Radial Forearm Free Flap

  • Distal skin paddle of the forearm commonly used in head and neck surgery
  • It is an extremely versatile flap allowing intricate folding of the skin, using two or more skin paddles/ islands, and incorporating vascularised tendon and/or bone (osteocutaneous flap)
Radial Forearm Free Flap
Quick Facts
TissueSkin + Fascia (optional bone + tendon)
ArteryRadial Artery
VeinVenae comitantes of radial artery (small). Cephalic vein (optional but commonly used)
Pedicle lengthCan be taken off at the bifurcation of brachial artery

Decision MakingEdit

IndicationsEdit

Common reconstructive applications include:

  • Floor of mouth, tongue, soft and hard palate, buccal mucosa, pharynx and oesophagus
  • Lips
  • Orbit
  • External skin defects
  • Incorporating part of radius as osteocutaneous flap for premaxillary, maxillary, nasal, and selected mandibular defects
  • Incorporating palmaris longus tendon sling to support lower lip reconstruction

AdvantagesEdit

  1. Very pliable, thin skin, especially at distal forearm (one of thinnest skin flaps)
  2. Usually very little soft tissue bulk
  3. Large flap may be harvested (30 x 15cm)
  4. Multiple skin islands can be used
  5. Sensory innervation possible
  6. Can incorporate radius bone or tendon
  7. Easy flap elevation
  8. Large, reliable, constant vessels
  9. Long pedicle usually available
  10. Distant location of donor site from head and neck resection permits simultaneous harvesting and resection
  11. Large distal size of vessel allows it to be used as a "flow-through-flap" for an additional flap to be attached distally

DisadvantagesEdit

  1. Potentially poor skin quality: in certain individuals the flap may be quite bulky, especially proximally; this can compromise certain reconstructions
  2. Donor site morbidity: loss of skin graft and tendon exposure; visible donor site and possible poor cosmetic result
  3. Vascular: atherosclerosis (seldomly); postoperative vascular compromise of hand (rarely)

Surgical AnatomyEdit

Venous SystemEdit

 
  • Main superficial veins of the forearm (cephalic and basilic veins) lie deep to the fatty layer of the forearm (small venous tributaries may be found in subcutaneous tissue)
  • Cephalic vein - most commonly used single vein for venous drainage of RFFFs
    • Large + thick- walled
    • Relatively constant location deep beneath the subcutaneous fat
    • Drains the anterolateral forearm
    • Pathway:
      • Formed by the confluence of superficial veins on the dorsal aspect of the hand
      • Vein then traverses the "snuffbox" area to lie over the lateral side of the distal forearm
      • Then courses more medially towards the mid-lateral cubital fossa
    • Associated structures:
      • Accompanied by the lateral antebrachial nerve
      • The superficial branch of the radial nerve lies in close proximity to the vein in the distal third of the lateral forearm and over the "snuffbox” area up to the lateral aspect of the dorsum of the hand
    • Be aware that it is often used for IV access - may cause fibrosis and/or thrombosis of the vessel
  • Basilic vein
    • Runs on medial aspect of forearm
  • Median (antebrachial) vein of the forearm
    • Lies between cephalic and basilic veins
    • Usually thin walled and more superficial in subcutaneous fat layer when compared to cephalic
    • Occasionally it may be large and be a better drainage system to use for a flap
  • Large variety of venous interconnections may be encountered in the cubital fossa
    • The median cubital vein - runs obliquely from lateral to medial to connect the cephalic and basilic systems
    • Usually there is a connection between the superficial veins and the deep brachial venous system in the cubital fossa (this is usually between the brachial venae comitantes and the median cubital vein or the cephalic vein)
  • The forearm and cubital fossa are invested by the deep fascia
    • In the cubital fossa it is strengthened by the bicipital aponeurosis
  • The perforating vein connecting the superficial and deep venous systems lies lateral to the bicipital aponeurosis and the brachial vessels immediately deep to it

NervesEdit

  • Superficial nerves accompany the superficial veins
    1. Superficial branch of the radial nerve - close to cephalic vein in "snuffbox" region
    2. The lateral antebrachial nerve - termination of musculocutaneous nerve (found between the flexor carpi radialis and palmaris longus tendons)
    3. Palmar cutaneous branch of the median nerve - arises just above the flexor retinaculum becoming cutaneous between tendons of palmaris longus and flexor carpi radialis
      • Elevation of a very distal skin flap may injure this branch and cause sensory loss of the proximal mid-palm

