노인 낙상 - 넘어짐 그리고 인체손상의 과학, 넘어지면 다 죽는가? : 문헌 고찰

최우철(Woochol Joseph Choi),임기택(Kitaek Lim),김승수(Seung-su Kim),이세영(Se-young Lee) 한국전문물리치료학회 2021 한국전문물리치료학회지 Vol.28 No.3

Understanding sciences behind fall-related hip fractures in older adults is important to de-velop effective interventions for prevention. The aim of this review is to provide biomechanical understanding and prevention strategies of falls and related hip fractures in older adults, in order to guide future research directions from biomechanical perspectives. While most hip fractures are due to a fall, a few of falls are injurious causing hip fractures, and most falls are non-injurious. Fall mechanics are important in determining injurious versus non-injurious falls. Many different biomechanical factors contribute to the risk of hip fracture, and effects of each individual factors are known well. However, combining effects, and correlation and causation among the factors are poorly understood. While fall prevention interventions include exercise, vision correction, vitamin D intake and environment modification, injury prevention strategies include use of hip protectors, compliant flooring and safe landing strategies, vitamin D intake and exercise. While fall risk assessments have well been established, limited efforts have been made for injury risk assessments. Better understanding is necessary on the correlation and causation among factors affecting the risk of falls and related hip fractures in older adults. De-velopment of the hip fracture risk assessment technique is required to establish more efficient intervention models for fall-related hip fractures in older adults.

Neuromuscular Electrical Stimulation of Abdominal Muscles to Improve Standing Balance

Jeongwoo Je(Jeongwoo Je),Woochol Joseph Choi(Woochol Joseph Choi) 한국전문물리치료학회 2022 한국전문물리치료학회지 Vol.29 No.4

Background: Neuromuscular electrical stimulation (NMES) is used for muscle strengthening. While voluntary muscle contraction follows Henneman et al.’s size principle, the NMES-induced muscle training disrespects the neurophysiology, which may lead to unwanted changes (i.e., declined balance ability). Objects: We examined how the balance was affected by abdominal muscle training with the NMES. Methods: Fifteen young adults (10 males and 5 females) aged between 21 and 30 received abdominal muscle strengthening with NMES for 23 minutes. Before and after the training, participants’ balance was measured through one leg standing on a force plate with eyes open or closed. Outcome variables included mean distance (MDIST), root mean square distance (RDIST), total excursion (TOTEX), mean velocity (MVELO), and 95% confidence circle area (AREA) of center of pressure data. Two-way repeated measures analysis of variance was used to test if these outcome variables were associated with time (pre and post) and vision. Results: All outcome variables were not associated with time (p > 0.05). However, all outcome variables were associated with vision (p = 0.0001), and MVELO and TOTEX were 52.4% (45.5 mm/s versus 95.6 mm/s) and 52.4% (364.1 mm versus 764.5 mm) smaller, respectively, in eyes open than eyes closed (F = 55.8, p = 0.0005; F = 55.8, p = 0.0005). Furthermore, there was no interaction between time and vision (F = 0.024, p = 0.877). Conclusion: Despite the different neurophysiology of muscle contraction, abdominal muscle strengthening with NMES did not affect balance.

Falls in Patients of Medical Institutions in South Korea: A Literature Review

Jongwon Choi,Woochol Joseph Choi 한국전문물리치료학회 2023 한국전문물리치료학회지 Vol.30 No.1

Background: Like many other countries, falls and related injuries in older adults are great concerns in South Korea. In particular, falls are common in medical institutions, often causing the increase of the length of hospitalization. Objects: The purpose of this review was to help understand and address falls in hospitalized individuals in South Korea. Methods: The review was conducted on literature published in Korean from 2010 to 2022, searched in the Korea Citation Index and PubMed. Keywords used for the search were as fol-lows: falls, fall risk, fall risk assessment, hospital, inpatient, intervention, Korea, and preven-tion. Results: A total of 54 articles were found and reviewed. The most common place of fall ac-cidents was the inpatient room, where there were many cases of falls while walking. Loss of balance was the most common cause of falls, and many falls occurred in patients admitted to the internal medicine. Furthermore, a risk of falling increased with the type of medications taken. In terms of tools to assess patients’ fall risk, the Morse Fall Scale (MFS) was commonly used. Patient-specific fall prevention activities were common to address falls, and they de-creased the frequency of falls and the fear of falling. Factors influencing the effectiveness of the fall prevention activities included attitudes toward falls, education, environmental factors, patient safety culture, and self-efficacy in preventing falls. Conclusion: Our results should help understand and address falls and injuries in medical institutions.

