Visual Biofeedback and Changes in Lower Extremity Kinematics in Individuals With Medial Knee Displacement

Abstract

Context Increased frontal-plane knee motion during functional tasks, or medial knee displacement, is a predictor of noncontact anterior cruciate ligament injury and patellofemoral pain. Intervention studies that resulted in a reduced risk of knee injury included some form of feedback to address aberrant lower extremity movement patterns. Research on integrating feedback into single-legged tasks and the ability to train 1 task and test another is limited. Objective To determine if adding real-time visual biofeedback to common lower extremity exercises would improve single-legged landing mechanics in females with medial knee displacement. Design Cohort study. Setting University laboratory. Patients or Other Participants Twenty-four recreationally active females with medial knee displacement were randomized to a visual-biofeedback group (n = 12; age = 19.75 ± 0.87 years, height = 165.32 ± 8.69 cm, mass = 62.41 ± 8.91 kg) or a control group (n = 12; age = 19.75 ± 0.97 years, height = 166.98 ± 6.89 cm, mass = 59.98 ± 6.24 kg). Intervention(s) Individuals in the feedback group viewed a real-time digital model of their body segments generated by Microsoft Kinect. The skeletal model changed color according to the knee-abduction angle of the test limb during the exercise tasks. Main Outcome Measure(s) Participants completed 3 trials of the single-legged drop vertical jump (SL-DVJ) while triplanar kinematics at the trunk, hip, knee, and ankle were collected via 3-dimensional motion capture. The feedback and control groups completed lower extremity exercises with or without real-time visual biofeedback, respectively. After the intervention, participants completed 3 additional trials of the SL-DVJ. Results At baseline, the feedback group had 3.83° more ankle eversion than the control group after initial contact. After the intervention, the feedback group exhibited 13.03° more knee flexion during the flight phase of the SL-DVJ and 6.16° less knee abduction after initial contact than the control group. The feedback group also demonstrated a 3.02° decrease in peak knee-abduction excursion compared with the baseline values (P = .008). Conclusions Real-time visual biofeedback immediately improved faulty lower extremity kinematics related to knee-injury risk. Individuals with medial knee displacement adjusted their movement patterns after a single training session and reduced their medial knee motion during a dynamic task.

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