Hao-Ling Chen

Effects of severity of degeneration on gait patterns in patients with medial knee osteoarthritis

This study tested the hypothesis that patients with mild and severe medial knee osteoarthritis (OA) adopt different compensatory gait patterns to unload the deseased knee, in not only the frontal plane but also the sagittal plane. Fifteen patients with mild and 15 with severe bilateral medial knee OA, and 15 normal controls walked while the kinematic and kinetic data were measured. Compared to the normal group, both OA groups had significantly greater pelvic anterior tilt, swing-pelvis list, smaller standing knee abduction, as well as smaller standing hip flexor and knee extensor moments during stance. The severe group also had greater hip abduction, knee extension and ankle plantarflexion. The mild group successfully reduced the extensor moment and maintained normal abductor moment at the diseased knee mainly through listing and anterior tilting the pelvis. With extra compensatory changes at other joints and increased hip abductor moment, the severe group successfully reduced the knee extensor moment but failed to reduce the abductor moment. These results suggest that, apart from training of the knee muscles, training of the hip muscles and pelvic control are essential in the rehabilitative intervention of patients with knee OA, especially for more severe patients.

In vivo three-dimensional kinematics of the normal knee during active extension under unloaded and loaded conditions using single-plane fluoroscopy

Measurement of the changes of the three-dimensional (3D) motion and surface kinematics of the knee under different external loading conditions is essential for the understanding and evaluation of the function of the joint, as well as for relevant clinical applications. Knee extension exercise (KEE) has been applied extensively in the rehabilitation programs of patients with various knee disorders. This study measured the 3D knee kinematics of eight normal subjects during active knee extension for unloaded and loaded conditions using a voxel-based method for the registration of fluoroscopic images with CT bone data. The knee kinematics during unloaded conditions were found to be similar to previous findings. A mass of 5 kg at the ankle did not affect the joint angles but significantly altered the lateral contact positions during knee extension, especially at knee flexion angles higher than 75 degrees, and also reduced the asymmetry of the surface kinematics between the medial and lateral condyles. The results of the current study may be useful for knee replacement design and for developing guidelines for the use of KEEs for the rehabilitation of patients with knee disorders.

Age and height effects on the center of mass and center of pressure inclination angles during obstacle-crossing

Tripping over obstacles has been reported as one of the most frequent causes of falls in the elderly. Maintenance of the bodys balance and precise swing foot control is essential for successful obstacle-crossing. The aim of this study was thus to investigate the height and age effects on the center of mass (COM) and center of pressure (COP) inclination angles and angular velocities during obstacle-crossing. Ten healthy young and 15 healthy older adults were recruited to walk and cross obstacles of heights of 10%, 20% and 30% of their leg lengths. The COM and COP position data were calculated using data measured from a three-dimensional (3D) motion analysis system and forceplates. Smaller medial COM-COP inclination angles were found in the older group, suggesting that the neuromusculoskeletal system may have more room to control the swing foot with sufficient foot clearance. Decreased inclination angles with increasing obstacle height suggest that the subjects tended to keep their COM position close to the COP position to increase the bodys stability. Greater anterior inclination angular velocities were found in the older group to maintain the same inclination angles as the young. Not only inclination angles, but also COM-COP angular velocity, were useful for assessing ones ability to control the bodys dynamic stability.

Enhancing the examiner's resisting force improves the reliability of manual muscle strength measurements: comparison of a new device with hand-held dynamometry.

OBJECTIVE To develop and determine the reliability of a newly -designed resistance-enhanced dynamometer for muscle strength measurement, and to test the hypothesis that enhancing the examiners resisting force improves the reliability of manual muscle strength measurements. DESIGN An intra-examiner, inter-examiner, intra-session and inter-session reliability study. SUBJECTS Twenty-five men (mean age 22.5 (standard deviation (SD) 1.7) years) were tested separately by 2 examiners using the resistance-enhanced dynamometer and a traditional hand-held dynamometer for an intra- and inter-examiner reliability study. Twenty-seven volunteers (mean age 22.1 (SD 0.8) years) were tested by a female examiner using the resistance-enhanced dynamometer for an intra- and inter-session reliability study. METHODS Maximum resisting forces for the knee flexors and extensors were measured using the resistance-enhanced dynamometer and the traditional hand-held dynamometer. RESULTS The traditional hand-held dynamometer had good intra-examiner reliability (intra-class correlation coefficient (ICC) = 0.79-0.93) but poor inter-examiner reliability (ICC = 0.11-0.28). The resistance-enhanced dynamo meter had very good intra-examiner (ICC = 0.91-0.94), inter-examiner (ICC = 0.98), intra-session (ICC = 0.93-0.99) and inter-session (ICC = 0.91-0.92) reliability. The resistance-enhanced dynamometer also had better inter-examiner agreement (smallest real difference (SRD) 9-16% for resistance-enhanced dynamometer, 21-43% for traditional hand-held dynamometer). CONCLUSION The resistance-enhanced dynamometer had very good reliability. Enhancing the examiners resisting force appeared to improve the reliability of manual muscle strength measurements. The resistance-enhanced dynamometer is useful for muscle strength measurements in clinical practice.

