Paul S. Sung

Lumbar spine stability for subjects with and without low back pain during one-leg standing test.

Study Design. An experimental design comparing kinematic changes in the lumbar spine axis in subjects with and without low back pain (LBP) while standing on one leg with and without visual feedback. Objective. The purpose of this study was to evaluate the lumbar stability index, which includes relative holding time (RHT) and relative standstill time (RST), in subjects with and without LBP. Summary of Background Data. Even though a number of studies have evaluated postural adjustments based on kinematic changes in subjects with LBP, lumbar spine stability has not been examined for abnormal postural responses with visual feedback. Methods. All participants were asked to maintain the stork test position (standing on one leg with the contra lateral hip flexed 90°) for 25 seconds. The outcome measures included RHT and RST for the axes of the core spine and lumbar spine. Independent t tests were used to compare the differences between groups. Two-way repeated measure analysis of variance was used to compare the differences for both axes. The age variable was used as a covariate to control confounding effects for the data analyses. Results. The RHT was longer for the lumbar spine axis in subjects without LBP than those with LBP, especially without visual feedback. There was also significant interaction in RST between subjects with and without LBP (F = 7.18, P = 0.01). For the core axis of the trunk, significant differences existed based on the main effect of side (F = 9.07, P = 0.004), trunk rotation (F = 24.30, P = 0.001), and both of these interactions (F = 8.93, P = 0.004). However, there was a lack of significant interaction with age for the lumbar and core spine axes (F = 0.06, P = 0.81). Conclusion. Although the control group included slightly younger volunteers compared with the LBP group, the stability index of the core spine significantly decreased in RHT and RST, especially when visual feedback was blocked for subjects with LBP. The interaction between visual feedback and trunk rotation indicated that core spine stability is critical in coordinating balance control. A trunk muscle imbalance may contribute to unbalanced postural activity, which could prompt a decreased, uncoordinated bracing effect in subjects with LBP. As a result, core spine training could be used in the prevention of postural instability in such subjects.

A kinematic and kinetic analysis of spinal region in subjects with and without recurrent low back pain during one leg standing.

BACKGROUNDnThe purpose of this study was to evaluate the relationship between normalized kinematic and kinetic stability indices for spinal regions with eyes-open and eyes-closed conditions during non-dominant leg standing between subjects with recurrent low back pain and control subjects.nnnMETHODSnThe kinematic stability index for the spinal regions (core spine model, lumbar spine, lower and upper thorax) and the kinetic stability index from force plate were measured. All participants were asked to maintain non-dominant leg standing with the dominant hip and knee flexed approximately 90 degrees for 25 seconds. Forty-two participants enrolled in the study, including 22 subjects with low back pain (12 male, 10 female) and 20 control subjects (12 male, 8 female).nnnFINDINGSnFor the kinematic index for stability, the visual condition (F=30.06, p=0.0001) and spinal region (F=10.82, p=0.002) were statistically significant. The post hoc test results indicated a significant difference in the lumbar spine compared with the upper and lower thorax and the core spine model. The kinetic stability (average [standard deviation]) during the eyes-closed condition significantly decreased in the low back pain group (t=-3.24, p=0.002).nnnINTERPRETATIONnThe subjects with recurrent low back pain demonstrated higher lumbar spine stability in eyes-open condition. This higher stability of the lumbar spine might be due to a possible pain avoiding strategy from the standing limb. The low back pain group also significantly decreased kinetic stability during the eyes-closed condition. Clinicians need to consider both kinetic and kinematic indices while considering visual condition for lumbar spine stability in subjects with recurrent low back pain.

A kinematic analysis for shoulder and pelvis coordination during axial trunk rotation in subjects with and without recurrent low back pain.

