- Skin is composed of four basic layers:
- Papillary dermis
- reticular dermis
- Primary blood supply to the skin:
–deep vascular plexus (sub dermal):
- between the reticular dermis and subcutaneous fat
–superficial vascular plexus (dermal):
- runs through the superficial dermal papillae of the papillary dermis.
- epidermis: supplied by the superficial plexus via diffusion
- vessels of the dermal and sub dermal plexus travel parallel to the skin and are supplied by:
–travel between muscles within fascial septae
–most abundant among the long and thin muscles of the extremities
–pass perpendicularly through muscles
–most common within the broad and flat muscles of the torso
- Three-dimensional composite of skin, soft tissue and bone supplied by a single source artery
- Reduced-caliber choke vessels provide communication and modify blood flow between neighboringangiosomes.
- single source vessel may supply multipleangiosomes.
- Knowledge of source vessel location andangiosomeboundaries may help increase flap viability by designing known angiosome’s within the boundaries of a flap.
- A flap may be classified based on its blood supply as:
- no single dominant vessel
- primarily supplied by the dermal and sub dermal vascular plexuses
- axial flaps are supplied by a named artery and vein
- allows for a longer flap design with a narrow pedicle
- axial flap design
- source vessel is dividedproximallyàblood supply is dependent on retrograde flow through the distal artery
–possess all layers of the epidermis and dermis as well as the superficial fascia
–contain all layers of the epidermis, dermis, subcutaneous, deep fascia
–more robust vascular supply
–utilized in larger defects requiring intermediate bulk
–may be designed as local, regional or free flaps that can be sensate
- Musculocutaneous vs. Muscle
–Musculocutaneous flaps possess all the same layers as a fasciocutaneous flaps
–greater arc of rotation, increased bulk, classically thought to have improved function and more resistance to infection
–Used commonly for:
- reconstruction of breasts
- irradiated wounds
- pressure sores.
–Musculocutaneous flaps are usually favored over muscle flaps because inclusion of a skin paddle allows for improved flap monitoring.
LOCAL RANDOM FLAPS
- Unidirectional linear advancement of tissue.
- Single advancement flap
- may be considered an extended primary closure
- utilized when defects are large and require significant tension to close
- flap is designed by making parallel incisions along a tangent to the defect
- The flap is elevated at a depth which matches that of the defect.
- Tension may be reduced by undermining the opposing wound edge.
- Additional flap advancement may be achieved by utilizing Burow’s triangles.
- Double advancement flaps
–two opposing single advancement flaps sutured at their distal edges.
–gains additional movement in exchange for two additional incisions.
–The first flap should be completely elevated before designing the second to ensure that a double advancement flap is necessary.
V–Y and Y–V advancement flap
–performed by making two linear or curved incisions from a single origin to two separate points on the border of the defect with 30° of separation
–Resulting triangle should have a length two to three times the defect diameter and a width equal to the defects greatest width
–The island of skin and subcutaneous tissue is advanced into the defect
- Can be used to repair defects that cannot be closed along a single tension vector by an advancement flap.
- Arc is extended distally from the base of the defect to a length that represents about one-fourth of a circle
- Increasing the curvature of the arc offers greater flap movement
- Pimarydefect is eliminated by flap rotationàcreates a secondary defect along the length of the arc
- Donor site is dispersed along the entire suture line
- Arc of rotation can be oversized to reduce flap tension and movement restriction at the pivot point
- May be useful in scalp, temple, cheek and trunk defects
- Long incision lines may make rotation flaps a less appealing choice in many facial locations
- Relatively simple transposition technique used to lengthen a contracted scar, breakup straight line scars and rearrange the contour of soft tissues
- Symmetry is the basis of a Z-plastydesign
- Lateral and central limb lengths & angles must all be equal to each other.
- Design produces two 30–60–90° triangles
- Pythagorean Theorem demonstrates that changing the lateral limb to central limb angle will change the length of the central axis after rearrangement
Limberg rhombic flap
- Provides a method to fill a primary defect with reduced suture line tension.