Patients with type II diabetes mellitus display reduced toe-obstacle clearance with altered gait patterns during obstacle-crossing

Patients with type II diabetes mellitus (DM) have been reported to be at high risk of falls that may be further increased by the effects of challenging activities such as obstacle-crossing. The purpose of this study was to compare the end-point trajectory and joint kinematic and kinetic patterns of the lower extremities between healthy subjects and individuals with DM during obstacle-crossing with the leading limb. Fourteen patients with type II DM, with no to minimal peripheral neuropathy (PN), and 14 healthy controls walked and crossed obstacles of three different heights (10%, 20% and 30% of leg length) while kinematic and kinetic data were measured using a motion analysis system and two forceplates. Compared to normal, the DM group had similar walking speeds and horizontal footobstacle distances but significantly reduced leading toe-obstacle clearances, suggesting an increased risk of tripping over the obstacle. When the swing toe was above the obstacle, the DM group showed greater pelvic anterior tilt, stance ankle dorsiflexion, and smaller swing hip abduction, with reduced hip abductor moments but greater knee flexor and ankle plantarflexor and adductor moments. It is suggested that patients with type II DM, with no or minimal PN, should also be targeted for prevention of falls. Possible therapeutic interventions to decrease falls for those with DM may include strengthening of the knee flexors and ankle plantarflexor muscles, together with proprioception and balance training.

Bilateral knee osteoarthritis does not affect inter-joint coordination in older adults with gait deviations during obstacle-crossing.

Fifteen elderly subjects with bilateral medial knee osteoarthritis (OA) and 15 healthy elderly subjects walked and crossed obstacles with heights of 10%, 20%, and 30% of their leg lengths while sagittal angles and angular velocities of each joint were measured and their phase angles (phi) calculated. Continuous relative phase (CRP) were also obtained, i.e., phi(hip-knee) and phi(knee-ankle). The standard deviations of the CRP curve points were averaged to obtain deviation phase (DP) values for the stance and swing phases. Significant differences between the OA and control groups were found in several of the peak and crossing angles, and angular velocities at the knee and ankle. Both groups had similar CRP patterns, and the DP values of the hip-knee and knee-ankle CRP curves were not significantly different between the two groups. Despite significant changes in the joint kinematics, knee OA did not significantly change the way the motions of the lower limb joints are coordinated during obstacle-crossing. It appears that the OA groups adopted a particular biomechanical strategy among all possible strategies that can accommodate the OA-induced changes of the knee mechanics using unaltered inter-joint coordination control. This enabled the OA subjects to accommodate reliably the mechanical demands related to bilateral knee OA in the sagittal plane during obstacle-crossing. Maintaining normal and reliable inter-joint coordination may be considered a goal of therapeutic intervention, and the patterns and variability of inter-joint coordination can be used for the evaluation of treatment effects.

Biomechanical strategies for successful obstacle crossing with the trailing limb in older adults with medial compartment knee osteoarthritis

To investigate the biomechanical strategy adopted by older adults with medial compartment knee osteoarthritis (OA) for successful obstacle crossing with the trailing limb, and to discuss its implications for fall-prevention, 15 older adults with bilateral medial compartment knee OA and 15 healthy controls were recruited to walk and cross obstacles of heights of 10%, 20%, and 30% of their leg lengths. Kinematic and kinetic data were obtained using a three-dimensional (3D) motion analysis system and forceplates. The OA group had higher trailing toe clearance than the controls. When the trailing toe was above the obstacle, the OA group showed greater swing hip abduction, yet smaller stance hip adduction, knee flexion, and ankle eversion. They showed greater pelvic anterior tilt and toe-out angle. They also exhibited greater peak knee abductor moments during early stance and at the instant when the swing toe was above the obstacle, while a greater peak hip abductor moment was found during late stance. Smaller knee extensor, yet greater hip extensor moments, were found in the OA group throughout the stance phase. In order to achieve higher toe clearance with knee OA, particular joint kinematic and kinetic strategies have been adopted by the OA group. Weakness in the hip abductors and extensors in individuals with OA may be risk factors for tripping owing to the greater demands on these muscle groups during obstacle crossing by these individuals.

