Modified flexor digitorum superficialis slip technique for A4 pulley reconstruction

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Hand Surgery

Background:

• Tendon injuries, particularly to the flexor digitorum profundus (FDP), can lead to significant functional deficits.
• A4 pulley insufficiency can cause bowstringing of the FDP tendon, impairing finger flexion and strength.
• Current reconstruction techniques may have limitations in accommodating FDP repairs of increased bulk.

Purpose of the Study:

• To describe a modified A4 pulley reconstruction technique utilizing a single slip of the flexor digitorum superficialis (FDS) insertion.
• To biomechanically evaluate the efficacy of this novel reconstruction in reducing FDP tendon bowstringing and assessing repair integrity.

Main Methods:

• A variation of the A4 pulley reconstruction was performed in cadavers, transferring one FDS slip over the FDP tendon.
• The transferred FDS slip was sutured to the contralateral FDS insertion, creating an adjustable pulley.
• Biomechanical testing assessed the reduction in tendon excursion (bowstringing) and the repair's resistance to a proximally directed force.

Main Results:

• The described A4 pulley reconstruction resulted in a 57% reduction in excess FDP tendon excursion compared to no repair.
• The modified pulley repairs demonstrated high mechanical strength, with 94% maintaining integrity under a 50 N force.

Conclusions:

• This FDS slip-based A4 pulley reconstruction technique effectively addresses FDP tendon bowstringing.
• The method offers a robust and adjustable solution for A4 pulley reconstruction, particularly beneficial for FDP repairs with increased bulk.