Application of Decision Tree to Classify Fall Risk Using Inertial Measurement Unit Sensor Data and Clinical Measurements

Park Junwoo,Choi Jongwon,Lee Seyoung,Lim Kitaek,Choi Woochol Joseph 한국전문물리치료학회 2023 한국전문물리치료학회지 Vol.30 No.2

Background: While efforts have been made to differentiate fall risk in older adults using wearable devices and clinical methodologies, technologies are still infancy. We applied a decision tree (DT) algorithm using inertial measurement unit (IMU) sensor data and clinical measurements to generate high performance classification models of fall risk of older adults. Objects: This study aims to develop a classification model of fall risk using IMU data and clinical measurements in older adults. Methods: Twenty-six older adults were assessed and categorized into high and low fall risk groups. IMU sensor data were obtained while walking from each group, and features were extracted to be used for a DT algorithm with the Gini index (DT1) and the Entropy index (DT2), which generated classification models to differentiate high and low fall risk groups. Model’s performance was compared and presented with accuracy, sensitivity, and specificity. Results: Accuracy, sensitivity and specificity were 77.8%, 80.0%, and 66.7%, respectively, for DT1; and 72.2%, 91.7%, and 33.3%, respectively, for DT2. Conclusion: Our results suggest that the fall risk classification using IMU sensor data obtained during gait has potentials to be developed for practical use. Different machine learning techniques involving larger data set should be warranted for future research and development.

Feature Extraction and Evaluation for Classification Models of Injurious Falls Based on Surface Electromyography

Kitaek Lim,Woochol Joseph Choi 한국전문물리치료학회 2021 한국전문물리치료학회지 Vol.28 No.2

Background: Only 2% of falls in older adults result in serious injuries (i.e., hip fracture). Therefore, it is important to differentiate injurious versus non-injurious falls, which is critical to develop effective interventions for injury prevention. Objects: The purpose of this study was to a. extract the best features of surface electromy-ography (sEMG) for classification of injurious falls, and b. find a best model provided by data mining techniques using the extracted features.Methods: Twenty young adults self-initiated falls and landed sideways. Falling trials were consisted of three initial fall directions (forward, sideways, or backward) and three knee po-sitions at the time of hip impact (the impacting-side knee contacted the other knee (“knee together”) or the mat (“knee on mat”), or neither the other knee nor the mat was contacted by the impacting-side knee (“free knee”). Falls involved “backward initial fall direction” or “free knee” were defined as “injurious falls” as suggested from previous studies. Nine features were extracted from sEMG signals of four hip muscles during a fall, including integral of absolute value (IAV), Wilson amplitude (WAMP), zero crossing (ZC), number of turns (NT), mean of am-plitude (MA), root mean square (RMS), average amplitude change (AAC), difference absolute standard deviation value (DASDV). The decision tree and support vector machine (SVM) were used to classify the injurious falls. Results: For the initial fall direction, accuracy of the best model (SVM with a DASDV) was 48%. For the knee position, accuracy of the best model (SVM with an AAC) was 49%. Further-more, there was no model that has sensitivity and specificity of 80% or greater.Conclusion: Our results suggest that the classification model built upon the sEMG features of the four hip muscles are not effective to classify injurious falls. Future studies should con-sider other data mining techniques with different muscles.

