Radial Artery Forearm Flap
Anatomy
A fasciocutaneous flap is supplied by the radial artery and drained by the superficial (cephalic) and deep (vena comitans) venous system.
Flap Design
It is designed to fit the defect. Identify cephalic vein, lateral intermuscular septum, FCR and brachioradialis.
Flap Elevation
From proximal to distal between the antebrachial fascia and the muscle belly fascia/paratenon. Retract brachioradialis laterally to identify vascular pedicle in the lateral intermuscular septum.
Discussion
A versatile and reproducible flap with relatively constant anatomy. It's limited by sacrificing a major vessel in the arm and donor site wound healing issues.
Anatomy of the Radial Artery Forearm Flap
Key Point
The radial artery forearm flap is a fasciocutaneous flap supplied by the radial artery and drained by the superficial (cephalic) and deep (vena comitans) venous system.
Flap Composition
The radial artery forearm flap is a fasciocutaneous flap that can be harvested with different compositions.
This flexibility is because the radial artery provides perforators that pierce antebrachial fascia and supply skin, fat, fascia, muscles, tendons, nerves and bone.
Composition options include:
- Suprafascial cutaneous flaps
- Adipofascial cutaneous flaps
- Osteofasciocutaenous (distal radius segment leaving dorsal & radial cortices)
- ± tendons of palmaris longus, brachioradialis, flexor carpi radialis
Arterial Supply
The radial artery forearm flap is supplied by the radial artery.
The radial artery originates from the brachial artery deep to the bicipital aponeurosis to give a pedicle length of ~20cm long and ~3mm wide. Key landmarks during its distal course down the lateral intermuscular septum include:
- Proximal forearm: between brachioradialis & pronator teres
- Distal forearm: between brachioradialis & flexor carpi radialis.
- Wrist: posterior to APL and EPB to enter snuffbox
- Hand: between 1st/2nd metacarpals to form the deep palmar arch.
Venous Drainage
The radial artery forearm flap's main venous drainage is through the superficial system (cephalic) and the deep system (venae comitans). A decision has to be made on whether to preserve the cephalic vein or use it as part of the venous drainage of the flap.
In relation to the venae comitantes:
- 2 vessels parallel to the radial artery
- ~2mm in diameter, ~16cm in length and contain valves.
- Joins with superficial vessels (cephalic & basilic) via the median cubital vein
In relation to the cephalic vein:
- Superficial vein
- Similar length but slightly wider diameter than venae comitantes
- Located between the brachioradialis and biceps at the elbow.
Flap Innervation
The radial artery forearm flap is innervated by cutaneous nerves. Motor innervation is generally not required as it is not typically used for a muscle flap.
- Lateral antebrachial nerve: lateral half of the volar forearm.
- Medial antebrachial nerve: medial half of the volar forearm.
Design of the Radial Artery Forearm Flap
Key Point
The skin paddle is designed to fit the defect. Consider arm protection and Allen's test. Identify cephalic vein, lateral intermuscular septum, FCR and brachioradialis.
- Avoid intravenous or arterial lines that may impact the flap vascularity
- Allen's test to determine the continuity of the palmar arch and any potential radial-sided vascular insufficiency
- Identify lateral intermuscular Septum, cephalic vein and brachioradialis.
- Palpate or Doppler the Radial Artery
- Visualise superficial veins: cephalic may be needed for venous anastomosis and also identifies the location of the lateral cutaneous nerve.
- Design your skin paddle: avoid the ulnar subcutaneous border as the radial artery supplies this area the least.
Elevation of the Radial Artery Forearm Flap
Key Point
From proximal to distal between the antebrachial fascia and the muscle belly fascia/paratenon. Retract brachioradialis laterally to identify vascular pedicle in the lateral intermuscular septum.
- Inflate the tourniquet after insanguination
- Incise the skin paddle. Starting radial or ulnar is a surgical preference.
- Proximal extension of the incision should dermis-only to allow a subcutaneous elevation of forearm and preservation of the superficial venous system.
- Elevate between the antebrachial fascia and muscle belly fascia or paratenon of the FCR & palmaris longus.
- Identify the cephalic vein and superficial branch radial nerve distally.
- Ligate ligate the radial artery and venae comitans distally.
- Retract the brachioradialis laterally to access the lateral intermuscular septum. Be careful to preserve the more proximal fasciocutaneous perforators.
- Dissect flap from its deep structures but keep attached to its pedicle and surrounding tissue. The pedicle dissection along the intermuscular septum is continued to the level of the brachial artery.
- Release tourniquet to perform hemostasis and inspect vascularity of the hand.
- Perform a donor site closure, usually with a split-thickness skin graft.
Discussion on the Radial Artery Forearm Flap
Key Point
The radial artery forearm flap is a versatile and reproducible flap with relatively constant anatomy. It's limited by sacrificing a major vessel in the arm and donor site wound healing issues.
Advantages
- Relatively constant and reproducible vascular anatomy based on large vessels.
- Versatile flap composition (skin, fat, fascia, bone and tendon)
- Versatile in shape and design due to thinness and pliability.
- Can easily be used as a free, pedicled or flow-through flap.
- Venous anastomosis options as superficial and deep venous systems communicate.
- Radial artery provides a long pedicle.
Disadvantages
- Pooor donor site healing with potential functional and cosmetic issues
- Bone harvesting can result in fracture
- Sacrifices major artery of the arm.
