The oblique branch trap in the harvest of the anterolateral thigh myocutaneous flap.

A 67-year-old man with squamous cell carcinoma underwent reconstruction with a free anterolateral thigh myocutaneous flap. Unroofing the skin perforators found that the skin perforators originated from the oblique branch of the lateral circumflex femoral artery with no connections with the descending branch. Thus, the flap was harvested based on the oblique branch, leaving the descending branch in situ. Reconstruction was completed uneventfully and he had an excellent outcome at 1-year follow-up. The anterolateral thigh myocutaneous flap was reputed to be a technically easy flap to harvest. The perforators supplying the skin were visualized and a block of muscle incorporating the perforators harvested with the descending branch of the lateral circumflex femoral artery as the pedicle of the flap. However, not infrequently with this approach, the flap thus harvested has a well-perfused muscle component, whereas the skin component was not viable. This situation is explained anatomically by the potential occurrence of an alternative pedicle that supplies the anterolateral thigh flap, called the oblique branch of the lateral circumflex femoral artery. Our case presented here was a "classic" intraoperative finding of this potential trap and the importance of defining the anatomy before committing oneself to the harvest by unroofing all the skin perforators was emphasized.