• Physical Therapy Korea
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• v.21 no.3
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• pp.1-10
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• 2014

The aim of this study was to investigate the effect of hip external rotation angle on pelvis and lower limb muscle activity during prone hip extension. Sixteen healthy men were recruited for this study. Each subject performed an abdominal drawing-in maneuver (ADIM) in a prone position, and extended the dominant hip at three different hip external rotation angles ($0^{\circ}$, $20^{\circ}$, $40^{\circ}$) with a $30^{\circ}$ hip joint abduction. Activity of the gluteus maximus (G Max), gluteus medius (G Med), and hamstring (HAM) and the G Max/HAM and G Med/HAM ratios were determined with surface electromyography (EMG). The EMG signal was normalized to 100% maximum voluntary isometric contractions (MVICs) and expressed as %MVIC. Data were analyzed by one-way repeated analysis of variance (alpha level=.05) and the Bonferroni post hoc test. Significant differences in G Max and G Med muscle activity were noted among the three different hip external rotation angles. G Max muscle activity increased significantly at both $40^{\circ}$ (p=.006) and $20^{\circ}$ (p=.010) compared to a $0^{\circ}$ hip external rotation angle. G Med muscle activity increased significantly at $20^{\circ}$ (p=.013) compared to a $40^{\circ}$ hip external rotation angle. The G Max/HAM activity ratio increased significantly at both $40^{\circ}$ (p=.004) and $20^{\circ}$ (p=.014) compared to a $0^{\circ}$ hip external rotation angle. The G Med/HAM activity ratio increased significantly at $20^{\circ}$ (p=.013) compared to a $40^{\circ}$ hip external rotation angle. In conclusion, $40^{\circ}$ and $20^{\circ}$ hip external rotation angles are recommended to increase G Max activity, and $20^{\circ}$ hip external rotation is advocated to enhance G Med muscle activity during prone hip extension with ADIM and $30^{\circ}$ hip abduction in healthy subjects.

• Physical Therapy Korea
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• v.18 no.1
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• pp.57-63
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• 2011

The purpose of this study was to identify the effects of manual facilitation and a stick on lumbar and hip joint flexion angles in subject with lumbar flexion syndrome during forward bending from a sitting position. Fifteen subjects with lumbar flexion syndrome were recruited for this study. As a pretest, all subjects performed three repetitions of bending the trunk forward until the tips of their fingers touched the target bar. After this pretest, the subjects practiced the forward bending of the trunk 10 times, using either manual facilitation or a stick. Then, as a posttest, all subjects repeated the pretest procedure. The flexion angles of lumbar spine and hip joint during forward bending in a sitting position were measured using a three-dimensional motion analysis system. A paired t-test was used to determine the statistical differences between pre-test and post-test flexion angles and pre- and post-test flexion angle differences between forward bending with manual facilitation and forward bending with a stick. The level of statistical significance was set at p=.05. The results of the study showed that the angle of the lumbar flexion decreased significantly and the bilateral hip flexion angle increased significantly when performing forward bending with stick and manual facilitation. Furthermore, the angle of lumbar flexion decreased significantly and the angle of bilateral hip flexion increased significantly in forward bending with a stick compared to forward bending with manual facilitation. The findings of this study indicate that both forward bending with manual facilitation and sticks could be used to prevent excessive lumbar flexion and increase hip flexion, and that forward bending with a stick is more effective than forward bending with manual facilitation for inducing lumbar spine and hip joint angle changes.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.119.3-119
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• 2002

$\textbullet$ A bone-mountable surgical robot system for hip surgery $\textbullet$ A simple gauge-based registration method $\textbullet$ A proposed surgical procedure $\textbullet$ Evaluation method for position/orientation accuracy $\textbullet$ Evaluation method for surface conformity $\textbullet$ The performance evaluation of ARTHROBOT $\textbullet$ Summary

• Journal of radiological science and technology
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• v.22 no.1
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• pp.21-26
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• 1999

