Differential splintage for flexor tendon rehabilitation: an experimental study of its effect on finger flexion strength.

We conducted laboratory tests to investigate the possibility of partly de-powering flexor digitorum profundus with a view of reducing flexion force during active flexor tendon rehabilitation. We constructed a splint and applied tapes to the proximal segments of fingers to test the hypothesis that holding three fingers more extended than the other finger would reduce the flexion strength of the more flexed finger. The splint allowed the metacarpophalangeal joint of the more flexed finger to be held in three positions of increasing flexion (15 degrees , 30 degrees , and 45 degrees ) compared to the remaining three fingers. We have called this 'differential splintage'. Healthy volunteers were tested for maximum active flexion strength at the different flexion angles. 'Differential splintage' of up to 45 degrees resulted in mean decreased flexion strength of 28% in the index finger and 35% to 38% in the middle, ring and little fingers. The results suggest that "differential splintage" of a finger after flexor tendon repair may be useful in reducing tension across the repair during a program of active tendon rehabilitation and we feel that it has potential to reduce the incidence of repair rupture before healing is complete.