The purpose of this study was to compare the kinematics of the shoulder and pelvis based on range of motion (ROM), angular velocity, and relative phase (RP) values during trunk axial rotation. Nineteen subjects with recurrent low back pain (LBP) and 19 age-matched control subjects who are all right limb dominant participated in this study. All participants were asked to perform axial trunk rotation activities at a self-selected speed to the end of maximum range in a standing position. The outcome measures included ROM, angular velocity, and RP on the shoulder and pelvis in the transverse plane and were analyzed based on the demographic characteristics between groups. The LBP group demonstrated decreased ROM (p=0.02) and angular velocity (p=0.02) for the pelvis; however, there was no group difference for the shoulder girdle. The ROM difference between the shoulder and pelvic transverse planes had a significant interaction with age (F=14.75, p=0.001). The LBP group demonstrated a higher negative correlation between the shoulder (r=-0.74, p=0.001) and pelvis (r=-0.72, p=0.001) as age increased while no significant correlations were found in the control group. The results of this study indicated that there was a difference in pelvic rotation in the transverse plane between groups during axial trunk rotation. It would be important to coordinate postural stability between the shoulder and pelvic girdles during ambulation; however, the pattern of trunk movement decreased with age due to possible pelvic stiffness in subjects with recurrent LBP. Therefore, improved pelvic flexibility for coordinated trunk movement patterns would help subjects with recurrent LBP.

Analysis of relative kinematic index with normalized standing time between subjects with and without recurrent low back pain

PurposeAlthough subjects with recurrent low back pain (LBP) demonstrate altered postural control, their postural steadiness during one leg standing is unknown. The purpose of this study was to investigate postural steadiness based on relative kinematic index of the lower limbs and trunk with normalized standing time in subjects with recurrent LBP during dominant and non-dominant leg standing.MethodsSixty individuals participated in the study, including 29 subjects in the control group (18 male, 11 female) and 31 subjects with recurrent LBP (21 male, 10 female). The outcome measures included relative kinematic index of the body regions and normalized standing time during the one leg standing test. The relative kinematic index was the ratio between standstill time and successful standing time. The normalized standing time was defined as a ratio between the successful standing time and the requested standing time.ResultsThe control group demonstrated significantly longer normalized standing time on the dominant (txa0=xa0−2.57, pxa0=xa00.013) and non-dominant (txa0=xa0−2.78, pxa0=xa00.007) legs than the LBP group. The relative kinematic index of the core spine model significantly decreased for the dominant (txa0=xa0−3.01, pxa0=xa00.004) and non-dominant (txa0=xa0−3.06, pxa0=xa00.003) legs in the LBP group. In addition, the kinematic index indicated pelvis and non-dominant shank during dominant leg standing (R2xa0=xa00.97) in the LBP group. In the control group, the pelvis was significantly correlated with the core spine model during standing on the dominant (R2xa0=xa00.95) and non-dominant (R2xa0=xa00.97) legs.ConclusionsThe relative kinematic index of the pelvis was found to be most significant for longer standing durations in both groups. In the LBP group, the shank and foot were significantly higher in addition to the pelvis due to possible compensatory motion. The control group took advantage of pelvic control with the core spine to minimize lower limb movements. Clinicians need to consider the core spine for pelvic control to refine postural adaptations in subjects with recurrent LBP.

Different coordination and flexibility of the spine and pelvis during lateral bending between young and older adults.

This study examined coordination of the spine and pelvis during lateral bending of the trunk in older adults. Thirty-four healthy subjects (17 young and 17 older adults) demonstrated lateral bending at a controlled speed while holding a bar at approximately 180 degrees of shoulder flexion. Kinematic data collection was completed on the thoracic spine, lumbar spine, and pelvis. The coupling angle was calculated to examine the thorax-lumbar, lumbar-pelvis, and thorax-pelvis coordination patterns. The older adults demonstrated a reduced range of motion (ROM) of the lumbar spine, while both groups revealed similar ROM in the thorax and in the pelvis. The coupling angle between the straightening and bending phases was different only for the older adults in the thorax-lumbar (23.4±8.0 vs. -1.6±4.4, p=0.004) and the lumbar-pelvis (65.4±7.2 vs. 86.1±7.8, p=0.001) coordination. However, there was no group difference in the thorax-pelvis coordination. These findings indicate that age-related changes in the lumbar region affect coordination patterns only during the bending phase. The older adults preserved a similar pattern of movement to the young adults during the straightening phase, but the coordination variability of the coupling angles was greater for the older adults than for the young adults. This movement pattern suggests that the older adults lacked consistent trunk control in an attempt to optimize lateral bending coordination.

