• Asian Spine Journal
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• v.12 no.6
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• pp.967-972
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• 2018

Study Design: Biomechanical study. Purpose: To investigate the relative stiffness of a new posterior pelvic fixation for unstable vertical fractures of the sacrum. Overview of Literature: The reported operative fixation techniques for vertical sacral fractures include iliosacral screw, sacral bar fixations, transiliac plating, and local plate osteosynthesis. Clinical as well as biomechanical studies have demonstrated that these conventional techniques are insufficient to stabilize the vertically unstable sacral fractures. Methods: To simulate a vertically unstable fractured sacrum, 12 synthetic pelvic models were prepared. In each model, a 5-mm gap was created through the left transforaminal zone (Denis zone II). The pubic symphysis was completely separated and then stabilized using a 3.5-mm reconstruction plate. Four each of the unstable pelvic models were then fixed with two iliosacral screws, a tension band plate, or a transiliac fixation plus one iliosacral screw. The left hemipelvis of these specimens was docked to a rigid base plate and loaded on an S1 endplate by using the Zwick Roell z010 material testing machine. Then, the vertical displacement and coronal tilt of the right hemipelves and the applied force were measured. Results: The transiliac fixation plus one iliosacral screw constructions could withstand a force at 5 mm of vertical displacement greater than the two iliosacral screw constructions (p=0.012) and the tension band plate constructions (p=0.003). The tension band plate constructions could withstand a force at $5^{\circ}$ of coronal tilt less than the two iliosacral screw constructions (p=0.027) and the transiliac fixation plus one iliosacral screw constructions (p=0.049). Conclusions: This study proposes the use of transiliac fixation in addition to an iliosacral screw to stabilize vertically unstable sacral fractures. Our biomechanical data demonstrated the superiority of adding transiliac fixation to withstand vertical displacement forces.

• The Journal of Korean Society for Neurotherapy
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• v.22 no.3
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• pp.19-23
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• 2018

Purpose The purpose of this study was to investigate the change of balance ability by performing closed chain exercise on stable support surface and unstable support surface in twenties. Methods This study randomly selected 15 students in the closed chain exercise group on the stable support side and 15 on the closed chain exercise group on the unstable support side. Balance ability was measured before and after the start of exercise and static balance was measured by OLT(One Leg Standing Test) and FRT (Functional Reach Test). Result The changes of the function reach test of the closed chain movement according to the ground type were significant in the unstable and stable support surfaces and the change of function reach test after the intervention in the two groups was significantly improved compared with the closed chain movement respectively. The one leg standing test changes of the closed chain movement according to the ground type showed significant results on the unstable and stable support surfaces, but there was no significant difference in the one leg standing test changes after intervention between the two groups. Conclusion The effect of closed chain training on ground type is unstable. The change of function reach test and one leg standing test of the closed chain exercise group on the stable support surface resulted in significant changes after exercise, but there was a significant difference in the balance ability of function reach test change after intervention between the groups.

• Journal of Korean Physical Therapy Science
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• v.25 no.3
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• pp.53-60
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• 2018

Purpose : The purpose of this study is to examine the Effect of Lunge Exercise on the Balance of Stable and Unstable Supporting surface. Method : The experimenter was a healthy twenties male and female. The period was two weeks, divided into a stable group and a unstable group. Setting the holding time 4 sec 3 sets of 10 times using the Stable and Unstable Supporting Surfaces. The break time was set at one minute for each set. Balance cushions were used for unstable supporting surfaces. Results : After Lunge Exercise, Both groups had an impact on improving their ability to balance. Conclusion : There has not been much change in the ability to balance the stable and Unstable Supporting Surfaces. However, considering surface conditions, the pre and post exercise comparisons had an effect on improving the ability to balance.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.211-223
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• 2021