To make a comparative analysis for clinical application of total hip replacement arthroplasty(THRA) using fluoroscopy, we have performed total hip replacement arthroplasty making 30 patients an object with general radiography and fluoroscopy respectively. The results are as follows : 1) Reexamination rate was 80% of patients and mean 3.9 sheets in the general radiography, where as it was 46.7% and 0.37 sheets in the fluoroscopy(p<0.01) 2) Add examination was 2 cases in the general radiography, but fluoroscopy was no add examination. 3) The total film sheet used was mean 10.16 in the general radiography and 6.73 in the fluoroscopy. 4) In the cause of reexmination and add examination, inaccurate position of patient accounted for 72.6% in the general radiography and poor exposure condition accounted for 45.5% in the fluoroscopy. Total hip replacement arthroplasty using the fluoroscopy decreased reexamination and add examination rate, for these reasons, this method was effective abatement of pain, exposured radiation dose, and examination time and so on.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.768-778
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• 1998

Human beings usually absorb a shock from terrain during walking through the damping effects of joints, muscles and skin. With this analogy, a robot-leg with a shock absorber is built to absorb the impact forces at its foot during high-speed walking on irregular terrain. To control the hip position while walking, the dynamic controller suitable for high speed walking is designed and implemented based on a dynamic model by Kane's equation. The hip position tracking performances of various controllers (PID controller, computed torque controller and feedforward torque controller) are compared through the experiments of the real robot-leg.

• The Journal of Korean Physical Therapy
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• v.21 no.1
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• pp.57-63
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• 2009

Purpose: We determined the recruitment pattern of lumbar elector spinalis, gluteus maxims, inner and outer hamstring muscle during trunk flexion and extension. Methods: Thirty healthy subjects(male; 15, female; 15) without low back pain and other problems in lower extremities participated in this study. To measure the recruitment pattern, the onset times of electromyographic activity of the muscles were recorded during trunk flexion and return(extension) to standing position. Results: The medial and lateral hamstring muscle was activated first, next elector spinalis, the last, gluteus maximus in trunk flexion. In trunk extension to standing position, the order of recruitment was similar to trunk flexion although the frequency is different. There were different between male and female in flexion and extension movement. Conclusion: The recruitment order of lumbar extensor and hip extensors in trunk flexion and extension will provide database in evaluation and intervention of lower back pain and lumbo.pelvic rhythm disorder.

• Physical Therapy Korea
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• v.18 no.3
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• pp.26-37
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• 2011

Although there have been various studies related to the body's movement from a sitting to a standing position (sit-to-stand task), there is limited information on the kinematic changes on the frontal and transverse planes. The purpose of this study was to ascertain how pelvic tilt affects kinematic changes in the frontal and transverse planes in the hip and knee joints during a sit-to-stand task. For this study, 33 healthy participants (13 female) were recruited. Each participant rose from a sitting to a standing posture at his or her preferred speed for each of three different pelvic tilt trials (anterior, posterior, and neutral), and the measured angles were analyzed using a 3-D motion analysis system. A one-way repeated measure analysis of variance was performed with Bonferroni's post hoc test. In addition, an independent t-test was carried out to determine the sex differences in hip and knee joint kinematic changes during the sit-to-stand tasks. The results were as follows: 1) The hip and knee joint angle in the frontal and transverse planes showed a significant difference between the different pelvic tilt postures during sitting in the pre-buttock lift-off phase (pre-LO) (p<.05). Compared to the posterior pelvic tilt posture, the anterior pelvic tilt posture involved significantly greater hip joint adduction and internal rotation, knee joint adduction, and reduced internal rotation of the knee joint. 2) Sex differences were found with significant differences for males in the initial and maximal angles in the frontal plane of the hip and knee joint (p<.05). Females had a significantly smaller initial abduction angle of the hip joint and a significantly greater maximal angle of the hip adduction joint. These results suggest that selecting a sit-to-stand exercise for pelvic tilt posture should be considered to control abnormal movement in the lower extremities.

