Jia Hao Chang

Comparison of EMG Activity Between Maximal Manual Muscle Testing and Cybex Maximal Isometric Testing of the Quadriceps Femoris

Two methods have been used to produce a maximal voluntary isometric contraction (MVIC) of the superficial quadriceps femoris muscles for normalization of electromyographic (EMG) data. The purposes of this study were to compare the myoelectic activity of MVIC of manual muscle testing (MMT) versus Cybex maximal isometric testing. Eighteen normal subjects were recruited. MMT and Cybex testing for MVIC of the dominant leg were performed. EMG activities of the vastus medialis, vastus lateralis and rectus femoris were recorded during MMT and Cybex trials. EMG amplitude and median frequency obtained from the two methods (MMT and Cybex testing) were used for statistical analysis of these three muscles. Statistically, the difference in the mean of the EMG signal amplitude and median frequency between MMT and Cybex testing were not significant. Considering cost and time, MMT for MVIC technique appears to be reliable and highly valuable.

Kinematics of cervical spine discectomy with and without bone grafting: Quantitative evaluation of late fusion in a sheep model

OBJECTIVEnThis study was conducted to evaluate the kinematic response of late fusion results for cervical spine discectomies with and without bone grafting.nnnMATERIALS AND METHODSnFifteen Barbados Black Belly sheep underwent sham operations (Group A, n = 5), C2-C3 discectomies only (Group B, n = 5), and C2-C3 discectomies with autologous iliac bone grafting (Group C, n = 5). Ten months after surgery, the animals were killed. Fresh ligamentous spines (C1-C5) were subjected to the relevantly applied loads through a loading frame attached to the C1. Each vertebra (from C2 to C4) was attached with a set of three infrared light-emitting diodes to record the spatial location relating to each load application using a Selspot II system (Selcom Selective Electronics, Inc., Valdese, NC). The load-deformation data of the C2-C3 and C3-C4 motion segments were recorded and analyzed for the three groups.nnnRESULTSnAt the C2-C3 motion segment, the results indicated that Group B displayed larger motion ranges of rotation and lateral bending loads than did the other two groups. Significantly larger motion ranges of rotation loads were found in Group B than in Group C (P<0.05, for both comparisons). In contrast, Group C had the smallest motion ranges of flexion, lateral bending, and rotation loads. At the C3-C4 motion segment, both groups that had undergone discectomies had a significantly larger motion range of flexion load compared with Group A (P<0.05, for both comparisons). A significant increase in the motion range of right axial rotation was found in Group B (P<0.05), but not in Group C, compared with Group A. Group B exhibited larger motion ranges responding to all six tested loads than did Group C.nnnCONCLUSIONnThe results indicate that anterior fusion after C2-C3 cervical discectomies, regardless of the presence or absence of bone grafting, decreases the motion range of flexion load at the C2-C3 motion segment, and contrary data were seen at the C3-C4 motion segment. For axial rotation loads, discectomies without bone grafting resulted in increased motion ranges of both C2-C3 and C3-C4 motion segments whereas discectomies with bone grafting did not. The data may have clinical relevance regarding the role of bone grafting in cases of cervical spine disease.

Loading effects of anterior cervical spine fusion on adjacent segments

Adjacent segment degeneration typically follows anterior cervical spine fusion. However, the primary cause of adjacent segment degeneration remains unknown. Therefore, in order to identify the loading effects that cause adjacent segment degeneration, this study examined the loading effects to superior segments adjacent to fused bone following anterior cervical spine fusion. The C3–C6 cervical spine segments of 12 sheep were examined. Specimens were divided into the following groups: intact spine (group 1); and C5–C6 segments that were fused via cage‐instrumented plate fixation (group 2). Specimens were cycled between 20° flexion and 15° extension with a displacement control of 1°/second. The tested parameters included the range of motion (ROM) of each segment, torque and strain on both the body and inferior articular process at the superior segments (C3–C4) adjacent to the fused bone, and the position of the neutral axis of stress at under 20° flexion and 15° extension. Under flexion and Group 2, torque, ROM, and strain on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. Under extension and Group 2, ROM for the fused segment was less than that of Group 1; torque, ROM, and stress on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. These analytical results indicate that the muscles and ligaments require greater force to achieve cervical motion than the intact spine following anterior cervical spine fusion. In addition, ROM and stress on the bodies and facets of the joint segments adjacent to the fused bone were significantly increased. Under flexion, the neutral axis of the stress on the adjacent segment moved backward, and the stress on the bodies of the segments adjacent to the fused bone increased. These comparative results indicate that increased stress on the adjacent segments is caused by stress‐shielding effects. Furthermore, increased stress and ROM of the adjacent segments after long‐term bone fusion may accelerate degeneration in adjacent segment.