Symmetrical kinematic changes in highly functioning older patients post-stroke during obstacle-crossing

With the advances in stroke care, the number of high-functioning patients after stroke is increasing. However, existing clinical tools may not be sensitive enough to identify the residual deficits in these patients. The current study aimed to investigate the control of the pelvis, and the joints and end-point of the lower limbs in high-functioning older patients post-stroke during obstacle-crossing using motion analysis techniques. Twenty-four high-functioning older patients following unilateral stroke and fifteen healthy controls walked and crossed obstacles of three different heights. End-point variables (leading toe-clearance and trailing toe-obstacle distance) and crossing pelvic and joint angles were obtained for both limbs during leading limb crossing. Whether leading with the contralesional or ipsilesional limb, the stroke group exhibited significantly different joint kinematics from the controls mainly in the frontal and transverse planes, with greater leading toe-clearance, trailing toe-obstacle distance, and posterior pelvic tilt. None of the end-point and joint variables were significantly different between limbs. High-functioning patients post-stroke appeared to have acquired a specific symmetric kinematic strategy with increased leading toe-clearance during obstacle-crossing, most likely in order to prevent tripping. This symmetric strategy, possibly a consequence of brain reorganization, may help in performing functional activities during which symmetric performance between the contralesional and ipsilesional sides is required. Obstacle-crossing training with both limbs leading alternately may be helpful for the development of this symmetric strategy. It is suggested that computerized motion analysis of obstacle-crossing can be a sensitive assessment tool for distinguishing the motor performance between normal and high-functioning patients post-stroke.

Control of Body's Center of Mass Motion During Level Walking and Obstacle-Crossing in Older Patients with Knee Osteoarthritis

Knee osteoarthritis (OA) has been reported to affect the performance of ambulation, including unobstructed and obstructed gait. An increased risk of falling in patients with knee OA during obstaclecrossing, as opposed to unobstructed level walking, may be explained by the difference in the control of the bodys center of mass (COM) with respect to the center of pressure (COP) while trying to ensure sufficient foot clearance. The purpose of the study was to investigate the dynamic stability in patients with knee OA during level walking and obstacle-crossing. The COM-COP inclination angles and angular velocities, as well as temporal-spatial variables, from eleven patients with bilateral knee OA and eleven normal controls were obtained during level walking and obstacle-crossing using a three-dimensional motion analysis system and forceplates. Demands in the control of the COM relative to the COP were found to be greater during obstacle-crossing in both subject groups. While less stable COM control was found around the end stage of double stance phase during obstacle-crossing when compared to level walking, patients with knee OA successfully acquired strategies in the sagittal plane to maintain close-tonormal stable COM control with normal toe clearances during both level walking and obstacle-crossing. They achieved stable transitions from single limb stance (SLS) to double limb stance (DLS) through a reduced anterior inclination angle and from DLS to SLS through increased anterior angular velocity. It is suggested that assessment of the ability to control dynamic stability in patients with knee OA should consider both the positions and velocities of the COM and COP.

Immediate Effect of Lateral-Wedged Insole on Stance and Ambulation After Stroke

Chen C-H, Lin K-H, Lu T-W, Chai H-M, Chen H-L, Tang P-F, Hu M-H: Immediate effect of lateral-wedged insole on stance and ambulation after stroke. Objective:To perform kinematic and kinetic analyses on the static standing and ambulation in subjects after stroke with and without wearing a 5-degree lateral-wedged insole. Design:Ten hemiparetic individuals with unilateral stroke were recruited. Participants performed quiet stance and ambulation with no insole wedge, paretic side wedged, and nonparetic side wedged in a random order. The vertical ground reaction force and temporal-spatial parameters of gait were measured. Symmetry index was also calculated. Results:During quiet stance, the symmetry index of weight bearing improved significantly with nonparetic side-wedged (P < 0.017), but not with paretic side-wedged insoles. During ambulation, the symmetry indices of kinematic and kinetic measurements in the frontal plane were not significantly different among the three conditions. However, the contralateral knee abductor moment was significantly (P < 0.05) less than that of the nonparetic limb during nonparetic side-wedged ambulation. The ipsilateral hip and knee abductor moments were significantly (P < 0.05) less than the nonparetic limb during paretic side-wedged ambulation. Conclusions:Application of nonparetic side wedge insole can improve stance symmetry and tends to reduce the paretic knee abductor load during ambulation. The effects of paretic side-wedged insole are different. The present results provide guidelines for the placement of wedges in the shoes of individuals after stroke.