Comparison of the different kinematic patterns during lateral bending between subjects with and without recurrent low back pain

BACKGROUNDnLateral bending is a prerequisite for various functional activities of daily life, which require combined three-dimensional motion. Even though a number of studies have evaluated spinal kinematic changes during lateral bending, the literature reveals a lack of data based on limb dominance. The purpose of this study was to compare kinematic angular displacement of the spinal regions for dominant and non-dominant lateral bending in subjects with and without recurrent low back pain.nnnMETHODSnForty-four right hand dominant individuals with recurrent low back pain (43.1 [17.4] years) and without low back pain (39.7 [18.7] years) participated in this study. All participants were asked to perform trunk lateral bending to the dominant and non-dominant sides with a bar, three times repeatedly. The outcome measures included three-dimensional angular displacements for the three regions of the spine (upper thorax, lower thorax, and lumbar spine).nnnFINDINGSnLumbar rotation (degrees) increased to the dominant side in the low back pain group (9.29 [1.06]) compared to the control group (6.20 [1.02]) with increased rotation in the upper thorax as well (t=-2.09, p=0.04). However, the upper thorax rotation increased in the low back pain group to the non-dominant side (t=2.08, p=0.03) and to the dominant side (t=-2.35, p=0.02). There was a group interaction with planes (F=5.82, p=0.02) during lateral bending.nnnINTERPRETATIONnAlthough lower thorax motion was not different between groups, increased lumbar spine and upper thorax rotations to the dominant side in the low back pain group were evident during lateral bending. This directional asymmetry should be carefully monitored to understand increased lumbar rotation to the dominant side in subjects with recurrent low back pain. The interactions between group and plane explain compensation strategies through increased lumbar rotation to the dominant side with decreased lateral bending of the upper thorax in subjects with recurrent low back pain.

Reliability of the Kinematic Steadiness Index during one-leg standing in subjects with recurrent low back pain

PurposeTo assess the reliability of standing time and the Kinematic Steadiness Index (KSI) in one-leg standing compared with the Timed Up and Go (TUG) test while considering anthropometric factors in subjects with recurrent low back pain (LBP).MethodsSixty-six individuals participated in the study. The data were collected on two different days, 1xa0week apart. The KSI of the core spine, using video motion-capture techniques, was based on the relative standing time and relative standstill time. The intraclass correlation coefficient (ICC2,1) was compared for the reliability between measures. The covariates, such as age, Body Mass Index, and the Oswestry Disability Index (ODI), were analyzed for any interactions based on these measures.ResultsThe standing time (txa0=xa0−xa01.01, pxa0=xa00.32) and the KSI (txa0=xa0−xa01.70, pxa0=xa00.09) were not significantly different between measures. The TUG results were not different between measures (txa0=xa01.01, pxa0=xa00.32). The Cronbach’s alpha for the standing time was 0.84, for KSI was 0.89, and for TUG was 0.76. The standing time and KSI demonstrated an interaction with age, while the TUG demonstrated an interaction with the ODI score.ConclusionsThe KSI during one-leg standing could help to develop a practical tool to justify quantity and quality of balance outcome measures, which identify balance deficits and core spine rehabilitation strategies in subjects with recurrent LBP.

Gender differences in asymmetrical limb support patterns between subjects with and without recurrent low back pain

New insight regarding limb-dominance effects on temporal-spatial gait parameters is needed to further investigate subjects with recurrent low back pain (LBP). Although an asymmetrical gait pattern was found to reflect natural functional differences, there is a lack of information regarding gender differences on dominant limb support patterns in subjects with LBP. The purpose of this study was to investigate temporal-spatial gait parameters based on limb dominance and gender between subjects with and without LBP. One hundred and ten right limb dominant older adults (51 subjects with LBP and 59 control subjects) participated in the study. A three-dimensional motion capture system was utilized to measure temporal-spatial gait parameters, including initial double, single, and terminal double limb support times and walking speed. The gender differences between subjects with and without LBP were analyzed based on dominance for those parameters. Overall, limb dominance demonstrated significant differences on single and terminal double limb support times as well as walking speed. Limb dominance also demonstrated interactions on group x gender for single limb support time and walking speed. The male subjects with LBP demonstrated significantly increased single limb support times on the non-dominant limb. The significant gender and group interactions based on limb dominance account for a possible pain avoidance, asymmetrical limb support pattern. The causal pathway in dominance dependency gait by unweighted ambulation might be considered as an intervention for correcting these gait deviations in subjects with LBP. The specific modification recovery profiles of the subjects with LBP could shed light on variability of current LBP experiences of the subjects and reasons for gait deviations. Clinicians need to consider the mechanism of dominant limb dependency, which requires postural control strategies in male subjects with recurrent LBP.

