The Effect of Flexor Digitorum Profundus Dynamic Tenodesis on the Distal Interphalangeal Joint: A Cadaver Study

Abstract

PurposeFlexor digitorum profundus (FDP) dynamic tenodesis on the distal interphalangeal (DIP) joint is reported as a treatment for FDP tendon injuries. Although good clinical outcomes have been reported, biomechanical study results are unknown. This study aimed to evaluate the flexion range of motion in DIP and proximal interphalangeal (PIP) joints that have undergone dynamic tenodesis using fresh-frozen cadavers.MethodsWe obtained 12 fingers from 3 fresh-frozen cadavers. Before and after the procedure, we assessed the relationships between the tension of the flexor tendons and the flexion angles of the DIP and PIP joints. We compared the maximum DIP and PIP joint angles using the Wilcoxon t test. The distal portion of the FDP was split longitudinally and the ulnar slip was resected from the insertion of the tendon. The remaining radial half of the FDP tendon was passed beneath both slips of the flexor digitorum superficialis tendon, which was then sutured to the radial insertion of the FDP tendon using a mattress stitch.ResultsMaximum flexion angles of the DIP joint before and after the procedure were 48° ± 12° and 34° ± 8°, respectively; this difference was statistically significant. Maximum flexion angles of the PIP joint before and after the procedure were 74° ± 14° and 80° ± 9°, respectively; this difference was not statistically significant.ConclusionsThe flexion angle of the DIP joint was reduced after undergoing dynamic tenodesis. Biomechanically, dynamic tenodesis for the DIP joint using the remaining FDP tendon is a valuable procedure because it results in a flexion angle greater than 30°.Clinical relevanceThe DIP joint can be flexed, and the PIP joint maintains good motion after the procedure. Therefore, FDP dynamic tenodesis on the DIP joint may be a choice in case of an isolated FDP tendon injury.