Vascular and nervous anatomy of the flap
5.2 Analytical Factors and Technical Considerations
5.2.1 Venous Drainage: Superficial and Deep Vein System
Since the initial description of RFFF by Song R. in 1982, the superficial venous system was considered as the primary venous drainage of this flap [2]. The superficial venous systems are preferred by most of the surgeons for the larger diameter and thicker wall of the vessels, and a consequent easier anastomosis. Moreover, the independent and relative distant course of the cephalic vein and the radial artery, allows a simpler placement and maneuverability of both vein and artery, one to each other, in the receiving site.
It is argued which of the venous systems is the dominant one, whether the superficial or the deep one. The Ichinose et al. [3] hemodynamic study demonstrated that, at an early stage after flap elevation, the comitantes veins have twice the volume of drainage per unit time compared with the cephalic vein, and in 60% of cases, there is no obvious communication between the deep and superficial venous system.
Futran et al. [4] suggested that single venous anastomosis of the subcutaneous system provided adequate drainage of the flap reducing the operative time. The bigger concern of the supporters of the single superficial venous anastomosis is the inadequacy of the caliber of the deep veins. To overcome this limit Gottlieb et al. proposed the dissection of the pedicle up to the antecubital fossa near the confluence of the two venae comitantes [5]. In any case, the communication between the two system is absent in 40% of cases; moreover, the time of the dissection and morbidity to donor site increases, and a pedicle with an unnecessary length tends to be prone to kinking. On the other hand, the anastomosis of both drainage systems seem to reduce the venous pressure, creating a low-flow state, thus increasing the risk of venous thrombosis. Some authors suggested that the comitantes veins and the cephalic vein should be anastomosed independently on two distinct venous systems (internal and external jugular) assuring two separate and parallel drainage systems.
It is easy to note that still debate exists about which venous system prefer and whether one or two vein anastomosis give better results, probably because both the alternatives provide reliable and reproducible outcomes.
5.2.2 Sensate Flap
A sensate flap can be harvested using the LCAN. It can be anastomized in the neck with the proximal stump of the lingual nerve or more rarely with a branch of the cervical plexus. LCAN and its branches determine the most of the sensitive innervation of the RFFF, but also the medial cutaneous antebrachial nerve and the branches of the superficial radial nerve may innervate clinically relevant portions of the flap [6]. Reinnervation seems to favour sensory recovery providing larger, better arranged and more numerous nerve fibers compared to not-sensate flap [7]. Despite this, evidence about short and long term better functional outcomes with sensate flap is lacking, considering also the complexity and quantity of variables that affect recovery after reconstructive surgery [8]. On the other hand, section of the LCAN will invariably results in skin sensory deficits.
5.3 Flap Harvesting
5.3.1 Preoperative Management
At the admission, the patient and hospital personnel must be warned to avoid the violation of the nondominant forearm that must be shaved.
Although exceedingly rare, the occurrence of acute hand vascular insufficiency when harvesting a radial forearm free flap is always a possibility (two cases described in literature) and must be kept in mind.
The Allen test is the most important preoperative evaluation to assess the adequacy of the perfusion of the hand (especially the index and the thumb) through the residual ulnar artery, after forearm flap harvesting. Simultaneous digital compression of the ulnar and radial arteries is applied for few seconds by the examiner while the patient is invited to alternately open and close the hand. This pumping action causes mechanical exsanguination with the hand that becomes pale. The hand is then opened before releasing the compression on the ulnar artery. Reperfusion is evident trough a blush of the hand within 15–20 s. If a delay is noted, it can be concluded that there is not a good crossflow from the ulnar artery trough the palmar arch, representing, contraindication for proceeding with a radial forearm flap. Controlateral forearm vascular circulation should be explored.
There are no substantial differences in flaps harvested from the left or right side, so it is widespread practice to choose the donor site from the nondominant upper limb, although it is preferable to have the operating arm on the contralateral side to the resection to create more space for two surgical teams to work simultaneously. Previous intravenous lines positioning must be avoided on the side of the flap harvesting, but venepuncture itself is not an absolute contraindication. Previous surgery, scars, injury, fractures, and burns may contraindicate the use of a specific arm. Moreover, the patient’s preference is taken into account.
The patient must be counseled about the possibility of donor site sequelae and, in particular, poor cosmetic results, use of a skin graft for closure and temporary or permanent variable sensory loss of the posterolateral portion of the hand.
5.3.2 Flap Design
Right arm: identification and drawing of the radial artery, cephalic vein and flap design
5.3.3 Patient Positioning
The arm is placed 70° with respect to the patient’s body on a self-stained board. Care must be taken to minimize traction on nerves in the axilla and elbow region.
We advise the use of the tourniquet to obtain a surgical field without bleeding during the dissection. Orthopaedic cotton bandage proximally wraps the arm to avoid the prolonged contact with the inflated tourniquet. Without proper protection, the underlying soft tissue is prone to damage caused by wrinkling, pinching, or shearing.
The cuff is secured around the limb proximal to the operative site. Pressure is exerted on the circumference of the arm; when sufficient pressure is obtained, vessels and arteries beneath the cuff become temporarily occluded, preventing blood flow past the cuff. While the cuff is inflated, the tourniquet system automatically monitors and maintains the pressure chosen by the user (approximately 250 mmHg). Cuff pressure and inflation time are displayed, and an audiovisual alarm alert informs the user to alarm conditions, such as a cuff leak.
Pneumatic surgical tourniquet prevents blood flow to the arm and enables the surgeon to work in a bloodless operative field
Esmarch bandage is used to expel venous blood from the arm (exsanguinate) elevating the limb as the elastic pressure is applied
The acceptable range of tolerance to ischemia of the arm remains controversial. Tolerance of composite tissue is dependent on the quantity of contained skeletal muscle. VanderWilde et al. reported a successful hand replantation after 54 hours of cold ischemia [9].
5.4 Surgical Steps
5.4.1 Step 1
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