• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.143-149
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• 2018

Objective: This study aimed to investigate the influence of landing foot orientations on biomechanics of knee joint in order to identify vulnerable positions to non-contact knee injuries during single-legged landing. Method: Seventeen men (age: $20.5{\pm}1.1 years$, height: $175.2{\pm}6.4cm$, weight: $68.8{\pm}5.8kg$) performed single-leg drop landings repeatedly with three different landing foot orientations. They were defined as toe-in (TI) $30^{\circ}$ adduction, neutral (N, neutral), and toe-out (TO) $30^{\circ}$ abduction positions. Results: The downward phase time of TI was significantly shorter than those of N and TO. The flexion and valgus angle of N was greater than those of TI and TO at the moment of foot contact. At the instance of maximum knee flexion, N showed the largest flexion angle, and TO position had the largest varus and external rotation angles. Regarding ground reaction force (GRF) at the moment of foot contact, TO showed the forward GRF, while others showed the backward GRF. TI indicated significantly larger mediolateral GRF than others. As for the maximum knee joint force and joint moment, the main effect of different foot positions was not significant. Conclusion: TI and TO might be vulnerable positions to knee injuries because both conditions might induce combined loadings to knee joint. TI had the highest mediolateral GRF with a shortest foot contact time, and TO had induced a large external rotation angle during downward phase and the peak forward GRF at the moment of foot contact. Conclusively, N is the preferred landing foot orientation to prevent non-contact knee injuries.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.31-38
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• 2011

This study aimed to determine the effects of the blockage of visual feedback on joint dynamics of the lower extremity. Fifteen healthy male subjects(age: $24.1{\pm}2.3\;yr$, height: $178.7{\pm}5.2\;cm$, weight: $73.6{\pm}6.6\;kg$) participated in this study. Each subject performed single-legged landing from a 45 cm-platform with the eyes open or closed. During the landing performance, three-dimensional kinematics of the lower extremity and ground reaction force(GRF) were recorded using a 8 infrared camera motion analysis system (Vicon MX-F20, Oxford Metric Ltd, Oxford, UK) with a force platform(ORG-6, AMTI, Watertown, MA). The results showed that at 50 ms prior to foot contact and at the time of foot contact, ankle plantar-flexion angle was smaller(p<.05) but the knee joint valgus and the hip flexion angles were greater with the eyes closed as compared to with the eyes open(p<.05). An increase in anterior GRF was observed during single-legged landing with the eyes closed as compared to with the eyes open(p<.05). Time to peak GRF in the medial, vertical and posterior directions occurred significantly earlier when the eyes were closed as compared to when the eyes were open(p<.05). Landing with the eyes closed resulted in a higher peak vertical loading rate(p<.05). In addition, the shock-absorbing power decreased at the ankle joint(p<.05) but increased at the hip joints when landing with the eyes closed(p<.05). When the eyes were closed, landing could be characterized by a less plantarflexed ankle joint and more flexed hip joint, with a faster time to peak GRF. These results imply that subjects are able to adapt the control of landing to different feedback conditions. Therefore, we suggest that training programs be introduced to reduce these injury risk factors.

• Physical Therapy Rehabilitation Science
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• v.13 no.2
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• pp.240-249
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• 2024

Objective: The objective of this study is to evaluate various research that have examined dynamic knee valgus and to pinpoint a straightforward, clinically practical 2D assessment method for dynamic knee valgus that is user-friendly. Design: A literature review Methods: This literature review was conducted in Pubmed, MEDLINE^® and Google Scholar with the following key words: Knee valgus angle, Knee valgus evaluation, Knee valgus assessment, Dynamic knee valgus. After removing duplicate studies, 53 articles were initially chosen using this method, with 17 studies ultimately meeting the selection criteria. Results: Based on the comprehensive review of various studies, the Single Leg Squat (SLS) was identified as the most popular test method, followed by the Single Leg Landing (SLL) as the next most common test method. The Frontal Plane Projection Angle (FPPA) method was the most representative method for measuring dynamic knee valgus (DKV) during these tests. SLS was found in a total of 10 studies, while SLL was found in 7 studies. Conclusions: The most commonly proposed test for assessing DKV is measuring the SLS using the FPPA method. However, when applied to individuals without knee pathology, the discriminative power of this method may be limited. This suggests the need for further research to explore alternative methods for assessing DKV in this population.