament, positioned to avoid abrasion of corneal - contact lens if worried)
- Suture flap skin margins
- Close donor site
List 4 ‘additional’ steps to a distant direct flap, to ensure success
- Test animal tolerance by bandaging limb in poition first
- Leave small hole open for drainage
- Suture rest of limb to trunk in places
- Banage whole area
What are the 4 main complications after subdermal plexus flap?
- Infection
- Seroma
- Dehiscence
- Necrosis
Potential causes for dehiscence: infection, trauma, poor blood supply, flap necrosis or tension (if lack of others then likely tension)
