• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.245-248
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• 1997

Excessive stress on the bone-stem interface may cause local micromotion that could produce midthigh pain, interface bone resorption and prevent bony ingrowth. It is important for clinician and prosthetic designer to develop an understanding of the load transfer mechanism, its associated stress pattern and its relationships with the particular mechanical characteristics of the femoral stem designs. Finite element method (FEM) is preeminently suited to provide information in this respect. The authors developed 3-dimensional numerical finite element models implanted with the straight stem which is composed of total 1170 elements of 8 nodes and with the curved stem which is composed of total 885 elements of 8 node, and analysed the relative micromotions between the straight stem and the curved stem in immediate postoperative stage of an uncemented total hip replacement in load simulating the single leg stance. The results showed that the rotational displacement was occupied over 90% of total micromotion in both types of stem and was peak at the proximal medial portion of the stem, but markedly less distally. The curved stem was more stable especially in terms of rotational stability. It is recommended that surgeons do not allow the patient weight bearing until bony ingrowth was achieved. In the future more attention should be drawn to increase initial rotational stability of the two types of femoral stem to prevent loosening from excessive micromotion.

• 한국운동역학회지
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• 제30권1호
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• pp.73-81
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• 2020

Objective: The purpose of this study is to analyze the effects of aquatic walking exercise on gait and balance parameters of elderly women. Method: 15 elderly people were recruited for this study (age: 73.20±5.19 yrs, height: 153.87±3.36 cm, mass: 60.33±5.73 kg). All variables were measured using Gaitview AFA-50. The variables were the heel contact time ratio, gait angle, and M/P change ratio for gait patterns and ENV, REC, RMS, Total Length, TLC, Sway velocity, and Length/ENV for balance abilities. A paired t-test and the Wilcoxon signed-rank test were carried out to verify the differences in the test scores after participating in the water walking program. The significance level for all statistical analyses was set to α=.05. Results: As for the changes in their walking function after the exercise, heel contact time ratio (p<.01) showed a statistical significance, while gait angle and M/P change ratio did not reveal statistically significant differences. In the test of balance ability on both feet and with eyes opened, statistical significance was found in ENV, REC, RMS, TLC (p<.01), and sway velocity (p<.05), while the test with eyes closed showed statistical significance in length/ENV as well as ENV, REC, RMS, sway velocity (p<.01) TLC, and total length (p<.05). As for the single-leg stance balance ability, ENV and REC revealed statistically significant differences. Conclusion: These results show that water walking is effective for improving the function of the ankle flexor muscles, providing stability to the ankle joint during walking and helping efficient walk. In addition, it is also expected to help prevent falls due to loss of balance by improving the stability of lower extremity muscles and trunk.

• 성인간호학회지
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• 제16권3호
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• pp.409-420
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• 2004

Purpose: This study aims to analyze the effectiveness of Tai chi exercise for improving balance and its tendency and helps to identify directions for future research. Method: 19 articles from Medline search of foreign journals(1981-2003) and 5 from Korean nursing journals (1981-2003) were surveyed. The contents analyses were focused on outcome measures and relative factors regarding balance. Result: Variable measures for balance were used in Tai Chi studies relating to balance. They included the functional measures such as 14 single-leg stance, 7 walking in physiological measures and 7 laboratory-based balance measures were done with platform stability test. The measure of effective Tai Chi exercise depended on the health status of subjects and the methods. Health status of subjects were only on physically inactive older adults in 17 articles and arthritis patients in 7 articles in the Tai Chi study. The significant effects of Tai Chi exercise on balance was revealed after 10weeks duration. Conclusion: Considering the results, Tai Chi exercise is more effective than any other studies for walking balance. But the reports on the outcome are inconsistent with wide variations in the choice of balance measures. It is suggested that future studies analyze systemic change through meta analysis and have a wide variety of subjects who need postural control and balance control. The methods of measures should be distinct from the balance state of subjects for the effectiveness of Tai chi exercise.

• Safety and Health at Work
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• 제8권2호
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• pp.183-188
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• 2017

Background: Recommendations have been proposed for minimum aerobic fitness among firefighters but it is unclear if those criteria relate to performance on the fireground. Less fit individuals fatigue more quickly than fit individuals when working at comparable intensity and may have gait changes, increasing risk of falls. We evaluated the effect of fatigue during a live burn evolution on gait parameters and functional balance comparing them to aerobic fitness levels. Methods: A total of 24 firefighters had gait and balance tested before and after a live burn evolution. Data were stratified by aerobic fitness of greater/less than 14 metabolic equivalents (METs). Results: Analysis of gait cycles measurements before and after the live burn evolution revealed that single leg stance, cycle, and swing time decreased (p < 0.05) but there were no differences in the other measures. There were no differences in time to complete the functional balance test, or errors committed before or after a live burn evolution. When firefighters were sorted by fitness level of 14 METs, there were no differences for errors or time before or after the live burn evolution. Balance data were analyzed using a linear regression. Individuals with lower fitness levels required more time to complete the test. Conclusion: A 14-MET criterion failed to distinguish gait or balance characteristics in this group. However, less fit firefighters did require more time to complete the balance test (p = 0.003). Aerobic fitness alone does not predict gait changes among firefighters following a live burn evolution but does appear to influence functional balance.

