Immediate Effects of a Knee Brace With a Constraint to Knee Extension on Knee Kinematics and Ground Reaction Forces in a Stop-Jump Task

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Immediate Effects of a Knee Brace With a Constraint to Knee Extension on Knee Kinematics and Ground Reaction Forces in a Stop-Jump Task
First published on May 18, 2004
This version was published on July 1, 2004
Bing Yu, PhD*,, Daniel Herman, Jennifer Preston, MS, William Lu, PhD, Donald T. Kirkendall, PhD and William E. Garrett, PhD
The American Journal of Sports Medicine

© 2004 American Orthopaedic Society for Sports Medicine

From the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, and the University of Hong Kong, Hong Kong

* Address correspondence to Bing Yu, PhD, Division of Physical Therapy, CB# 7135 Medical School Wing E, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7135 (e-mail: byu@med.unc.edu).

Background: A small knee flexion angle in landing tasks was identified as a possible risk factor for noncontact anterior cruciate ligament injuries that are common in sports.

Hypothesis: A specially designed knee brace with a constraint to knee extension would significantly increase the knee flexion angle at the landing of athletic tasks preceded with horizontal movement components, such as stop-jump tasks.

Study Design: Repeated measure design for brace effects.

Methods: Three-dimensional videographic and force plate data were collected for 10 male and 10 female recreational athletes performing a stop-jump task with and without the specially designed brace. Knee flexion angle at landing, maximum knee flexion angle, and peak ground reaction forces during the stance phase of the stop-jump task were determined for each subject with and without the knee brace.

Results: The knee brace decreased the knee flexion angle at the landing by 5? for both genders but did not significantly affect the peak ground reaction forces during the landing.

Conclusions: The specially designed knee brace may be a useful device in the prevention and rehabilitation of noncontact anterior cruciate ligament injuries in sports.

Key Words: anterior cruciate ligament (ACL) Ô injury prevention Ô brace Ô landing Ô biomechanics

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