Influence of the flexor digitorum superficialis tendon transfer on grip strength

The flexor digitorum superficialis tendon of the ring finger can be transferred to the thumb flexor. We followed ten patients after such a transfer for 5-128 months and measured grip strength and force transmission of the fingers and individual phalanges while the patients gripped 10-cm or 20-cm diameter cylinders. The grip strength of the middle, ring and little fingers was reduced when gripping the 10-cm cylinder, with a significantly larger decrease in the ring finger. With the 20-cm cylinder, grip forces of all fingers were almost identical, with slightly lower force of the ring finger and slightly higher forces in the index and small fingers. We conclude that after transfer of flexor digitorum superficialis tendon from a ring finger, grip strength of the ring finger is reduced. Finger forces are more hampered while gripping objects with smaller circumferences than large ones.