Abstract
The tibia axial rotation and knee joint valgus torque may increase anterior cruciate
ligament (ACL) tension in direction changes during daily activities. The purpose of
the study was to compare knee joint rotation and torque between step turn and spin
turn in direction change following walking downstairs. The knee joint axial rotation
and valgus torque were quantified from 20 healthy subjects. Significant differences
were found between 2 turn strategies and between 2 legs. Spin turn showed significantly
greater internal tibia rotation (13.5°±5.9°), greater tibia rotation range of motion
(−15.1°∼13.5°) than step turn (5.1°±5.2° and −11.5°∼5.1°) for both legs. Significantly
greater peak valgus torque during spin turn (−0.91±0.33 Nm/kg) was found than that
during step turn (−0.25±0.32 Nm/kg) for the left leg, while there was no significant
difference between 2 turn strategies for the right leg (spin turn: −0.44±0.23 Nm/kg,
and step turn: −0.40±0.27 N/kg). Excessive internal axial rotation combined with higher
valgus torque may make the ACL and ACL graft more vulnerable to injury. The study
indicated that, for right dominant people, turning with right leg or using step turn
might reduce the stress on the ACL or ACL graft after ACL reconstruction.
Key words
knee - valgus - axial rotation - spin turn - step turn
References
Correspondence
nzheng@uncc.edu
