The A3 pulley.
The tendon-pulley geometry and gliding resistance with and without the A3 pulley were compared in 6 fresh human cadaver fingers. We measured the x-ray images of the distal A2 pulley-tendon angle and proximal A4 pulley-tendon angle with varying degrees of proximal interphalangeal joint flexion between 0 degrees and 120 degrees before and after A3 pulley resection. The gliding resistance of the flexor digitorum profundus tendon under the A2 pulley was also measured at varying tendon-pulley angles. With the A3 pulley removed, the tendon-pulley angle significantly increased compared with the A3 intact state. The gliding resistance between tendon and pulley quadratically increased as the tendon-pulley angle increase from 0 degrees to 60 degrees. These results indicate that the A3 pulley might serve to reduce tendon-pulley gliding resistance by reducing the tendon-pulley angle during finger flexion.
Zhao
C F
CF
Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic and Mayo Foundation, Rochester, MN 55905, USA.
Amadio
P C
PC
Berglund
L
L
An
K N
KN
D001696:Biomechanical Phenomena; D002102:Cadaver; D005240:Feasibility Studies; D006801:Humans; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D012399:Rotation; D013710:Tendons / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery