gms | German Medical Science

Objectives/Interrogation: Pollicisation of the index finger is the gold standard treatment for severe hypoplasia or aplasia of the thumb in radial longitudinal deficiency in children. Thumb opposition deficit is a common complication and may require abductor digiti quinti muscle or ring finger superficialis tendon transfer. We hypothesized that failure of the first dorsal interosseous muscle (FDIM) could partially explain these results. We report an original technique of FDIM pedicled flap transfer to recreate the lateral thenar muscle. Before elevating the flap, we investigated the vascular and innervation patterns of the FDIM.

Methods: An anatomical study was carried out. Fourteen fresh upper limbs were dissected to determine the vascular and innervation patterns of the FDIM. Three upper limbs were used for the description of the transfer technique.

Results and Conclusions: The point of penetration of the deep branch of the ulnar nerve (DBUN) in the FDIM was located at 41% (28-48%) from the base of the second metacarpal. Four arteries vascularize the FDIM: the direct dorsal interosseous branch, the first palmar metacarpal artery, the first dorsal metacarpal artery and the dorso-ulnar artery of the thumb. The direct dorsal interosseous branch originating from the radial artery is the major pedicle. The FDIM pedicled flap was moved backward and ulnarly-ward and, then, fixed to the anterior retinacular ligament.

The DBUN is vulnerable during the dissection of the first dorsal and the first palmar interosseous muscle in the index finger pollicization. The DBUN must be seen and protected in order to avoid its iatrogenic section. We demonstrated the feasibility of FDIM pedicled flap transfer in adult cadaver. Moving backward and ulnarly-ward the proximal insertion of the FDIM, hence recreating the lateral thenar muscle, should theoretically improve the opposition capacity of the new thumb.

Study of the anatomical vascular pattern of the hand in children with radial longitudinal deficiency must be perfomed. Clinical application is the next step toward confirming the reliability and efficiency of FDIM pedicled flap transfer.