- Primary defect is converted into a four-sided parallelogram of equal lengths (x) and angles of 60 and 120°
- The modified defect serves as a template for the flap.
- An incision is performed from one of the obtuse tips extending to length (x).
- At the distal tip of this incision, a second incision with equal length (x) is made parallel to one of the near sides of the rhombus producing a 60° angle.
- flap is then lifted and transposed into the defect, redirecting the tension vector by 90°
- Narrower angle and a shorter arc of rotation
- Allows for an easier closure of the donor defect and better allocation of tension between the primary and secondary defects.
- first incision is off the short axis of the flap:
– It is the same length as the side of the rhombus.
– In contrast to the Limberg flap, the angle of this incision bisects the angle formed by the line that extends straight out from the short axis of the rhombic defect and the line created by extending a side of the rhombus from the same corner.
- The second incision is made at the distal tip of this incision and at an angle parallel to the long axis of the rhombus.
- The orientation of the second incision produces a widened pedicle, decreased tip volume and a reduced arc of rotation needed to fill the defect.
Complications of transposition flaps
- Pincushioningandtrapdooring are terms used to describe the elevation of a flap or graft above the surrounding skin.
- contraction of the curved flap edges
- excess subcutaneous fat
- oversizing the flap design
- inadequate flap tailoring
- insufficient contact between the underside of the flap and recipient bed.
- Flap necrosis:
–excess suture line tension
–ischemia associated with smoking
Free-Style Perforator Flaps
- Flap harvested on any clinically relevant perforator
- Identifying dominant perforators is based on “sound anatomic knowledge”, location is fairly predictable- along “hot spots” (iewhere there are perforators) … and doppler
- island flap that reaches recipient site through axial rotation
- Complication rates comparable to free flaps
- Usual co-morbidities nota/wcomplications
- Use perforator closest to defect for lowest arc of rotation
- Multiperforatoradvancement flap
- Circumferential incision of the deep fascia
- Large trunk, limb, inguinal, perineal, myelomeningocele, head and neck defects
- Lower Extremity Flaps
- Profunda Artery Perforator Flap (PAP)
–Perforator (s): arise from the medial branches of the profunda artery
- Proximal perforator isbtwn6-10cm from inferior gluteal crease
–Pedicle length: 8-13cm
- Local: pressure sores, vulva, perineal recon
- Free: Lower extremity, breast
- Superficial Femoral A. Perforator Flap
–Highest density in mid-thigh
–Mid and distal thigh perforators from SFA, descending genicular a., saphenous a. branches, popliteal (lots of anatomic variability)
- Pedicle Length: 5-15cm, raised like free-style
- Use: Knee: tumor, hardware coverage
- Distally based (reverse)
- Descending branch of lateral femoral circumflex
- Runs between vastus intermedius and rectus femoris
–Distal pivot point ~10cm from superolateral patella
–Uses: Trochanteric, groin, perineal, ab wall, upper/posterior thigh
- Lumbar Perforator Flaps
- Subcostal A. perforators/lateral lumbar perforators – flank and lateral posterior trunk defects
–Subcostal a. – within 3 cm of the lower costal margin at lateral border of latiss
–Lateral lumbar musculocutaneous perforators arise from posterior branches of the intercostal arteries
- Pedicled DIEP – vulvar, groin, vaginal, trochanteric defects
- Muscle SparingLatiss- based on descending branch of thoracodorsal a (not true perforator flap as 3-4 cm muscle cuff is taken)
–Middle ground between traditional latiss and thoracodorsal artery perforator flap
–Uses: Breast recon revisions (correction of contour deformity), implant salvage
–Large arc of rotation compared to true perforator flap, better preservation of NV bundle
Advances and Innovations in Microsurgery
- Perforator dissection is microsurgery too!
- Chimeric flaps- painful dissection, more degrees of freedom for inset
- Supermicrosurgery- <0.8mm anastomoses
- Lymphatic bypass (lymphovenousshunt)
–Most success in upper extremity with some patent lymph vessels
–If venous pressure > lymph pressure, thrombosis
- Vascularized LNT
–Brings healthy nodes to affected areas
–Lymphangiogesis? – via growth factors from healthy nodes
–Becomes high pressure arterial pump forcing lymph out?