Evaluation of unilateral cage-instrumented fixation for lumbar spine

BackgroundTo investigate how unilateral cage-instrumented posterior lumbar interbody fusion (PLIF) affects the three-dimensional flexibility in degenerative disc disease by comparing the biomechanical characteristics of unilateral and bilateral cage-instrumented PLIF.MethodsTwelve motion segments in sheep lumbar spine specimens were tested for flexion, extension, axial rotation, and lateral bending by nondestructive flexibility test method using a nonconstrained testing apparatus. The specimens were divided into two equal groups. Group 1 received unilateral procedures while group 2 received bilateral procedures. Laminectomy, facectomy, discectomy, cage insertion and transpedicle screw insertion were performed sequentially after testing the intact status. Changes in range of motion (ROM) and neutral zone (NZ) were compared between unilateral and bilateral cage-instrumented PLIF.ResultsBoth ROM and NZ, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF, transpedicle screw insertion procedure did not revealed a significant difference between flexion-extension, lateral bending and axial rotation direction except the ROM in the axial rotation. The bilateral groups ROM (-1.7 ± 0. 8) of axial rotation was decreased significantly after transpedicle screw insertion procedure in comparison with the unilateral group (-0.2 ± 0.1). In the unilateral cage-instrumented PLIF group, the transpedicle screw insertion procedure did not demonstrate a significant difference between right and left side in the lateral bending and axial rotation direction.ConclusionsBased on the results of this study, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF have similar stability after transpedicle screw fixation in the sheep spine model. The unilateral approach can substantially reduce exposure requirements. It also offers the biomechanics advantage of construction using anterior column support combined with pedicle screws just as the bilateral cage-instrumented group. The unpleasant effect of couple motion resulting from inherent asymmetry was absent in the unilateral group.

Biomechanical analysis of axial distraction mobilization of the glenohumeral joint – A cadaver study

The axial distraction mobilization techniques are frequently employed for treating patients with joint hypomobility. However, there is a lack of basic biomechanical studies and description of this procedure. The purpose of this study was to analyze humeral head displacement while performing an axial distraction mobilization of the glenohumeral joint. Twelve experienced orthopedic physical therapists participated. Distraction mobilization techniques were performed in three different positions of glenohumeral abduction on a fresh cadaveric specimen. Outcome measures were displacements of the humeral head center during distraction mobilization. Result indicated that displacement of the humeral head was largest in the resting position (27.38 mm) followed by the neutral (22.01 mm) and the end range position (9.34 mm). There were significant differences for both the displacement of the humeral head (p<0.002) and the distraction forces used (p<0.015) among the three joint positions. Greater gain in mobility was obtained in distraction at the end range position. In conclusion, during distraction mobilization, the force applied by the therapist and displacement of the humeral head depends on the joint position tested. Our results also provide rationales for choosing end range distraction mobilization for improving joint mobility.

Flatfoot diagnosis by a unique bimodal distribution of footprint index in children

