"Square sail" flap in median nerve injuries at the wrist. Anatomy and review of twenty cases

Introduction. - Following an anatomical study on the vascular supply of the upper limb, we propose a new adipo-fascial flap at the wrist. The fat pad of pronator quadratus lies over the muscle and is vascularised by a recurrent branch arising from the anastomotic "cross-road" of the anterior interosseous, radial and ulnar arteries, at the radio-carpal joint. The peripheral extensions of the adipose tissue have to be anchored to the palmar fascia of the muscle in order to hoist the flap as a "square sail". The flap is then distally rotated in order to cover the traumatized median nerve segment at the wrist, for 2.5-3 cm of length. Methods. - The authors present a review of the clinical applications (1995-2001) on painful neuromas of the median nerve at the wrist, where traumatic and iatrogenic injuries frequently occur. The surgical procedure consists of external neurolysis followed by coverage of the nerve using this vascularised flap. Results. - The results confirm the usefulness of vascularised fat flaps in creating an optimal perineural environment in terms of biological and mechanical quality. The advantage offered by this particular local flap is that it can be speedily raised. Because of its limited length the flap is only able to cover the median nerve at the level of the carpal tunnel: its indications are therefore very selective but not rare, due to the frequency of median nerve injuries at this level. Discussion. - Clinical results were very satisfactory: in the twenty cases reviewed, resolution of the symptoms of algodystrophy and causalgia was consistently observed, sometimes to an extraordinary degree, and associated with an improvement in the neurological deficit. © 2003 Éditions scientifiques et médicales Elsevier SAS. Tous droits réservés.