A BIOMECHANICAL STUDY OF THE FLEXOR DIGITORUM SUPERFICIALIS - EFFECTSOF DIGITAL PULLEY EXCISION AND LOSS OF THE FLEXOR DIGITORUM PROFUNDUS

Many reports have been devoted to characterizing the significance of t he pulleys for the flexor digitorum profundus (FDP). However, no compa rable work has been published on the flexor digitorum superficialis (F DS). This study characterized the FDS in a human cadaver model. Eleven fresh-frozen cadaver hands were used. By using a tensiometer, data we re gathered for tendon excursion, tendon load, and work of flexion. Ch anges in efficiency were caused by excision of annular pulleys A1, A2, A3, and the palmar aponeurotic pulley. We also measured the effect of FDP excision on FDS efficiency. Sectioning of the A2 and A3 pulleys t ogether caused statistically significant losses of efficiency in all t hree parameters (work, load, and excursion). When the FDP was removed from a finger with an intact pulley system, losses in both work and ex cursion efficiencies were significant. Removing the FDP while cutting different pulleys caused significant decrease in FDS excursion efficie ncy. We conclude that A2 and A3 are the most important pulleys for mai ntaining normal FDS function, and that the presence of the FDP in the digital sheath is essential for optimal FDS excursion efficiency.