Understanding the Biomechanical Factors Related to Successful Balance Recovery and Falls: A Literature Review

Junwoo Park,Jongwon Choi,Woochol Joseph Choi 한국전문물리치료학회 2023 한국전문물리치료학회지 Vol.30 No.1

Background: Despite fall prevention strategies suggested by researchers, falls are still a ma-jor health concern in older adults. Understanding factors that differentiate successful versus unsuccessful balance recovery may help improve the prevention strategies. Objects: The purpose of this review was to identify biomechanical factors that differentiate successful versus unsuccessful balance recovery in the event of a fall. Methods: The literature was searched through Google Scholar and PubMed. The following keywords were used: ‘falls,‘ ‘protective response,‘ ‘protective strategy,’ ‘automated postural response,’ ‘slips,’ ‘trips,’ ‘stepping strategy,‘ ‘muscle activity,’ ‘balance recovery,‘ ‘successful balance recovery,‘ and ‘failed balance recovery.’ Results: A total of 64 articles were found and reviewed. Most of studies included in this review suggested that kinematics during a fall was important to recover balance successfully. To be successful, appropriate movements were required, which governed by several things depending on the direction and characteristics of the fall. Studies also suggested that lower limb muscle activity and joint moments were important for successful balance recovery. Other factors associated with successful balance recovery included fall direction, age, appropriate protective strategy, overall health, comorbidity, gait speed, sex and anticipation of the fall. Conclusion: This review discusses biomechanical factors related to successful versus un-successful balance recovery to help understand falls. Our review should help guide future research, or improve prevention strategies in the area of fall and injuries in older adults.

Effects of Robot-assisted Gait With Body Weight Support on Torque, Work, and Power of Quadriceps and Hamstring Muscles in Healthy Subjects

Jihun Hwang,Sung (Joshua) Hyun You,Woochol Joseph Choi,Chung-hwi Yi 한국전문물리치료학회 2021 한국전문물리치료학회지 Vol.28 No.3

Background: Robot-assisted gait training (RAGT) is an effective method for walking reha-bilitation. Additionally, the body weight support (BWS) system reduces muscle fatigue while walking. However, no previous studies have investigated the effects of RAGT with BWS on isokinetic strength of quadriceps and hamstring muscles. Objects: The purpose of this study was to investigate the effects of torque, work, and power on the quadriceps and hamstring muscles during RAGT, using the BWS of three conditions in healthy subjects. The three different BWS conditions were BWS 50%, BWS 20%, and full weight bearing (FWB). Methods: Eleven healthy subjects (7 males and 4 females) participated in this study. The Walkbot_S was used to cause fatigue of the quadriceps and hamstring muscles and the Biodex Systems 4 Pro was used to measure the isokinetic torque, work, and power of them. After RAGT trials of each of the three conditions, the subjects performed isokinetic concentric knee flexion and extension, five at an angular velocity of 60°/s and fifteen at an angular velocity of 180°/s. One-way repeated analysis of variance was used to determine significant differences in all the variables. The least significant difference test was used for post-hoc analysis. Results: On both sides, there were significant differences in peak torque (PT) of knee exten-sion and flexion between the three BWS conditions at an angular velocity of 60°/s and 180°/s conditions. A post-hoc comparison revealed that the PT in the BWS 50% was significantly greater than in the BWS 20% and the FWB and the PT in the BWS 20% was significantly greater than in the FWB. Conclusion: The results of this study suggest that the lower BWS during RAGT seems to lower the isokinetic torque, work, and power of the quadriceps and hamstring muscles be-cause of the muscle fatigue increase.

Effect on the Center of Pressure of Vision, Floor Condition, and the Height of Center of Mass During Quiet Standing

Seung-su Kim,Kitaek Lim,Woochol Joseph Choi 한국전문물리치료학회 2021 한국전문물리치료학회지 Vol.28 No.2

Background: Theoretically, balance is affected by the height of center of mass (COM) during quiet standing. However, no one examined this in humans with variables derived from the center of pressure (COP). Objects: We have conducted balance experiment to measure COP data during quiet stand-ing, in order to examine how the COP measures were affected by the height of COM, vision, floor conditions, and gender.Methods: Twenty individuals stood still with feet together and arms at sides for 30 seconds on a force plate. Trials were acquired with three COM heights: 1% increased or decreased, and not changed, with two vision conditions: eyes closed (EC) and eyes open (EO), and with two floor conditions: unstable (foam pad) and stable (force plate) floor. Outcome variables included the mean distance, root mean square distance, total excursion, mean velocity, and 95% confidence circle area.Results: All outcome variables were associated with the COM height (p < 0.0005), vision (p < 0.0005), and floor condition (p < 0.003). The mean velocity and 95% confidence circle area were 5.7% and 21.8% greater, respectively, in raised COM than in lowered COM (24.6 versus 23.2 mm/s; 1,013.4 versus 832.3 mm2). However, there were no interactions between the COM height and vision condition (p > 0.096), and between the COM height and floor condition (p > 0.183) for all outcome variables. Furthermore, there was no gender difference in all outcome variables (p > 0.186).Conclusion: Balance was affected by the change of COM height induced by a weight belt in human. However, the effect was not affected by vision or floor condition. Our results should inform the design of balance exercise program to improve the outcome of the balance training.