Gender difference of shoulder-pelvic kinematic integration for trunk rotation directions in healthy older adults

Background: The trunk coordination pattern has been extensively studied, and there is a higher pain prevalence and asymmetry in female older adults. However, there is a lack of investigation of different directions of trunk rotation and asymmetrical compensatory strategies of motor control between genders. The purpose of this study was to investigate shoulder and pelvic ranges of motion (ROM) as well as relative phases (RP) for the different directions of trunk rotation between genders in healthy older adults. Methods: There were 62 right hand dominant older adults in this study (31 female subjects (68.4 [5.62] years) and 31 male subjects (68.7 [5.68] years)). The participants performed trunk axial rotation from the left to the right direction (RP1) and then returned to the left side (RP2), three times repeatedly in standing. The measurements included shoulder and pelvic ROM, RP1, and RP2. The RP was defined as the average absolute relative phase, which was the difference between the phase angle of the shoulder and the phase angle of the pelvis during trunk rotation. Findings: The female group demonstrated significantly greater pelvic rotation compared to the male group (98.64 [24.67] vs. 86.96 [18.97]; t = 2.09, p = 0.04) during trunk rotation. The pelvic ROM demonstrated a significant positive correlation with shoulder ROM in both genders; however, the RP was negatively correlated with the pelvis. For pelvic rotation, the male group demonstrated a negative correlation with RP1 (r = − 0.68, p < 0.01) and RP2 (r = − 0.60, p < 0.01) while the female group demonstrated a negative correlation with RP2 (r = − 0.53, p < 0.01). The ageing factor demonstrated negative correlations with ROM for the shoulder and pelvis in both genders. Interpretation: Although no gender difference was indicated on the direction of RP, the pelvic ROM was significantly lesser in the male group. The male group demonstrated lesser pelvic rotation in both directions of rotation; however, the female group showed lesser pelvic rotation in RP2. The male group demonstrated stiffened pelvic rotation and greater shoulder rotation in both directions while the female group demonstrated pelvic stiffness only in the direction from right to left rotation. Clinicians need to consider this directional asymmetry of trunk rotation to enhance integrated shoulder‐pelvic coordination in female older adults. Mini abstract: A coordinative pattern of different directions of trunk rotation was investigated in healthy older adults. The pelvic range of motion was lesser in the male group compared with the female group. The female group demonstrated pelvic stiffness only in the direction from right to left rotation, while the male group demonstrated pelvic stiffness in both directions. Clinicians need to understand the gender difference of directional coordination as integrated coordination in female older adults. HighlightsThe ageing factor was negatively correlated with shoulder and pelvic range of motion.The female group demonstrated less pelvic rotation in the right to left rotation phase.The directional asymmetry of trunk rotation in the female group needs to be considered.

Kinematic analysis of ankle stiffness in subjects with and without flat foot

BACKGROUNDnAlthough the magnitude of ankle motion is influenced by joint congruence and ligament elasticity, there is a lack of understanding on ankle stiffness between subjects with and without flat foot.nnnOBJECTIVEnThis study investigated a quantified ankle stiffness difference between subjects with and without flat foot.nnnMETHODSnThere were forty-five age- and gender-matched subjects who participated in the study. Each subject was seated upright with the tested foot held firmly onto a footplate that was attached to a torque sensor by the joint-driving device.nnnRESULTSnThe flat foot group (mean ± standard deviation) demonstrated increased stiffness during ankle dorsiflexion (0.37 ± 0.16 for flat foot group, 0.28 ± 0.10 for control group; t=-2.11, p=0.04). However, there was no significant group difference during plantar flexion (0.35 ± 0.15 for flat foot group, 0.33 ± 0.07 for control group; t=0.64, p=0.06).nnnCONCLUSIONnThe results of this study indicated that the flat foot group demonstrated increased ankle stiffness during dorsiflexion regardless of demographic factors. This study highlights the need for kinematic analyses and joint stiffness measures during ankle dorsiflexion in subjects with flat foot.