{'fraction_non_alphanumeric': 0.014236902050113895, 'fraction_numerical': 0.004555808656036446, 'mean_word_length': 5.389090909090909, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Watershed Areas in Face Transplantation.

BACKGROUND
Maxillary artery has traditionally been considered the main blood supply of the facial skeleton. However, the deep and concealed location makes the harvest of facial allografts based on this artery challenging, giving preference to the facial artery. There is growing evidence that the junction between the hard and soft palate may represent a watershed area in facial artery based allografts. The aim of this study was to review the occurrence of partial allograft necrosis and modify the available craniofacial techniques allowing for a reliable harvest of maxillary artery based facial allografts.


METHODS
PubMed/Medline databases were searched for papers presenting allograft perfusion details and the occurrence of partial flap necrosis. Next, 25 fresh cadaver heads were used: 8 allografts harvested via a traditional Le Fort III approach, in 6 the maxillary artery was injected with latex, in 3 cadaver heads lead oxide gel was injected in the maxillary artery, and 8 full facial allografts were harvested through a modified approach.


RESULTS
Seven patients developed palatal fistulas or palatal necrosis (41%) when allograft was perfused via the facial artery. The traditional Le Fort III approach demonstrated consistent injury to maxillary artery/branches. The modified approach allowed for preservation of the maxillary artery under direct vision.


CONCLUSIONS
Current facial transplantation outcomes indicate that facial artery based allografts containing Le Fort III bony components can experience compromised palate perfusion. The described modified Le Fort III approach allowed the safe dissection of the maxillary artery, preserving the arterial blood supply to the facial skeleton.