Background More than 1000 scientific papers have been devoted to flatfoot issue. However, a bimodal distribution of flatfoot indices in school-aged children has never been discovered. The purposes of this study were to establish a new classification of flatfoot by characteristic in frequency distribution of footprint index and to endue the classification with discrepancy in physical fitness. Methods/Principal Findings In a longitudinal survey of physical fitness and body structure, weight bearing footprints and 3 physical fitness related tests were measured in 1228 school-aged children. Frequency distribution of initial data was tested by Kolmogorov-Smirnov test for normality and a unique bimodal distribution of footprint index was identified. The frequency distribution of footprint index manifests two distinct modes, flatfoot and non-flatfoot, by deconvolution and bootstrapping procedures. A constant intersection value of 1.0 in Stahelis arch index and 0.6 in Chippaux-Smirak index could distinguish the two modes of children, and the value was constant in different age, sex, and weight status. The performance of the one leg balance was inferior in flatfoot girls (median, 4.0 seconds in flatfoot girls vs. 4.3 seconds in non-flatfoot girls, pu200a=u200a0.04, 95% CI 0.404–0.484). Discussion The natural bimodality lends itself to a flatfoot classification. Bimodality suggests development of the childs foot arch would be a leap from one state to another, rather than a continuous growth as body height and weight. The underlying dynamics of the human foot arch and motor development will trigger research prospects.

Effects of pilates on patients with chronic non-specific low back pain: A systematic review

[Purpose] To evaluate the effects of Pilates on patients with chronic low back pain through a systematic review of high-quality articles on randomized controlled trials. [Subjects and Methods] Keywords and synonyms for “Pilates” and “Chronic low back pain” were used in database searches. The databases included PubMed, Physiotherapy Evidence Database (PEDro), Medline, and the Cochrane Library. Articles involving randomized controlled trials with higher than 5 points on the PEDro scale were reviewed for suitability and inclusion. The methodological quality of the included randomized controlled trials was evaluated using the PEDro scale. Relevant information was extracted by 3 reviewers. [Results] Eight randomized controlled trial articles were included. Patients with chronic low back pain showed statistically significant improvement in pain relief and functional ability compared to patients who only performed usual or routine health care. However, other forms of exercise were similar to Pilates in the improvement of pain relief and functional capacity. [Conclusion] In patients with chronic low back pain, Pilates showed significant improvement in pain relief and functional enhancement. Other exercises showed effects similar to those of Pilates, if waist or torso movement was included and the exercises were performed for 20 cumulative hours.

The effect of tai chi chuan on obstacle crossing strategy in older adults

The purpose of this study was to determine the effect of Tai Chi Chuan on the strategies of obstacle-crossing behavior in older adults aged over 65 years. Fifteen Tai Chi group (TCG) participants were compared with 15 general group (GG) participants. Kinematic parameters (by Vicon motion analysis system) and ground reaction forces (by Kistler force plates) were synchronously recorded. A two-way mixed-design ANOVA (α = 0.05) was used to test the effects of the group and the obstacle height. The TCG performed significantly faster stride velocities, longer stride lengths, and shorter stride times than GG while crossing the obstacles. TCG could also produce significantly larger forward ground reaction forces to propel the body and were able to make a significantly greater flexion angle of the hip of the leading leg compared with the GG. It was concluded that the TCG adopted a different strategy with GG to cross the obstacles and completed the crossing behavior more effectively.

Ground reaction force characteristics of Tai Chi push hand

Abstract Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s−1) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant’s body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.

BIOMECHANICAL CHARACTERISTICS IN YOGA SIRSASANA

The aim of this study was to understand how to process Yoga headstand and the difference between genders in headstand. Twelve skilled participates were recruited in this study (Males 34.1 ± 3.3 years, N=6; Females 36.5 ± 3.9 years, N=6). The 10 camera Vicon motion capture system, Kistler force plate, and Medilogic pressure mat were used synchronously to record the movement, ground reaction force, and pressure distribution during headstand. The Mann–Whitney U test and Friedman test (α=0.05) was applied to assess the statistics. The trunk, hip, knee, and ankle joint angles were −0.4±2.6∘, −0.8±4.1∘, −0.2±5.0∘, and 23.4±8.3∘, respectively, in all subjects. The pressure distribution was 38 ± 19%, 29 ± 12%, and 33 ± 9% on subjects’ heads, right elbows, and left elbows, respectively. The COP trajectory was 31.2 ± 17.4cm and surface area was 5.3 ± 1.4cm2. No significant differences were found in joint angles, overall force distribution, and COP trajectory and surface area between genders. Both males and females distribute body weight to the supports of head and elbows equally and kept the body straight and erect on the ground during Yoga headstand.