Hip abduction angles and foot placement, not lateral trunk flexion influence trunk orientation. Anticipation influences hip and knee neuromuscular control and therefore may guide the development of ACL prevention strategies.

Study Design: Two-factor mixed-design study, with factors including group (control and noncoper) and task (sidestep, crossover, and straight). Objectives: To compare the knee and hip joint angles and moments of control subjects and subjects with an anterior cruciate ligament (ACL) deficient knee classified as noncopers, during a sidestep, crossover, and straight-ahead task. Background: Subjects with ACL deficiency primarily note difficulty with cutting tasks as opposed to straight-ahead tasks. Yet, previous studies have primarily focused on straight-ahead tasks. Methods and Measures: Fifteen subjects with ACL deficiency classified as noncopers, based on the number of giving-way episodes (Ͼ 1) and global question of knee function (Ͻ 60%), were included in this study. These subjects (10 male, 5 female; age range, 18-49 years) were compared to a healthy control group (7 male, 7 female; age range, 19-47 years). Position data collected at 60 Hz were combined with anthropometric and ground reaction force data collected at 420 Hz to estimate 3-dimensional knee and hip joint angles and moments. All subjects performed 3 tasks including a step and 45°sidestep cut, step and 45°crossover cut, and step and proceed straight. Two-way mixed-model ANOVAs were used to compare peak angle and moment variables between 10% to 30% of stance. Results: The ACL-deficient noncoper group had 1.8°to 5.7°less knee flexion angle compared to the control group across tasks (PϽ .043). The ACL-deficient noncoper group used 22% to 27% lower knee extensor moment during weight acceptance compared to the control group (PϽ .001). The sagittal plane hip extensor moments were 34% to 39% higher in the ACL-deficient noncoper group compared to the control group (PϽ .025). Hip frontal (PϽ .037) and transverse plane (PϽ .04) moments also distinguished the ACL-deficient noncoper from the control group. Conclusions: This study suggests that individuals who do not cope well after ACL injury rely on a hip control strategy during cutting tasks. J Orthop Sports Phys Ther 2005;35:531-540.

t MetHoDS anD MeaSuReS: The study included 16 subjects who are ACL deficient, classified as noncopers, and 20 healthy controls. Data were collected using an Optotrak Motion Analysis System and force plate integrated with Motion Monitor Software to generate knee joint angles, moments, and power. Each testing session included anticipated tasks, straight walking task (ST), and 45° side-step cutting tasks (SSC), followed by a set of unexpected straight walking (STU) and unexpected sidestep cutting (SSCU) tasks in a random order. For all tasks speed was maintained at 2 m/s. Peak knee angle, moment, and power variables during early stance were compared using 2-way mixed-effects ANOVA models.t ReSultS: For both the straight and sidestep tasks, the noncoper group did not show a dependence on whether the task was anticipated or unanticipated (group-by-condition interaction) for the knee angle (straight, P = .067; side-step cutting, P = .103), moment (straight, P = .079; side-step cutting, P = .996), and powers (straight, P = .181; side-step cutting, P = .183) during the loading response phase. However, during both straight and side-step cutting tasks, the subjects in the noncoper group used significantly lower knee flexion angles (straight, P = .002; side-step cutting, P = .019), knee moments (straight, P = .005; sidestep cutting, P,.001), and knee powers (straight, P = .013; side-step cutting, P,.001).t concluSionS: This study suggests subjects that are ACL deficient and classified as noncopers use a common abnormal movement pattern of lower knee extensor loading even during unanticipated tasks.

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