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the Gracilis Flap

A long and thin muscle, the gracilis provides a reliable workhorse for reconstructive microsurgery. Both for wound coverage, and as a functional muscle transplant, the gracilis has wide reconstructive applicability. The intramuscular neural anatomy allows the muscle to be thinned segmentally, allowing excessive bulk to be trimmed as needed before functional muscle transplantation. 

The muscle width varies with the size of the patient, and is generally wider in men, and physically fit patients. It can be used to cover wounds roughly up to 6 cm wide and 20 cm long. It has broad applicability in both lower and upper extremity reconstruction and in functional muscle reconstruction after paralysis or muscle loss.

Anatomy

A medial thigh muscle, the gracilis takes origin off the pubic symphysis, inferior pubic ramus and ischium then inserts distally into the medial condyle of the knee. The axis of the muscle can be outlined by drawing a line from the ischium to the knee medial condoyle. Or alternatively, the adductor longus is palpated medially with the thigh abducted, and the gracilis axis is defined 2 to 3 fingerbreadths posterior to the adductor longus.

Vascular Anatomy

The afferent artery and efferent veins run superficial to the adductor magnus muscle, underneath the addutor longus. By retracting the adductor longus, the artery can be traced to it's origin on the medial femoral circumflex vessels, branches of the profunda femoral system. There are two secondary pedicles to the gracilis muscle, that can be found segmentally and distal to the proximal pedicle. The are both ligated and divided when the muscle is harvested. With extremely short leashes, they are not used for revascularizing the gracilis as a free flap.

Note in the figure below that the nerve branches into three segments to supply the anterior, mid and posterior segments of the muscle. This arrangement is valuable for thinning and debulking the muscle.

Flap Harvest

The patient is placed supine, with the leg prepped entirely free to the groin. The thigh is abducted and the knee slightly flexed. The axis of the muscle is marked posterior to the adductor longus by two the three fingerbreadths. Because the pedicle enters the muscle approximately 10 centimeters below the ischium, the incision markings need to take this into consideration. An optional distal incsion is made near the muscle insertion at the knee to transect the distal tendon if the entire length of the flap is needed.

The proximal incision is carried down through the fat and the muscular fascia to the muscle. The fascia is elevated off the muscle anteriorly and the septal junction of the gracilis and addutor longus is identified. This space is then entered by retracting the two muscles from each other and the pedicle to the gracilis is identified in this areolar plane. The pedicle can be isolated at this point or further muscle dissection may be peformed now that the vascular supply has been safely located an protected.

The muscle is then freed of all soft tissue attachments except for the pedicle. The proximal tendon is cauterized to detatch it from the ischiopubic ramus and the distal muscle is transected with cautery near the insertion or at the distal wound, depending on the length needed. The nerve is transected - long if a functional muscle is being transplanted, or short if length is not necessary.

The wound is closed in layers over a suction drain. The patient is allowed to ambulate when clinically acceptable for the recipient site area.

Post-Operative Care

The ankle is splinted in neutral and the patient is allowed to ambulate in a cast shoe at about a week after surgery, usually with an ace wrap to prevent edema.  At all other times the foot is kept elevated.  The donor site can heal slowly if closed under tension or in the elderly patient.