Purpose : The purpose of this study was to examine the effect of task-oriented circuit training using unstable support surface on balance, gait ability, and balance confidence in subacute stroke patients. Methods : Forty-five patients with subacute stroke were randomly divided into the three following groups of 15: 1) TOCT-US group; task-oriented circuit training using unstable surface (experimental group 1), 2) TOCT-SS group; task-oriented circuit training using stable surface (experimental group 2), and 3) CON group; conventional physical therapy (control group). All patients participated in one of the three training programs for 6 weeks, 30 minutes per session, 3 times per week. Patients' balance ability was assessed using the BT-4, BBS (berg balance scale), TUG (time up and go test), and LOS (limit of stability). Gait speed was measured to examine gait ability. K-ABC (activities-specific balance confidence scale) was also used to assess the level of patients' confidence in daily activities. Results : After the intervention, the sway area in experimental groups 1 and 2 decreased, but that in the control group increased. Experimental group 1 showed significant improvement compared with experimental group 2 and the control group. BBS, TUG, and LOS scores of experimental group 1 were significantly improved compared with those of experimental group 2 and the control group. Also, gait speed significantly improved in experimental group 1 compared with experimental group 2 and the control group. Experimental groups 1 and 2 showed significant improvement in K-ABC scores after training. Conclusion : Patients with subacute stroke had significantly improved balance, gait, and level of confidence in performing activities of daily living following task-oriented circuit training using the unstable surface. This indicates that task-oriented circuit training using unstable surfaces can be an effective treatment method for the recovery of balance and gait in subacute stroke patients.

• The Journal of Korean Physical Therapy
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• v.33 no.6
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• pp.265-271
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• 2021

Purpose: We aimed to analyze the reliability of the test for choice stepping reaction time (CSRT) under an unstable surface and determine whether there were differences in CSRT between support surface conditions (stable vs. unstable conditions) and between age groups (young adults vs. community-dwelling older adults). Methods: Twenty healthy community-dwelling older adults and twenty young adults performed the stepping task under an unstable condition over two visits. The mean of the two trials measured for each visit was used for the analysis. The test-retest reliability was analyzed using intra-class correlation coefficient (ICC) with a 95% confidence interval, standard error of measurement (SEM), and minimal detectable change (MDC). Differences in CSRT between support surface conditions and age groups were analyzed using the independent t-test with Bonferroni correction. Results: Excellent consistency was observed for ICC >0.90 in both groups. Moreover, the SEM and MDC values of the CSRT in older and young adults were 0.03 and 0.09 and 0.01 and 0.04, respectively. There was a significant difference in the CSRT between the age groups under stable (p<0.001) and unstable conditions (p<0.001). Conclusion: The findings demonstrated that the test for CSRT under an unstable condition had reliable results in both groups. Although older adults demonstrated longer reaction times than younger adults in all surface conditions, increasing the balance control demand by implementing a choice stepping task concomitant with a balance task had no influence on the reaction time in both age groups.

• Journal of Biomedical Engineering Research
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• v.28 no.5
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• pp.590-600
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• 2007

We performed experimental studies on the muscle activities in the lower limbs for the different movement patterns on an unstable platform. A training system for postural control using an unstable platform that we previously developed was applied for the experiments. This unstable platform provides 360 degrees of movement allowing for training of posture in various directions and provides simultaneous excitations to visual sensory, somatic sensation and vestibular organs. Compare with the stable platform, keeping body balance on the unstable platform requests more effective sensation from vision, vestibular sense and somatic sense. Especially, the somatosensory inputs from the muscle proprioceptors and muscle force are crucial. To study the muscle activities for the different movement patterns and find the best training method for improving the ability of postural control through training and improving the lower extremity muscular strength, fifteen young healthy participants went through trainings and experiments. The participants were instructed to move the center of pressure following the appointed movement pattern while standing on the unstable platform. The electromyographies of the muscles in the lower limbs were recorded and analyzed in the time and the frequency domain. Our experimental results showed the significant differences in muscle activities for the different movement patterns. Especially, the spectral energy of electromyography signals in muscle for the movement pattern in anterior-posterior direction was significantly higher than those occurred in the other patterns. The muscles in the lower leg, especially tibialis anterior and gastrocnemius were more activated compared to the others for controlling the balance of body on the unstable platform. The experimental results suggest that, through the choice of different movement pattern, the training for lower extremity strength could be performed on specific muscles in different intensity. And, the ability of postural control could be improved by the training for lower extremity strength.

