• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.385-390
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• 2014

The purpose of this study was to investigate the effects of landing tasks on the anterior cruciate ligament (ACL) injury risk factors in female basketball players. Fifteen female basketball players performed a drop landing and a drop landing with a vertical jump on the 40 cm height box. Three-dimensional motion analysis system and ground reaction force system was used for calculate the ACL injury risk factors. Paired samples t-test with Bonfferoni correction were performed. The drop landing with a vertical jump had the higher knee flexion angle, peak knee varus moment, trunk flexion angle than a drop landing. However, the drop landing had the higher trunk rotation angle than a drop landing with a vertical jump. These results indicate that seemingly minor variations between drop landing and drop landing with a vertical jump may influence the ACL injury risk factors. Caution should be used when comparing studies using different landing tasks.

• Physical Therapy Korea
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• v.16 no.4
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• pp.1-7
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• 2009

The active-knee-extension (AKE) test has been used to measure hamstring muscle length. The traditional AKE test measures the popliteal angle to the point of resistance with a 90-degree flexion of the hip fixed by straps, while the stabilized AKE test measures the popliteal angle to the point of resistance with a 90-degree flexion of the hip stabilized using a pressure biofeedback unit providing lumbopelvic stabilization. The purpose of this study was to determine test-retest reliability of the traditional AKE test and stabilized AKE test. Twenty healthy adults participated in the study. The popliteal angles were measured with a digital inclinometer during each test. To assess the test-retest reliability between the 2 test sessions, intraclass correlation coefficients (ICCs) were calculated. The intrasubject coefficient of variation ($CV_{intra}$) was also calculated. To compare the traditional and stabilized AKE tests for changes in pressure, paired t-tests were applied. The results of this study were as follows: 1) ICCs(3,1) value for test-retest reliability was .96 in the traditional AKE test, and was .98 in the stabilized AKE test. 2) The maximal $CV_{intra}$ was 33.7% in the traditional AKE test and 15.7% in the stabilized AKE test. 3) Differences of $6.1{\pm}2.1$ mmHg in pressure were measured in the traditional AKE test, and differences of $1.2{\pm}1.0$ mmHg in pressure were measured in the stabilized AKE test. The results show the traditional and stabilized AKE test to be highly reliable, with test-retest reliability. However, the stabilized AKE test represented less variation and more stabilization than the traditional AKE test. Further study is needed to measure the inter-rater reliability of the stabilized AKE test for generalization and clinical application.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.100-104
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• 2011

The purpose of this article is to examine correlation between femoral rotational angle and subjective satisfaction of high tibial osteotomy outcome of the range of motion of knee joint. The subjects were 15 patients (6 males, 9 females) with primary osteoarthritis undergoing high tibial osteotomy from June of 2004 to August of 2008. They were CT tested on the knee joint before and after high tibial osteotomy. TEA (Fig. 1) and Akagi's line (Fig. 2) are analyzed as percentages. The Kendall's and Spearman's nonparametric correlation coefficient were used for the statistical tests with 0.5 level of significance. The result reveals that femoral rotational angle correlates with not the range of motion of knee joint but subjective satisfaction of the patients. Therefore, this will enable patients and physicians to have better clinical outcome.

• Journal of Korean Foot and Ankle Society
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• v.20 no.4
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• pp.145-151
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• 2016

Purpose: To evaluate the reliability of preoperative and postoperative distal metatarsal articular angle (DMAA) measurements and to determine whether such reliability is different in accordance with the foot and ankle fellowship and the number of years in practice. Materials and Methods: Between July 2012 and June 2014, a total of 20 patients (24 feet) were treated with proximal chevron osteotomy and distal soft tissue procedure for symptomatic hallux valgus deformity. DMAA were measured twice with an interval of two weeks between the preoperative and postoperative dorsoplantar radiographs by four observers; two of whom were foot and ankle surgeons (A and B), one knee surgeon, and one senior resident. The intraobserver reproducibility and interobserver reliability were assessed by intraclass correlation coefficients. Moreover, the limit of agreement between the preoperative and postoperative DMAA measurements were assessed using a Bland-Altman plot. Results: The intraobserver reproducibility of the foot and ankle surgeon A, knee surgeon, and senior resident improved from 0.796, 0.575, and 0.586 preoperatively to 0.968, 0.864, and 0.864 postoperatively, respectively. The interobserver reliability of foot and ankle surgeon A-B, foot and ankle surgeon A-knee surgeon, and foot and ankle surgeon A-senior resident improved from 0.874, 0.688, and 0.677 preoperatively to 0.971, 0.917, and 0.838 postoperatively, respectively. Conclusion: The intra- and interobserver reliabilities for DMAA measurement improved after proximal chevron osteotomy. Therefore, the necessity of additional procedures to correct the increased DMAA should be reevaluated after proximal chevron osteotomy in the hallux valgus with an increased DMAA.

