Tenodesis for restoration of distal interphalangeal joint flexion in unrepairable flexor digitorum profundus injuries

Purpose To describe in a cadaveric model a tenodesis procedure for restoring distal interphalangeal joint flexion in patients with unrepairable isolated flexor digitorum profundus (FDP) injuries. Methods In 16 fresh-frozen cadaveric fingers, the FDP tendon was transected 1 cm proximal to its insertion to simulate an isolated zone I laceration. The injury was reconstructed using a palmaris longus tendon graft to create a mechanical linkage between the interphalangeal joints, which restored coordinated interphalangeal joint flexion. Joint motion and the force required to flex and extend the fingers were tested before and after the tenodesis. Results After FDP zone I laceration, distal interphalangeal joint flexion with load applied to the flexor digitorum superficialis tendon averaged 2. The FDP flexion increased to a mean of 57 after the tenodesis. The sum of metacarpophalangeal, proximal interphalangeal and distal interphalangeal joint flexion averaged 186 before the tenodesis and increased to 233 after the tenodesis. The force required to achieve fingertip to palm contact and the force required to fully extend the proximal interphalangeal joint were not altered. Conclusions In this cadaveric model, this tenodesis successfully restored coordinated interphalangeal joint flexion after a simulated zone I FDP laceration with improvements in distal interphalangeal joint flexion and composite finger flexion. Critical factors such as the effects of inflammation, edema, soft tissue healing, and scar formation could not be evaluated and would likely affect the outcomes of this procedure. The in vivo results of this procedure are not known. Clinical relevance The potential use of this tenodesis for treating unrepairable isolated zone I FDP injuries was demonstrated in a cadaveric model. Further investigation of the outcomes and complications in vivo would be required before routine clinical use.