• PNF and Movement
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• 제18권2호
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• pp.183-194
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• 2020

Purpose: Functional ankle instability (FAI) causes tension in the joints, ligaments, and tendons, and the impact on visual and vestibular organs leads to imbalance. This study compared the effects of a traditional balance training program to virtual reality training to improve FAI. Methods: Twenty-four participants with FAI (CAIT score < 24) were assigned to a virtual reality training group (n = 13) and a traditional balance training group (n = 11). Both groups pursued their respective training program for four weeks. After a ten-minute warm-up, participants completed a 30-minute training session, three times per week. The traditional balance training group underwent static and dynamic training using a balance board and a stability trainer pad while the virtual reality group underwent balance training using a virtual reality program. Biorescue was used to measure changes in the speed and length of center of pressure (COP) for single-leg stance pre- and post-training. Results: The speed and length of COP improved significantly in both groups after training as compared to before (p < 0.05). However, there were no significant differences in these outcomes between the virtual reality training group and the traditional balance training group (p>0.05). Conclusion: The study findings confirm the effectiveness of both virtual reality training and traditional balance training in reducing ankle instability, with no difference in treatment effects.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.61-70
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• 1996

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony inyowth and secondary long term fixation. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone stem interface. An accurate evaluation of interf'ace micromotion and stress/strain fields in the bone-implant system may be relevant for better understanding of clinical situations and improving THA design. Recently finite element method(FEM) was introduced in'orthopaedic research field due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional finite element model of proximal femur with $Multilock^{TM}$ stem of 1179 blick elements to analyse the micromotions and mechanical behaviors at the bone-stem inteface in early post-operative period for the load simulating single leg stance. The results indicates that the values of relative motion for this well fit stem were $150{\mu}m$ in maximum $82{\mu}m$ in minimum and the largest relative motion was developed in medial region of Proximal femur and in anterior-posterior direction. The motion in the proximal bone was much greater than in the distal bone and the stress pattern showed high stress concentration on the cortex near the tip of the stem. These findings indicate that the loading on the hip joint in the early postoperative situation before achieving bony ingrowth could produce large micromotion of $150{\mu}m$ and clinicaly non-cemented THA patient should not be allowed weight bearing strictly early in the postoperative period.

• 한국전문물리치료학회지
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• 제28권3호
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• pp.168-176
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• 2021

Background: The foot is a complex body structure that plays an important role in static and dynamic situations. Previous studies have reported that altered foot posture might affect knee joint strength and postural stability, however their relationship still remains unclear. Objects: The purpose of this study was to identify whether pronated foot posture has an influence on knee isokinetic strength and static and dynamic postural stability. Methods: Forty healthy young males aged 18 to 26 years were included. Foot posture was evaluated using the Foot Posture Index-6 (FPI-6), and the subjects were divided into two groups according to their FPI-6 scores: a neutral foot group (n = 20, FPI-6 score 0 to +5) and a pronated foot group (n = 20, FPI-6 score +6 or more). Biodex Systems 3 isokinetic dynamometer was used to evaluate knee isokinetic strength and hamstring to quadriceps ratio at three angular velocities: 60°/sec, 90°/sec, and 180°/sec. The static and dynamic postural stability in a single-leg stance under the eyes-open and eyes-closed conditions were measured with a Biodex Balance System. Results: There were no significant differences between the groups in knee isokinetic strength and static postural stability (p > 0.05), but there was a significant difference in the medial-lateral stability index (MLSI) for dynamic postural stability under the eyes-closed condition (p = 0.022). The FPI-6 scores correlated significantly only with the dynamic overall stability index (OSI) and the MLSI (OSI: R = 0.344, p = 0.030; MLSI: R = 0.409, p = 0.009) under the eyesclosed condition. Conclusion: Participants with pronated foot had poorer medial-lateral dynamic stability under an eyes-closed condition than those without, and FPI-6 scores were moderately positively correlated with dynamic OSI and dynamic MLSI under the eyes-closed condition. These results suggest that pronated foot posture could induce a change in postural stability, but not in knee isokinetic strength.