Modified flexor digitorum superficialis slip technique for a 4 pulley reconstruction

We describe a variation in the A4 pulley reconstruction technique using one slip of the flexor digitorum superficialis insertion and report the results of a biomechanical analysis of this reconstruction in cadavers. While conserving the distal bony insertion, one slip of flexor digitorum superficialis is transferred over the flexor digitorum profundus tendon and sutured to the contralateral superficialis slip insertion. This creates a new pulley at the base of the original A4 pulley that can be adjusted to accommodate an FDP repair of increased bulk. We found a 57% reduction in excess excursion due to bowstringing when compared with no repair. Furthermore the repairs were sturdy, 94% of specimens maintaining their integrity when a proximally directed force of 50 N was applied.