Reconstruction of thenar eminence defects using modified medial pedis flap combined with abductor hallucis muscle transfer

Objective To explore the surgical technique of functional myocutaneous flap transfer for reconstruction of the appearance of the thenar eminence and thumb opposition,and to improve the design and harvest of medial pedis myocutaneous flap.Methods From November 2010 to January 2012,6 cases with skin and muscle defects of the thenar eminence were treated by modified medial pedis flap combined with abductor hallucis muscle transfer using microsurgical techniques.Functional exercises and physical therapy were initiated 3 weeks postoperatively.Electromyogram (EMG) of the thenar muscles was performed at 6 and 12 months after the transfer.Grip strength,pinch strength,British Medical Research Council (BMRC) muscle strength and sensory recovery grading were performed during the follow-up periods.Results Flaps in all cases survived well.The appearance of the flaps was similar to the normal skin of the hand.All cases had more than 12 months' followup.In all cases,voluntary abduction of the thumb by the transferred abductor hallucis was achieved and confirmed by EMG.EMG of the thenar muscles at 6 months showed a mixed pattern upon maximum voluntary contraction and an interference pattern at 12 months.Pain and touch perception returned at 6 months,while twopoint discrimination was 7.5 to 11.2 mm (mean,7.9 mm) at 12 months.BMRC sensory grading was S3+,while muscle power recovery was M3 to M4.Conclusion As a new myocutaneous flap,the modified medial pedis flap combined with abductor hallucis muscle transfer is effective for repairing thenar eminence defects.The flap had not only good appearance and sensory reinnervation,but also the transplanted hallucis abductor muscle results in satisfactory opposition function of the thumb once it is innervated. Key words: Surgical flaps;  Clinical research;  Medial pedis flap;  Hallucis abductor muscle; Thenar eminence