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The Mechanical Behaviour of the Scaroiliac Joint
Ho-Jung Cho(조호정),Eunah Hong(홍은아),Dai-Soon Kwak(곽대순) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Dysfunctional sacroiliac joint (SIJ) was considered as a source of the lower back pain. Several researchers investigated anatomy and biomechanics of the SIJ to understand the relationship between the lower back pain and the SIJ. Many studies concluded the SIJ has little movement. However, some of the studies using spinopelvic parameters mentioned high pelvic incidence (PI) change. Moreover, with the development of imaging techniques such as EOS system and vertical CT / MR, interest in sacroiliac joint movement and sagittal balance is increasing. Therefore, in this study, the movement characteristics of the sacroiliac joint were investigated by constructing an environment that could be measured and controlled more precisely than in past experiments. We used six fresh cadavers (male 1, female 5). The mean age was 85.25 (81~92) years and the mean height was 152.47 (142~161) cm. The pelvis was harvested by dissection. The hip bone, sacrum, coccyx, and ligaments between hip bone and sacrum were preserved. Patient-specific spacer blocks for fixation of the sacrum were designed by CT images and printed by a 3D printer. 3D printed patient-specific spacer blocks were fixated at the anterior and posterior surface of the sacrum, and the sacrum with the spacer blocks was fully fixated. The external load was applied in superior (+) and inferior (-) directions at pubic symphysis. Hip bone tilt angle, the movement of the pubic symphysis, and posterior superior iliac spine were measured with applied load. For these measurements, 13 optical markers and 4 motion capture cameras were used. We observed the remarkable SIJ movements in the female pelvis in 5 of 6 samples. However, only small movements were observed (-1.25 degrees and 1.90 degrees at +/- 200N, respectively). In the sample where the movement was observed, the hip bone tilt angle was 3.93 ± 0.49° under +100N and 4.86 ± 0.39° when applied with +200N. The tilt angle was 3.27 ± 1.42° when -100N was applied and 5.76 ± 1.63º applied with -200N (Fig. 2). The movement of the pubic symphysis was small (within 0.35 mm) in all cases, and the movement of the PSIS was 0.69 ± 0.52 mm, 0.70 ± 0.72 mm, 0.54 ± 0.02 mm, 0.79 ± 0.02 mm at +100N, +200N, -100N, and -200N respectively. Regardless of the loading direction, it showed an outward-opening behavior. The SIJ is a joint in which +/- 5 degrees of movement can occur due to weight bearing or muscle action, and this behavior should be considered in biomechanics studies. In particular, it mainly occurred in the pelvis of women, and studies on more samples are needed.
Lumbo-sacral and hip joint complex movement according to the asymmetric muscle contraction
Ho-Jung Cho(조호정),Eunah Hong(홍은아),Dai-soon Kwak(곽대순) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Poor posture or hypertonic of the specific muscle of the pelvis is one of the major causes of the musculoskeletal problem of the low back. Asymmetry contraction of the muscles which moved the pelvis could affect the lumbosacral-hip joint. Therefore, this study analysis pelvic movement according to the asymmetric muscle contraction around the pelvis. Five Korean adult cadavers were used to evaluate the pelvic movement (F: 1, M: 4), and the average age was 83.4years. To evaluate the pelvic movement, the specimen was harvested from the first lumbar to the femur. The gluteus maximus (GMax), hamstring (Ham), erector spinae (ES), and iliopsoas (IP) which known as occur the pelvic anterior (AT) and posterior tilt (PT) were dissected to evaluate the pelvic movement. The muscle contraction was generated through the customized device which was made using the linear actuator and load cell, and this device was designed to control the leg position. To analyze the pelvic on femoral motion with stationary supra-lumbar vertebrae, the vertebrae of the harvested specimen was fixed with a stainless rod and both femurs fixed. Also, the AT and PT were analyzed during muscle asymmetric contraction in both femurs fixed. Also, the lateral tilt and axial rotation were observed during the AT and PT. The continuous pelvic motions were analyzed using a motion analysis program and motion capture cameras. There were different joint coordination and joint imbalance in each sample even its alignment was checked before the test. Therefore, the ratio of the angle through each muscle was considered instead of the calculation of the average tilting angle. In the comparison of the PT angle ratio between the GMax and Ham in the same load, 3 samples showed a bigger movement ratio in the GMax than the Ham, and Ham movement ratio were 47.3%, 56.6%, and 77.7% than those of the GMax. One sample showed a similar movement ratio between both muscles, and the other showed that the movement ratio of the Ham was bigger than the GMax. During the GMax contraction, the pelvic was rotated in the axial plane, but Ham was not affected the axial rotation. Also, the pelvis was tilted laterally during the GMax contraction, it was only a slight degree less than 1° except for one sample (1.8°). In comparison to the AT through asymmetric contraction of the ES and IP, the asymmetric contraction of the ES occurred the AT bigger than those of the IP in all samples. However, the ratio of the movement was varied in each sample. Also, both ES and IP did not occur the lateral tilt and axial rotation. This study is still undergoing using more samples to analyze the pelvic tilt movement, and the additional quantification research about the relationship between the muscle force and pelvic movement is planning to use cross-sectional area of the muscle.
Continuous flexion-extension test of the knee joint using motion simulator
Ho-Jung Cho(조호정),Eunah Hong(홍은아),In-Jun Koh(고인준),Dohyung Lim(임도형),Dai-Soon Kwak(곽대순) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Many devices were developed to simulate the movement of the knee joint. We designed the knee joint simulator which could move flexion to extension of the knee joint continuously based on the Oxford knee simulator, and investigated the knee joint kinematics using the designed knee simulator. This study introduced the methods and results of the biomechanical test of the knee joint through the evaluation of the designed knee simulator, the preparation process of the cadavers, motion analysis using motion capture cameras and optic markers, and measurement of the surface strain using the video extensometer. To obtain the results of the motion analysis, the medial and lateral rollback of the knee and patella movements were measured using 12 optic markers, also, the results showed high repeatability. The video extensometer could measure the strain of the ligamentous structures during flexion and extension of the knee joint in real-time, and, this showed high repeatability in the test.
Changes of joint kinematics by alignment method in total knee arthroplasty
Ho-Jung Cho(조호정),Eunah Hong(홍은아),In-Jun Koh(고인준),Dohyung Lim(임도형),Dai-Soon Kwak(곽대순) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Recently, the kinematic alignment has been introduced as a total knee arthroplasty alignment method. It was known to reduce the initial heterogeneity in patients. In this study, we studied the changes in the knee joint's kinematics according to the alignment method. Eight pairs of cadavers were tested. For each pair, one knee was randomly assigned to the kinematic alignment TKA group (KA) and the other to the mechanical alignment TKA group (MA). During KA, the sizes of femur and tibia resections were equivalent to implant thickness. MA was performed using conventional measured resection techniques. All specimens were mounted on a customized knee-testing system, and knee motions included rollback, patella movement, were measured by a motion-analysis system during flexion. The pattern of knee motion following KA was similar to the native knee. However, following MA, both medial and lateral rollback were decreased relative to those of the native knee. In the patella movement, we found no significant difference according to the alignment method, but the KA showed similar with native knee relatively.