Knee joint kinematics and kinetics during a lateral false-step maneuver.

CONTEXT: Cutting maneuvers have been implicated as a mechanism of noncontact anterior cruciate ligament (ACL) injuries in collegiate female basketball players.

OBJECTIVE: To investigate knee kinematics and kinetics during running when the width of a single step, relative to the path of travel, was manipulated, a lateral false-step maneuver.

DESIGN: Crossover design.

SETTING: University biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS: Thirteen female collegiate basketball athletes (age = 19.7 +/- 1.1 years, height = 172.3 +/- 8.3 cm, mass = 71.8 +/- 8.7 kg).

INTERVENTION(S): Three conditions: normal straight-ahead running, lateral false step of width 20% of body height, and lateral false step of width 35% of body height.

MAIN OUTCOME MEASURE(S): Peak angles and internal moments for knee flexion, extension, abduction, adduction, internal rotation, and external rotation.

RESULTS: Differences were noted among conditions in peak knee angles (flexion [P < .01], extension [P = .02], abduction [P < .01], and internal rotation [P < .01]) and peak internal knee moments (abduction [P < .01], adduction [P < .01], and internal rotation [P = .03]). The lateral false step of width 35% of body height was associated with larger peak flexion, abduction, and internal rotation angles and larger peak abduction, adduction, and internal rotation moments than normal running. Peak flexion and internal rotation angles were also larger for the lateral false step of width 20% of body height than for normal running, whereas peak extension angle was smaller. Peak internal rotation angle increased progressively with increasing step width.

CONCLUSIONS: Performing a lateral false-step maneuver resulted in changes in knee kinematics and kinetics compared with normal running. The differences observed for lateral false steps were consistent with proposed mechanisms of ACL loading, suggesting that lateral false steps represent a hitherto neglected mechanism of noncontact ACL injury.