Lateral Arm Flap for Hand and Wrist Coverage

Michael Sauerbier

Goetz A. Giessler

The first description of the lateral arm flap was by Song and coworkers. They used it primarily as a free microvascular flap for small and medium-sized defects in reconstructive procedures of the head and neck. A detailed study by Katsaros et al later popularized it as an extremely versatile, easy to harvest septocutaneous flap with relatively low donor site morbidity. The vascular anatomy is reliable, and the dissection is rather quick and can be performed under regional anesthesia for reconstruction of hand and wrist defects. To date, the flap is used for a wide spectrum of defects all over the body.

The shortcomings of the original lateral arm flap were the flap’s bulkiness and a pedicle of moderate length when skin flaps were centered over the middle aspect of the lateral arm. Recent anatomic studies have led to significant modifications in flap design; the skin paddle is now centered over the lower third of the upper arm extending to the lateral epicondyle (extended lateral arm flap). This produces a thin flap with a long pedicle length. The flap may also be used in a reversed fashion (reversed lateral arm flap) or as a pedicled antegrade V-Y flap (extreme lateral arm flap). A pure fascial flap has also been described. The flap may be designed to include vascularized nerve, tendon, and bone. This versatility has made the lateral arm flap a “workhorse” for elective, urgent, and emergency reconstructions of the hand and wrist.

Indications/Contraindications

Indications

The lateral arm flap has a wide range of applications for closure of small and medium-sized defects in hand and wrist surgery. The classic fasciocutaneous or fascial flap serves well for reconstruction of the dorsal aspect of the hand or the thumb index web space. Patients with a thin subcutaneous fat layer are the best candidates for the flap because it is soft and easily pliable for complex three-dimensional defects.

For cases of palmar reconstruction, we prefer to use a fascial flap, as the cutaneous lateral arm flap may be too thick. This flap is then covered with a full thickness graft and made sensate by anastomising the posterior cutaneous forearm nerve to the palmar branch of the median nerve. Defects with loss of extensor tendons or metacarpal bone can be closed using a composite lateral arm flap using a distal humeral cortical segment and/or a vascularized triceps tendon graft. For all these indications, the flap has to be used as a free microvascular flap. The pedicle is long enough (see following) for flap positioning around the hand or wrist in many cases. The main alternatives to the lateral arm flap are the (osteo-) cutaneous scapular/parascapular, radial forearm, enterolateral thigh flap, and dorsalis pedis flaps. The specific features of each are provided in Table 15-1.

Contraindications

The free lateral arm flap represents a microsurgical procedure of considerable length. Patients with poor general health who need an elective procedure should be optimized preoperatively; otherwise,
other treatment options should be considered. Previous trauma or surgical procedures in this area, such as plate osteosyntheses of the humerus, probably have destroyed the perforators and are a contraindication. Patients with considerable body fat provide a bulky lateral arm skin flap which is unsuitable for most hand and wrist reconstruction. Using the fasciocutaneous lateral arm flap together with a skin graft can be an option in these cases. The relatively conspicuous scar of the lateral arm flap poses a relative contraindication in female patients. Whenever the donor site cannot be closed primarily, other flap options should be thought of (see previously). Hair transfer may pose a problem in head and neck reconstructions. Likewise, male patients may prove a challenge with hair transfer in hand and wrist reconstructions.

Table 15-1. Comparison of the Lateral Arm Flap to Possible Alternatives for Simple or Composite Reconstructions at the Hand and Wrist

	Lateral Arm Flap	Radial Forearm Flap	Anterolateral Thigh Flap	Scapular Parascapular Flap	Dorsalis Pedis Flap
Max. skin island size (cm)	8 × 25	10 × 20	7 × 25	15 × 28	5 × 8
Max. pedicle length (cm)	11	15	15	10	8
Fascia only	Yes	Yes	—	—	—
Tendon component	Lateral triceps tendon	Palmaris longus, half of the radial carpal flexor	Fascia lata	—	Short toe extensors
Muscle component	—	—	—	Latissimus dorsi, anterior serratus	No
Bone component	Distal humerus	Distal radius	—	Lateral scapular border	2nd metatarsal
Nerve component	Posterior cutaneous forearm nerve	Lateral antebrachial cutaneous nerve	Lateral femoral cutaneous nerve	—	Superficial peroneal nerve
Patient positioning	Supine or lateral prone	Supine or lateral prone	Supine	Lateral prone	Supine

