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
Tissue	Skin + Fascia (optional bone + tendon)
Artery	Radial Artery
Vein	Venae comitantes of radial artery (small). Cephalic vein (optional but commonly used)
Pedicle length	Can be taken off at the bifurcation of brachial artery

Decision Making

Indications

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

Advantages

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

Disadvantages

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 Anatomy

Venous System

• 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

Nerves

• 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

Muscles

• 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 Artery

• 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 Bone

• 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 Planning

• 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 arches

Modified Allen Test

Consent

Risks

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

Alternatives

Primary closure, local flap, alternative free-flap

Surgical Instruments

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

Patient Positioning

• 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