MusclesEdit

 
  • Radial artery runs in the lateral inter-muscular septum which separates the flexor and extensor compartments of the forearm
    • Medially are the flexor carpi radialis (FCR) and the other forearm flexor muscles
    • Laterally is the extensor compartment
  • Important muscular relations to radial artery:
    • Proximal third of forearm:
      • Superficial to supinator, pronator teres and flexor digitorum superficialis (FDS)
    • Distal third of forearm:
      • Superficial to flexor pollicis longus (FPL) and pronator quadratus
      • At the wrist the radial artery lies between the brachioradialis and flexi carpi radialis tendons
  • Brachioradialis
    • Key muscle when elevating this flap
    • The muscle overlies the anterolateral side of the artery
    • It is supplied by the radial nerve of the extensor compartment, even though it is an elbow flexor
    • Bulky muscle belly lies anterior to, and covers, the radial artery in the proximal half of the forearm
    • In the distal forearm the muscle becomes a flat tendon (tendon commonly covers the artery either partially or completely)
  • Palmaris longus
    • Tendon can be sacrificed without causing a functional deficit
    • It is absent in around 13% of individuals
    • Its tendon and muscle can be incorporated in a forearm flap for various reconstructive possibilities and it may therefore be an extremely valuable adjunct in complex reconstructions

Radial ArteryEdit

 
  • The brachial artery bifurcates into ulnar and radial arteries
  • Pathway of radial artery:
    • Radial artery starts in the medial cubital fossa (1cm distal to the elbow crease, just medial to the biceps tendon)
    • Then courses down the forearm in the lateral intermuscular septum (which separates the flexor and extensor compartments of the forearm)
    • The radial artery courses down the forearm between the flexor carpi radialis and the brachioradialis (in lateral intermuscular septum)
    • Terminated in the deep palmar arch
  • Branches in the forearm:
    • Radial recurrent artery close to its origin and distally
    • Palmar carpal branch
    • Superficial palmar branch
    • Dorsal carpal branch (continuation of artery)
    • Also giver off numerous muscular branches
  • Septocutaneous perforators:
    • Branches that supply the overlying fascia and skin
    • Variable number (~12) - more in distal ⅓ of forearm
    • Major perforator is usually found ≤2cm of the radial styloid process
  • Periosteal blood supply to the distal radius is via branches to the deep flexor pollicis longus and pronator quadratus muscles; perforators also pass through the lateral intermuscular septum from the radial artery to the periosteum

Radius BoneEdit

  • The distal 10 - 12cm of the anterolateral radius can be harvested as an osteocutaneous radial forearm free flap
  • The shaft of the radius increases in size from proximal to distal and bows laterally
  • The medial side of the shaft has a sharp interosseous border at the attachment of the interosseous membrane
  • The wide distal end tapers into the pyramidal styloid process

Pre-operative PlanningEdit

  • Harvesting the radial artery is associated with a remote possibility of vascular compromise causing claudication of the hand
  • Confirm the presence of a radial arterial pulse
  • Enquire about the patient’s occupation or leisure activities e.g. a pianist may be concerned about claudication
  • Reynaud's disease is a pertinent medical condition
  • Choice of arm depends on:
    • Patient preference (usually contralateral to dominant hand)
    • Previous IV lines, surgery, injury, scars, fractures or vascular compromise
    • Ideally contralateral side to the resection to create enough space for 2 surgical teams

Assessment of palmar vascular archesEdit

Modified Allen Test

ConsentEdit

RisksEdit

Pain, infection, bleeding, bruising, swelling, scar (normal/hypertrophic/keloid), poor cosmetic result, delayed wound healing, failed free flap, failed skin graft to donor site, temporary or permanent sensory loss to hand (radial thenar region, metacarpal region of the dorsum of thumb or less commonly, of the dorsal hand), temporary or permanent stiffness/reduced function to hand, claudication

AlternativesEdit

Primary closure, local flap, alternative free-flap

Surgical InstrumentsEdit

  • Tourniquet
  • Shaver (if hair removal is needed)
  • Arm table

Patient PositioningEdit

  • Resection + elevation of flap can be done simultaneously as a 2-team approach to minimise the length of surgery
  • Keep anaesthetic and other equipment at the foot of the bed to create more space
  • Two bipolar and monopolar electrocautery systems are required
  • Place the arm on an arm table
  • Avoid hyperextending or hyperabducting the shoulder
  • Shave the forearm
  • Apply a tourniquet to the upper arm
  • Adjust the operating table and/or the chairs so that the reconstructive surgeon and assistant are seated

Skin MarkingEdit

 
The flap outline is marked on the skin together usually with a proximal lazy S extension of the incision toward the antebrachial fossa. Pathway of cephalic and radial artery can also be marked. The flap is usually positioned distally on the forearm flexor surface where the skin is thin, pliable, and relatively hairless. Most intraoral defects are reconstructed with flaps of 7cm × 5cm.UCT Head & Neck

Surgical StepsEdit

  • A tourniquet is placed on the upper arm and inflated to a pressure of 1.5x patient’s systolic pressure (usually 250 mmHg)
  • The tourniquet should not be applied for more than 60 min

Subfascial flap elevationEdit

 
Step 1: Incise the circumference of the skin flap and the proximal curvilinear ex-tension towards the cubital fossa with a No. 15 scalpel blade. Elevate the flap with a scalpel from laterally in a deep subcutaneous (not subdermal) plane until the cephalic vein which lies deep to the subcutaneous fat comes into view. UCT Head & Neck
 
Step 2: Using a scalpel, elevate the cephalic vein from lateral-to-medial with the intervening subcutaneous tissue between vein and flap. UCT Head & Neck
 
