RESUMEN
Objective To discuss the effect of proximal interphalangeal joint(PIPJ) motion on the tension of the zone Ⅰ extensor tendon through measuring the extensor tendon and find the fixed position of PIPJ when the zone Ⅰ extensor tendon at minimum tension,and to provide reference for best fixed position in clinical treatment.Methods The maximal passive flexion angles of the distal interphalangeal joint (DIP J) of the index,distal,ring and little fingers were measured in 20 cadaver hands when the PIPJ flexed at 0 °,20 °,40 °,60 °,80 ° and 100 °.Making an incision over the back of the DIPJ to expose the zone Ⅰ extensor tendon.Incising the extensor tendon laterally at the level of the DIPJ with the DIPJ fixed in extension position to make a mallet finger.Pierced a Kirschner wire through and perpendicular to the distal phalangeal basement as a sign.Parallel to this sign,marked the zone Ⅰ extensor tendon and measured its relative distance to the sign as the sliding distance of the extensor.Recording the widest gap between the tendon edges and the tendon sliding distance while the PIPJ was in extension and 20°,40°,60°,80° and 100°flexion position,severally.Results The maximal passive flexion angle of the DIPJ increased with the PIPJ flexed from 0°to 100°in 80 fingers.The gap between the extensor tendon edges in zone Ⅰ was (1.322 8 ± 1.078 9) mm when the PIPJ was in extension position.The proximal extensor tendon glide distally while the PIPJ flexed to 100° with an average sliding distance of(1.540 5 ± 0.690 7) mm.Conclusion The zone Ⅰ extensor tendon has the maximal tension while the PIPJ is in extension position.Flexing PIPJ can make the tension decrease.