Ring Finger Flexor Digitorum Superficialis Hemi-Tendon Transfer for Fifth Finger Flexor Digitorum Profundus Reconstruction Technique: Preliminary Cadaveric Study and Case Report.

Delayed tendon injury has been historically treated with several techniques, including staged tendon graft and flexor digitorum profundus (FDP) transfers from neighboring rays. Nevertheless, the use of the flexor digitorum superficialis (FDS) hemi-tendon from neighboring fingers may provide the same results with less donor site morbidity. This article aims to present the safety and effectiveness of the fourth FDS hemi-tendon transfer technique to treat zone I-5th FDP injuries on cadaver specimens, and to describe its in vivo application. In 4 fresh-frozen forearms, the fifth FDP was cut at zone I. All the fourth and fifth finger pulleys, except for A2 and A4, were incised. The fourth FDS ulnar hemi-tendon was harvested, passed through the A2 and A4 pulleys of the fifth finger, and sutured to the distal fifth FDP stump. To test finger flexion after tenorrhaphy, FDS and FDP tendons were pulled at wrist level, along the forearm axis, with a dynamometer. In all specimens, a complete flexion of fingers was obtained after FDS and combined FDS-FDP traction. The technique was applied in vivo for a staged reconstruction in a 35-year-old patient, resulting in good active and passive finger range of motion, a tip-to-palm distance of 0 mm, and no complications, bowstringing, or quadriga effect at 1-year follow-up. These cadaveric study and case report confirm that the fourth FDS ulnar hemi-tendon transfer is safe and effective in treating zone I fifth FDP delayed injuries, both during single and staged reconstructions.