• Journal of Trauma and Injury
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• v.20 no.1
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• pp.26-32
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• 2007

Purpose: Hemorrhagic shock is the leading cause of death in patients with pelvic bone fractures. The majority of blood loss is due to injured pelvic arteries and retroperitoneal veins and to bleeding from the fracture site itself. Pelvic angiography and embolization of injured vessels is an effective way to control continuous bleeding. However, identifying the bleeding focus in hemodynamically unstable patients before diagnostic intervention is difficult. The purpose of this study was to determine the correlation between fracture patterns in hemodynamically unstable patients with pelvic fractures and later pelvic angiography findings. Methods: We performed a retrospective study of 21 hemodynamically unstable patients with pelvic fractures admitted to our emergency department between April 2001 to April 2006. All 21 patients underwent pelvic angiography. Pelvic fractures were assessed according to the Tile's classification and the degree of injury was assessed using the Injury Severity Score (ISS) and Revised Trauma Score (RTS). The hemodynamic status of the patients was defined using vital signs, base excess, and blood lactate. Fracture patterns were compared with hemodynamic status and angiography findings. Results: In the 5year study period, 21 hemodynamically unstable pelvic bone fracture patients were admitted; ten were men (47.6%), and 11 were women (52.4%). The mean age was 41.1 years (range: ${\pm}20.1$). Of the 21 embolization was performed in 6 patient (28.6%): 1 patient of the 5 unstable pelvic bone fracture patients (20%), and 5 patients of 16 the stable pelvic bone fracture patients (31.3%). There were no significant differences between the RTS (p=0.587) and embolization rate (p=0.774) for either the stable patients or the unstable patients. Patients with arterial injury on angiography had a lower RTS compared with patients without arterial injury but there was no significant difference in ISS between the two groups. The angiographic injured sites were five internal femoral arteries and one external femoral artery. Conclusion: The findings in this study suggest that the pelvic fracture pattern in hemodynamically unstable patients with pelvic fractures does not correlate with pelvic angiography findings.

• Journal of Korean Neurosurgical Society
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• v.64 no.6
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• pp.944-949
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• 2021

Objective : The stability is an important factor to decide the treatment plan in thoracolumbar burst fracture patients. Patients with an unstable burst fracture generally need operative management. Decrease in vertebral body height, local kyphosis, involvement of posterior column, and/or canal compromise are considered important factors to determine the treatment plan. On the other hand, in thoracolumbar injury classification system (TLICS), surgery is recommended in patients with TLICS of more than 5 points. The purpose of this study was to apply the TLICS score in patients with thoracolumbar burst fractures and to distinguish the differences of treatment plan on burst fracture. Methods : All patients, diagnosed as a thoracolumbar burst fracture between January 2006 and February 2019 were included in this study. Unstable thoracolumbar burst fracture was defined as burst fracture with neurologic deficit, three-column injury, kyphosis over 30 degrees, decrease of anterior body height over 40 percent and canal comprise more than 50%. TLICS score was measured with morphology, neurological involvement and posterior ligamentous complex integrity. The existence of instability was compared with TLICS score. Results : Total 233 patients (131 men, 102 women) were included in this study. In Denis classification, 51 patients (21.9%) diagnosed as stable burst fracture while 182 patients (78.1%) had unstable burst fracture. According to TLICS, 72 patients (30.9%) scored less than 4, while 161 patients (69.1%) scored 4 or more. All the patients with stable burst fracture scored 2 in TLICS. Twenty-one patients (9.0) scored 2 in TLICS but diagnosed as unstable burst fracture. Thirteen patients had over 40% of vertebra body compression, four patients had more than 50% of canal compromise, three patients had both body compression over 40% and kyphosis over 30 degrees, one patients had both body compression and canal compromise. Fifteen patients presented kyphosis over 30 degrees, and three (20%) of them scored 2 in TLICS. Seventy-three patients presented vertebral body compression over 40% and 17 (23.3%) of them scored 2 in TLICS. Fifty-three patients presented spinal canal compromise more than 50%, and five (9.4%) of them scored 2 in TLICS. Conclusion : Although the instability of thoracolumbar burst fracture was regarded as a critical factor for operability, therapeutic strategies by TLICS do not exactly match with the concept of instability. According to the concept of TLICS, it should be reconsidered whether the unstable burst fracture truly unstable to do operation.

• Journal of the Chungcheong Mathematical Society
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• v.29 no.1
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• pp.23-28
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• 2016

In this paper, we obtain close characterizations of flows near a saddle set which is one of the interesting unstable closed sets. Also, we consider some conditions that closed sets are to be stable.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.459-465
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• 1996

This paper is about unstable behavior in concrete during the localized deformation and the crack growths in concrete. By modeling the strain localization phenomenon of concrete, the stability condition of the localization is obtained and analyzed. And the stability and bifurcation condition of crack growths in two parallel cracks under different loading conditions are derived and discussed.