Functional gracilis flap in thenar reconstruction

Restoration of lost opposition in the context of significant thenar soft tissue defects represents a tremendous reconstructive challenge. Free functioning muscle transfer has been described in this context and has the advantage of providing both a functioning muscle unit as well as soft tissue coverage in a single reconstructive procedure. It adds to the injured limb, and by sparing donor tendons avoids the need for re-education of motor function. We describe the use of a free innervated gracilis muscle flap for functional thenar reconstruction in two unique cases following extensive traumatic loss of thenar skin and musculature. Crucially, in each case, the recurrent motor branch of the median nerve had been destroyed at its point of insertion into the thenar muscle remnants.

To date, the main reported disadvantages of free functioning muscle transfer in thenar reconstruction include difficult flap dissections, donor site morbidity, inadequate strength and excursion of the transplanted muscle and excessively bulky flaps. Our aim was, as far as possible, to address these issues.

Each thenar defect was measured and a corresponding segment of gracilis muscle, measured in situ, was raised on the proximal neurovascular pedicle. End-side microvascular anastomosis was performed between the medial circumflex femoral artery and the radial artery. The venae comitantes of the pedicle were anastomosed end-end with those of the radial artery and also with the cephalic vein. Epineural anastomosis was performed between the motor branch of the obturator nerve and the recurrent motor branch of the median nerve. Each flap was covered with a split thickness skin graft.

Both flaps survived without any complication. Both patients regained excellent voluntary thumb opposition, sufficient to allow return to full-time employment, and had restoration of sufficient thenar bulk. This was achieved with minimal donor site morbidity.

Restoration of lost opposition, in the context of significant thenar soft tissue defects, can be achieved using a free functional gracilis flap. This produces clinically excellent functional results and can be carried out as a single stage reconstructive procedure. This is a novel application of a tremendously versatile donor muscle in functioning free muscle transfer.