Anatomy

The skin on the upper lateral arm receives its perfusion by septocutaneous perforators in the lateral intermuscular septum inferior to the tip of the deltoid muscle. They originate from two main branches in the middle of the upper arm between the acromion and the lateral epicondyle originating from the profunda brachii artery. Those main branches are called the anterior and posterior radial collateral arteries (ARCA and PRCA), with the latter having a reliable longitudinal network along the septum to distal arteries. The PRCA is the nourishing artery for the lateral arm flap as it runs close the humerus in the septum between triceps brachii and the brachial muscle. The ARCA branches off between the brachial and brachioradial muscles and is ligated during flap elevation. In rare cases (about 6%), the PRCA is found to be duplicated. On its way distally to the plexus around the elbow, the PRCA gives off three to five septocutaneous perforators serving as feeder vessels for the lateral arm fascia or fasciocutaneous flap. Those surfacing perforators are easily visible during flap dissection. After reaching the subcutaneous plexus, the branches run both anteriorly and posteriorly. In this region, the PRCA anastomoses with the interosseus recurrent artery (between the lateral epicondyle and the olecranon), the recurrent radial artery (anterior to the lateral epicondyle directly above the periosteum), and the inferior ulnar collateral artery to this plexus. These multiple arterial connections allow for distal extension of the skin paddle, which can be harvested up to 12 cm distal to the epicondyle. These anastomoses also allow for the use of the flap in a reverse fashion using one of the perforators from this periarticular plexus.

The venous drainage of the lateral arm flap is by veins of the PRCA together with a rich network of subcutaneous veins including the cephalic vein, which may be included in the anterior part of
larger flaps. The cephalic vein does not need to be included in smaller flaps necessarily, but can provide adequate additional venous drainage in larger or composite flaps.

Depending on flap positioning, the overall pedicle length can reach up to 11 cm in the authors’ experience, with the artery having a diameter of 2 to 2.5 mm at its proximal origin from the brachial artery.

Bone, tendon, and nerve may be included within the lateral arm flap and used for reconstruction of composite defects. A strip of vascularized bone may be harvested from the distal, epicondylar section of the lateral humerus. Detailed studies have shown one to four nutrient vessels from the PRCA to the bone. These vessels enter the lateral humeral aspect 2 to 7 cm proximal to the lateral epicondyle. Fifty percent of the triceps tendon may also be harvested with the flap, resulting in a maximum tendon graft of 10 × 2 cm. Gosain et al demonstrated by injection studies that the blood supply to this strip is not via the lateral intermuscular septum, but rather through the triceps muscle. Thus, a cuff of muscle must be included to have a vascularized tendon segment; alternatively, an avascular triceps tendon autograft may be dissected with the flap if one does not wish to violate the triceps muscle. Finally, the posterior cutaneous forearm nerve can be included within the flap allowing for the possibility of a sensate free flap. Harvest of this nerve will result in a strip of distal forearm numbness postoperatively.

Preoperative Planning

Doppler examination can be used for centering the skin paddle over the vascular pedicle. The flap can be harvested in regional anesthesia using a sterile tourniquet (250–300 mm Hg). For a transplantation to the contralateral arm, general anesthesia is adequate. Loupe magnification for flap dissection is strongly recommended (2–4.5 times). The standard lateral arm flap is centered over a virtual axis between the tip of the deltoid muscle and the easily palpable prominence of the lateral epicondyle of the humerus (Fig. 15-1). When marking this axis in patients who are obese or with very mobile skin, the surgeon has to support redundant tissue of the posterolateral upper arm, as gravity might pull the tissues posteriorly, endangering pedicle inclusion. When flap design is continued beyond the lateral epicondyle, the central axis of the flap is continued distally from the lateral epicondyle in the direction of the distal radioulnar joint on the wrist dorsum. Harvesting the flap from the distal humerus and dorsal forearm produces a thinner flap than flaps raised at the midhumeral level. The reversed or extreme lateral arm flaps have their major indications as a pedicled flap for defect closure around the elbow and proximal forearm.

In planning a composite lateral arm flap, a precise idea about the future positioning of the several components at the recipient site is mandatory. If an osteocutaneous flap is dissected, it should be centered at the distal upper arm, as the receivable bone graft has a maximum length of about 10 cm from the lateral epicondyle proximally. It should not be wider than 25% of the humeral circumference, which is sufficient for most indications at the hand and wrist.

Only gold members can continue reading. Log In or Register to continue