–DIEP+ inguinal lymph node transfer to thoracodorsal vessels
- Fingertip Injuries- Patterns
- Reconstructive Ladder
- Healing by secondary intention
- Skin grafting
- Composite grafting
- Regional flaps
- Microsurgical replantation or reconstruction
- Skin grafting
Split-Thickness Skin Graft (STSG )
- 56% of patients considered their results good after STSG versus 90% treated by secondaryintentio
- If no bone exposed and <1.5cmàheal by secondary intention
Full-Thickness Skin Graft (FTSG )
–Consider for soft tissue defect >1 cm2
–More durable, less contraction, and greater sensibility than STSG
–Harvest graft from the thenar eminence- or antecubital fossa
–Excellent color match, hairless
–May be as wide as 2 cm
–Close donor site primarily
- The source of donor tissue is theinjured digit.
- These flaps provide immediate, near-normal sensibility.
- Donor tissue must be from outside the zone of injury.
- This method often requires a small amount of bone shortening to facilitate flap inset.
Volar V-Y (Atasoy)
- Useful fordorsal obliqueand some transverse geometry injuries
- Uses tissue adjacent to wound
- Designed with wound edge as base of triangular flap
- Can only advance distal edge1 cmunless incision carried proximal to distal interphalangeal (DIP) flexion crease
- Bilateral Triangular V-Y Advancement Flaps (Kutler)
- For _____ (volar/transverse/dorsal/lateral oblique) types of amputations
- Triangular flaps designed along lateral aspects of distal tip
- Advanced distally and centrally to cover injury
Moberg V-Y Advancement
- Blood flow in the thumb: 3 systems
–Princeps pollicis artery
- Arises from deep arch
- Divides into radial and ulnar palmar digital As
–Terminal branches of the superficial palmar arch
- Contribute to volar supply
–Distal branches of the 1st DMCA
- With branches of radial A supply dorsal thumb
- Technique is used for thumb because of unique dorsal and volar blood supply
- Radial and ulnarmidaxialincisions are made dorsal to the NV bundles, which are INCLUDED in the flap
- Flap elevation is in the plane just volar to the tendon sheath
- Flap advancement is limited to 1.0cm without additional modifications
- Incision at the baseincreasesadvancement to 1.5cm
- Thumb fingertip: VO Amputation
- Flaps from a different finger than the injured one
- Sensibility not as good as withhomodigitalflaps
- Cross finger flap:
–Useful for volar oblique injuries
–Flap raised on dorsum of injured digit’s adjacent middle phalanx and elevated just dorsal to paratenon
–Flap left pedicled to donor site along lateral margin adjacent to injured digit
–Injured finger flexed and flap inset over defect
–Flap division at 8-10 days
- Reverse Cross Finger Flap
- For_____ (volar/dorsal) injuries
- The epidermis and papillary dermis are divided and the reticular dermis andsubqtissue are used to cover the adjacent digit
- Skin flap is laid back down over the donor site and a full thickness graft is placed on the reverse flap
- HeterodigitalNeurovascular Pedicled Flaps (Littler)
- More commonly used for ulnar thumb pulp defects
- Can provide stable coverage for larger injuries compared withhomodigitalflaps
- Donor site reconstructed with skin grafting
- Dissection of ring or middle finger proper digital artery and nerve proximally to bifurcation of common digital source
- First Dorsal Metacarpal Artery Flap
- Additional option for reconstruction of volar thumb injuries
- Neurovascular pedicled flap based on first dorsal metacarpal artery
- Allows transfer of tissue from dorsum of index finger proximal phalanx
- Flap includes terminal branch of _______ to provide protective sensation
- First Dorsal Metacarpal Artery Flap
- Regional Flaps – Thenar Flap
- Used for ____ (volar/dorsal) oblique injuries of ______ (thumb/index/middle/ring/small)
- Flap division at 10-14 days
- Contraindicated in patients with RA,Dupuytren’s, elderly