Giving way event during a combined stepping and crossover cutting task in an individual with anterior cruciate ligament deficiency

Study Design: Case study. Objective: To compare knee kinematics and moments of nongiving way trials t o a giving way trial during a combined stepping and crossover cutting activ ity. Background: The knee kinematics and moments associated with giving way epis odes suggest motor control strategies that lead to instability and recovery of stability during movement. Methods and Measures: A 27-year-old woman with anterior cruciate ligament d eficiency reported giving way while performing a combined stepping and cros sover cutting activity. A motion analysis system recorded motion of the pel vis, femur, tibia, and foot using 3 infrared emitting diodes placed on each segment at 60 Hz. Force plate recordings at 300 Hz were combined with limb inertial properties and position data to estimate net knee joint moments. The stance time, foot progression angle, and cutting angle were also includ ed to evaluate performance between trials. Results: Knee internal rotation during the giving way trial increased 3.2 d egrees at 54% of stance relative to the nongiving way trials. Knee flexion during the giving way trial increased to 33.1 degrees at 66% of stance, and the knee moment switched from a nominal flexor moment to a knee extensor m oment at 64% of stance. The knee abductor moment and external rotation mome nt during the giving way trial deviated in early stance. Conclusions: The observed response to the giving way event suggests that in creasing knee flexion may enhance knee stability for this subject. The tran sverse and frontal plane moments appear important in contributing to the gi ving way event. Further research that assists clinicians in understanding h ow interventions can impact control of movements in these planes is necessa ry.