• Physical Therapy Korea
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• v.12 no.2
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• pp.11-19
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• 2005

Patellofemoral pain syndrome (PFPS) is often attributed to malalignment and maltracking of patella within the patellofemoral joint. Most exercise for PFPS has focused on selectively strengthening the vastus medialis oblique muscle (VMO). This study was designed to identify the effect of medial, lateral wedge and difference of Quadriceps angle (Q-angle) on vastus medialis oblique/vastus lateralis muscle (VL) activity ratios. The subjects were twenty young adult males who had not experienced any knee injury. They were asked to perform isometric contraction exercises in three postures using medial and lateral wedge. The EMG activity of the VL and VMO were recorded in three postures by surface electrodes and normalized by %MVC values derived from seated, isometric knee extensions. The normalized EMG activity levels (%MVC) of the VL and VMO for the three postures of the lower extremities were compared using 2-way repeated measures ANOVA with 1 between-subject factor (group), and 1 within-subject factor (wedge). Results of repeated measures of ANOVA's revealed that the medial wedge isometric contraction exercise produced significantly greater EMG activity of VMO/VL ratios in Group I (Q-angle $18^{\circ}$ or less) (p<.05). But, the medial wedge isometric contraction exercise was no significant difference of VMO/VL ratios in Group II (Q-angle $19^{\circ}$ or more) (p>.05). These results have important implications for selective VMO muscle strengthening exercises in PFPS patients.

• Journal of the Korean Society of Safety
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• v.23 no.1
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• pp.35-45
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• 2008

This study was performed to compare the kinematics among three different safety shoes(type 1: ergonomically designed and high quality shoes, 2: curved and cushioned safety shoes, and 3: regular safety shoes) and to find the effect of insole during walking. Ten healthy subjects were recruited for this study. The range of motion of knee and ankle joint, angle of rear foot and angle of heel contact were measured using a three dimensional motion analysis system. In the second peak, the angle of heel contact showed statistically significant difference between safety shoes and insole, however, there was no statistical significance among three different safety shoes. The angle of ankle increased significantly at initial contact, first peak, the second peak and the toe off phase compared with type 1 and 2 safety shoes, and the angle of ankle showed statistically significant difference between with and without applying the insole. During the first peak, the second peak and the toe off phase, the angle of knee was statistical significance between safety shoes and insole. In heel contact, the angles of Achilles' tendon showed statistically significant difference between safety shoes and insole. The rear foot angles showed statistically significant difference between safety shoes and insole during heel contact and early heel contact. These results suggest that the type 1 safety shoes were superior to others in the statistics, and applying insole could be a possible method to prevent fatigue of lower extremity and musculoskeletal disorders. Further studies are needed to find the effect of ergonomically designed safety shoes and insole on practical value in prevention of musculoskeletal disorder, fatigue and satisfaction of workers.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.83-94
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• 2012