Comparative Effects of Novel Modified Sleeper and Cross-body Stretching on Scapular Anterior Tilting and Shoulder Internal Rotation in Subjects With Anterior Tilted Scapular and Shoulder Internal Rotation Deficits

Yeonghun Han,Chung-hwi Yi,Woochol Joseph Choi,Oh-yun Kwon 한국전문물리치료학회 2023 한국전문물리치료학회지 Vol.30 No.1

Background: Posterior capsule tightness (PCT), commonly seen in overhead athletes, is a soft tissue adaptation that is also noted in non-throwers. PCT is associated with scapular and humeral kinematic alterations, significant restriction of shoulder internal rotation (IR) range of motion (ROM), and significant scapular anterior tilting. Sleeper and cross-body stretches (CBS) are suggested for PCT and IR deficits, and have been modified since introduction. A novel modified sleeper stretch (NMSS) was designed in this study to prevent the risk of anterior translation of the humeral head. Though the effects of posterior shoulder stretching exercise have been widely studies, to the best of our knowledge, no previous studies have investigated the effectiveness of posterior shoulder exercises in decreasing scapular anterior tilting. Objects: To compare the immediate effects of two posterior shoulder stretching exercises (NMSS and CBS) on scapular anterior tilting and shoulder IR ROM. Methods: Thirty-two subjects with anteriorly tilted scapula and IR deficits [mean age: 24.3 ± 2.5 years; 15 males and 17 females] participated in this study. Subjects were randomly assigned to either the NMSS or CBS groups. Scapular anterior tilting (at rest and at shoulder 60° active IR) and shoulder IR ROM were measured before and immediately after intervention. Results: Scapular anterior tilting significantly decreased, while the shoulder IR ROM signifi-cantly increased in both groups. However, there was no significant group-by-time interaction effect or significant difference between the groups. Conclusion: Both stretching exercises were effective in restoring shoulder IR ROM and de-creasing scapular anterior tilting.

Characterizing Viscoelastic Property of Soft Tissue Over the Hip as a Risk Factor of Pressure Ulcer

Kitaek Lim,Seung-su Kim,Woochol Joseph Choi 한국전문물리치료학회 2021 한국전문물리치료학회지 Vol.28 No.1

Background: A pressure ulcer is common in soft tissue over the greater trochanter (GT) in side-lying position, and sustained tissue deformation induced by the prolonged external force is a primary cause, which can be discussed with soft tissues’ viscoelastic properties (i.e., stress relaxation, creep response). Objects: Using an automated hand-held indentation device, we measured the viscoelastic properties of soft tissue over the hip area, in order to examine how the properties are affected by site with respect to the GT. Methods: Twenty participants (15 males and 5 females) who aged from 21 to 32 were participated. An automated hand-held indentation device was used to measure the stress relaxation time and creep response. Trials were acquired for three different locations with respect to the GT (i.e., right over the GT, 6 cm anterior or posterior to the GT). For each location, five trials were acquired and averaged for data analyses. Results: Soft tissues’ stress relaxation time and creep response were associated with site (F = 23.98, p < 0.005; F = 24.09, p < 0.005; respectively). The stress relaxation time was greatest at posterior gluteal region (19.22 ± 2.49 ms), and followed by anterior region (15.39 ± 2.47 ms) and right over the GT (14.40 ± 3.18 ms). Similarly, creep response was greatest at posterior gluteal region (1.16 ± 0.14), and followed by anterior region (0.95 ± 0.14) and right over the GT (0.89 ± 0.18). Conclusion: Our results showed that the stress relaxation and creep were greatest at the posterior gluteal region and least at right over the GT, indicating that the gluteal soft tissue is more protective to the prolonged external force, when compared to the trochanteric soft tissue. The results suggest that a risk of pressure ulcer over the GT may decrease with slightly posteriorly rotated side-lying position.