• Physical Therapy Korea
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• v.18 no.3
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• pp.1-7
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• 2011

The effects of an abdominal drawing-in maneuver (ADIM) using a pressure bio-feedback unit (PBFU) were compared to the effects of a pelvic belt (PB) on the muscle activities of the hip and back extensor muscles during hip extension in the prone position. Fifteen healthy male participants all performed prone hip extensions under three conditions: 1) preferred hip extension (PHE), 2) performing an ADIM, and 3) using a PB. The muscle activities of the erector spinae, the gluteus maximus, and the medial hamstring on the right side were recorded by surface electromyography. The muscle activity of the erector spinae was significantly lower while performing an ADIM during prone hip extension than during PHE or with a PB (p<.05). Gluteus maximus muscle activity was significantly higher while performing an ADIM (p<.05). No significant difference was found for the medial hamstring muscle among the three conditions (p>.05). We concluded that the internal stabilization of the pelvis and lumbar spine afforded by the ADIM using a PBFU could be more effective than the external stabilization provided by a PB in terms of increasing selectively gluteus maximus activation during prone hip extension.

• Physical Therapy Korea
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• v.19 no.1
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• pp.19-27
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• 2012

The purpose of this study was to determine the effect of contralateral hip adduction (CHA) on thickness of lumbar stabilizers during hip abduction in side-lying. Twenty healthy subjects without back pain were recruited for this study. The thickness of transverse abdominis (TrA), internal oblique (IO) and quadratus lumborum (QL) were measured by ultrasonography. Pelvic lateral tilting motion was measured using a three-dimensional motion analysis system. Measurements were performed at rest position (RP), $35^{\circ}$preferred hip abduction (PHA) and $35^{\circ}$abduction with $10^{\circ}$contralateral hip adduction (CHA) in side-lying at the end of expiration. During the measurements, subjects were asked to maintain steady trunk alignment without hand support. Thickness of TrA and IO was significantly greater in CHA than in PHA and RP conditions. There was no significant difference in thickness of TrA and IO between PHA and RP conditions. Medio-lateral (M-L) thickness of QL was not significant between PHA and CHA conditions. Anterio-posterior (A-P) thickness of QL in PHA and CHA significantly decreased compared to RP condition. Angle of pelvic lateral tilting was significantly decreased in CHA compared to PHA condition. In conclusion, CHA can be recommended for increasing trunk stability without compensatory pelvic motion during hip abduction exercise in side-lying.

• Physical Therapy Korea
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• v.13 no.1
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• pp.24-31
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• 2006

The purpose of this study was to identify the effect of the hip internal rotation on gluteal and erector spinae muscle electromyographic (EMG) activity during treadmill walking. Eleven healthy subjects were recruited. All subjects performed treadmill walking while maintaining the hip in neutral position (condition 1) and in internal rotation (condition 2). Surface EMG activity was recorded from four muscles (gluteus maximus (GM), gluteus medius (GMED), tensor fascia latae (TFL), and erector spinae (ES)) and the hip internal rotation angle was measured using a three dimensional motion analysis system. The gait cycle was determined with two foot switches, and stance phase was normalized as 100% stance phase (SP) for each condition using the MatLab 7.0 program. The normalized EMG activities according to the hip rotation (neutral or internal rotation) were compared using a paired t-test. During the entire SP of treadmill walking, the EMG activities of GM in condition 1 were significantly greater than in condition 2 (p<.05). The EMG activities of TFL and ES in condition 2 were significantly greater than in condition 1 (p<.05). The EMG activities of the GMED in condition 1 were significantly greater than in condition 1 (p>.05) except for 80~100% SP. Further studies need randomized control trials regarding the effect of hip internal rotation on the hip and lumbar spine muscle activity. Kinetic variables during gait or going up and down stairs are also needed.