The purpose of this study was to analyse the effect of posture correction & stabilization according to horse rider's(n=10) skill levels of novice(0wk), mid-skill(12wk) & skill(24wk) in walk & trot. First, Mean posture of 3 times experiments; Anterior & posterior leaning posture of trunk showed rather unstable according to progress of the stages of TD1, TO, TD2 phase, and also shoulder & elbow angle, which effects to the distance from bit to rein, showed unstable riding posture. There was close relationship between shoulder and elbow Angle in walk and hip, knee & ankle angle in trot. Second, Posture correction & stabilization according to riding skill levels; Anterior & posterior leaning posture of trunk did not show significant difference statistically but showed approaching tendency to trunk's vertical line and showed significant difference(p<.05) according to improvement of skill levels in walk & trot horse riding. Hip angle showed significant difference according to progress of the stages of TD1, TO, TD2 phase(p<.05) and showed tendency maintaining the larger thigh flexion according to improvement of skill levels in walk & trot. Knee angle showed more stable posture by maintaining the larger flexion between thigh and shank according to improvement of skill levels in walk & trot(p<.05). Ankle angle also showed tendency maintaining the larger plantar flexion of foot according to improvement of skill levels in walk & trot. When considering the above, regular horse riding program could be useful in posture correction & stabilization according to improvement of skill levels of novice(0wk), mid-skill(12wk) & skill(24wk) in walk & trot.

• Journal of radiological science and technology
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• v.43 no.3
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• pp.161-167
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• 2020

This study aimed to found out the effect of patellofemoral overlap distance by changing femur thickness and center X-ray angles in Merchant method images. Based on the femur thickness, it suggested tube angle minimizes overlap. It was conducted by Merchant method, a knee tangential view, and the image was obtained by changing the thigh thickness from 14 to 20 cm and the center ray angle from 60°, 57°, 55°. The images were measured by five researchers using a method of measuring the overlap, which was designed by them. The results showed at 60°, 57°, 55° angle, the patellofemoral overlap distance resulted in 0.47±0.66 to 20.89±0.65 cm, 2.26±0.28 to 15.73±0.62 cm, 1.39 ± 0.83 to 12.49 ± 0.37 cm. However, for 57° and 55°, no overlap in thickness under 14.5 and 14 to 15.5 didn't appear. it showed high correlation between femur thickness and overlap. The difference in the mean value of overlap in each group showed a statistically significant difference (p<0.01), all were classified as independent groups in the post-hoc test. In all images, the patellofemoral overlap distance increased as the thickness increased, and at the average thickness of Korean men and women, overlap decreased when reducing center ray. When conducting Merchant tests on Koreans, it was suggested it would be useful to use 57° angle because it minimize the effects of overlap and intrusions of tibia.

• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.75-87
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• 2003

The purpose of this study was to identify the mechanical factors that are crucial to the successful double salto backward piked dismount on the parallel bars. The subjects were 5 national gymnasts(G1: sucessed landing, G2: failed landing), two video cameras were used to record the dismount of the subjects. It summarizes that (a) It is important to make small slope angle(X axis, Y axis) at release, whereas it makes large shoulder angle and trunk rotation angle. (b) It is important to prepare landing in advance, reducing vertical velocity and making large hip angle at BTO(body take off). (c) It is also important to make small knee angle and hip angle, and reduce the angle of trunk rotation.

• The Journal of Korean Physical Therapy
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• v.23 no.5
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• pp.49-56
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• 2011

Purpose: The purpose of this study was to investigate the kinematic characteristics and muscle activities during the following two conditions: transition from half-kneel to standing on the affected leg and non-affected leg. Methods: Twenty-one hemiplegic patients participated in the study. A motion analysis system was used to record the range of motion and angle velocity of the hip, knee and ankle from the half-kneel to the standing position. Electromyography was used to record the activity of 4 muscles. Results: The statistical analysis showed that the minimum ROM of the hip joint was less on the affected leg during transition from half-kneel to standing. However, the minimum ROM of the knee and ankle joints was less on the non-affected leg during transition from half-kneel to standing. The angle velocity of the knee and ankle joints was less during transition from half kneeling to standing on the non-affected leg. Muscle activity of the rectus femoris and tibialis anterior was less while moving from half-kneel to the standing position on the affected leg. Conclusion: These results show that greater active ROM of the knee and ankle was required on the affected leg for transition from half-kneel to the standing position than for normal gait. Muscle activity of the rectus femoris and tibialis anterior is normally required for movement from the half-kneel to the standing position during normal gait. Further studies are needed to investigate the antigravity movement in healthy subjects and hemiplegic patients in order to completely understand the normal and abnormal movement from the half-kneel to the standing position.