Step 3: Elevate and skeletonise the cephalic vein proximal to the flap. The lateral antebrachial cutaneous nerve accompanies the cephalic vein in the same subcutaneous plane. If an innervated flap is planned, this nerve is elevated with the cephalic vein. UCT Head & Neck
 
Step 4: Separate the vein without its surrounding soft tissue from the main vascular pedicle using sharp scalpel dissection. Elevate the lateral aspect of the flap in a subfascial plane over the extensor and abductor tendons with a No. 15 scalpel blade. Identify the superficial branch of the radial nerve lateral to the brachioradialis and medial to the extensor pollicis brevis and abductor pollicis longus. UCT Head & Neck
 
Step 5: Extend the dissection medially over the epitenon covering the latter two tendons and the radial nerve, until the flat tendon of brachioradialis is visualised. It is very important to maintain epitenon over these tendons to provide a "cover" for skin grafting, if required. UCT Head & Neck
 
Step 6: Carefully continue with sharp dissection over the brachioradialis tendon up to its sharp medial edge. To retract the brachioradialis muscle and tendon, the assistant stands on the radial side of the arm and the surgeon sits next to the trunk of the patient where he/she is protected from physical interference by the resection team. While the assistant applies lateral traction to the muscle with skin hooks, release the medial edge of the brachioradialis muscle off the (poorly defined) underlying lateral intermuscular septum using sharp dissection. Sharply dissect and elevate the tendon superiorly up to its musculotendinous junction; the radial artery generally lies immediately below the tendon; therefore, the angle of the scalpel blade is changed to a horizontal plane to cut along the under surface of the brachioradialis tendon. UCT Head & Neck
 
Step 7: Distally, the perforators commonly hook around the medial edge of the brachioradialis tendon where they are vulnerable to injury, especially when incising perpendicularly past the medial edge of the tendon. UCT Head & Neck
 
Step 8: Incise the fascia overlying the muscle lateral to the vascular pedicle. UCT Head & Neck
 
Step 9: Once the brachioradialis muscle has been mobilised, the full length of the radial artery is visible and the likelihood of injuring the perforators is much less. UCT Head & Neck
 
Step 10: Ligate and divide larger muscle perforators and coagulate small ones with bipolar. UCT Head & Neck
 
Step 11: Next elevate the medial side of the flap by cutting the epimysium covering the wrist flexor muscles with a scalpel. Elevate the deep fascia over the tendons, but preserve the epitenon covering the tendons. Elevate beyond the flexor carpi radialis and incise the deeper muscle fascia over the flexor digitorum superficialis muscle. UCT Head & Neck
 
Step 12: Incise the fascia over the radial artery and isolate the artery and venae comitantes. UCT Head & Neck
 
Step 13: Ligate and transect the artery and venae comitantes. UCT Head & Neck
 
Step 14: Dissection now proceeds from distal- to-proximal. UCT Head & Neck
 
Step 15: Meticulously divide the side-branches along the artery until enough vessel length is achieved to reach the recipient vessels in the neck; this permits drainage of both the superficial and deep venous systems via a single venous anastomosis. UCT Head & Neck

Vein selectionEdit

  • The cephalic vein may be divided at any point along its course
  • The cephalic vein may be dissected into the cubital fossa where connections may exist between one (or both) branches of the venae comitantes of the radial artery and, more commonly to the median cubital or the cephalic veins
  • More rarely the deep and superfi- cial systems are anastomosed separately, utilising the cephalic and one of the large cubital veins
  • Occasionally a very large dominant median vein of the forearm can be used
  • Some avoid using venae comitantes for anastomoses, due to their small size

Flap disconnection and donor site closureEdit

  • Deflate the tourniquet
  • While awaiting reperfusion of the flap vasculature, the surgeon prepares the recipient vessels in the neck
  • Control bleeding side-branches on the pedicle and on the flap with bipolar coagulation and/or clips before disconnecting the flap from its blood supply
  • Attempt to advance skin to cover exposed tendons
  • If primary closure is not possible (usually the case) a skin graft is required
  • Skin grafts:
    • Maintain epitenon over tendons
    • Bury tendons by oversewing with deeper muscles
    • Fix and immobilise skin grafts with sutures and dressing
    • Volar splints should be applied to restrict movement of flexor tendons beneath skin graft
  • Common sites for skin grafts:
    • Inner upper arm
    • Outer upper arm
    • Thigh
    • V-Y skin graft

Post-operative careEdit

  • Graft is covered by a compression packing for at least 10 days
  • Volar splint for 2 weeks

Follow-upEdit

ComplicationsEdit

  • Long-term morbidity is often considered relatively minor and of secondary importance to oncology patients
  • However, prolonged wound healing is inconvenient and may occasionally lead to significant morbidity
  • Loss of skin graft
    • Not uncommon to lose <25% of skin graft + for late wound breakdown to occur - both generally not considered graft failure and can be managed conservatively
    • True graft failure can range from 10-20%
  • "Biomechanical morbidity"
    • Functional compromise and reduction in grip strength (10-20% weaker)[1]

ReferencesEdit