Dataset Information

Measurement of paretic-lower-extremity loading and weight transfer after stroke.

ABSTRACT:

Background

Weight bearing through, or "loading" of, the paretic lower extremity and transfer of weight from one lower extremity to the other are important impairment-level goals of stroke rehabilitation. Improvements in these limb-loading and weight-transfer abilities have been shown to relate to improved performance of many functional activities. Unfortunately, valid and practical clinical measures of paretic-lower-extremity loading and weight transfer have not been identified.

Objective

The purpose of this study was to assess convergent validity of the Step Test (ST) and the knee extension component of the Upright Motor Control Test (UMCe) as measures of paretic-limb loading and of the Repetitive Reach Test (RR) as a measure of weight transfer in the first 6 months after stroke.

Design

This was a prospective cohort study of 33 adults with lower-extremity motor impairment following unilateral, noncerebellar stroke. Participants were tested one time per month from 1 to 6 months poststroke.

Results

Scores on the ST (performed with the nonparetic leg as the stepping leg) and UMCe were positively correlated with peak vertical ground reaction forces (GRFs) beneath the paretic limb during functional tasks (R(2)=.35-.76 for the ST, pseudo R(2)=.21-.34 for the UMCe). Scores on the RR were positively correlated with change in vertical GRF beneath the paretic limb during the diagonal reach task (R(2)=.45) and with weight-transfer time during stepping with the nonparetic limb (R(2)=.15).

Conclusions

The ST, performed with the nonparetic leg as the stepping leg, is a valid measure of paretic-limb loading during stroke recovery. Of the clinical measures tested, the ST correlated most strongly with the force platform measures.

SUBMITTER: Mercer VS

PROVIDER: S-EPMC2704028 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Publications

Measurement of paretic-lower-extremity loading and weight transfer after stroke.

Mercer Vicki Stemmons VS Freburger Janet Kues JK Chang Shuo-Hsiu SH Purser Jama L JL

Physical therapy 20090521 7

<h4>Background</h4>Weight bearing through, or "loading" of, the paretic lower extremity and transfer of weight from one lower extremity to the other are important impairment-level goals of stroke rehabilitation. Improvements in these limb-loading and weight-transfer abilities have been shown to relate to improved performance of many functional activities. Unfortunately, valid and practical clinical measures of paretic-lower-extremity loading and weight transfer have not been identified.<h4>Objec ...[more]

PMID: 19465370

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Project description:BackgroundThe ability to measure joint kinematics in natural environments over long durations using inertial measurement units (IMUs) could enable at-home monitoring and personalized treatment of neurological and musculoskeletal disorders. However, drift, or the accumulation of error over time, inhibits the accurate measurement of movement over long durations. We sought to develop an open-source workflow to estimate lower extremity joint kinematics from IMU data that was accurate and capable of assessing and mitigating drift.MethodsWe computed IMU-based estimates of kinematics using sensor fusion and an inverse kinematics approach with a constrained biomechanical model. We measured kinematics for 11 subjects as they performed two 10-min trials: walking and a repeated sequence of varied lower-extremity movements. To validate the approach, we compared the joint angles computed with IMU orientations to the joint angles computed from optical motion capture using root mean square (RMS) difference and Pearson correlations, and estimated drift using a linear regression on each subject's RMS differences over time.ResultsIMU-based kinematic estimates agreed with optical motion capture; median RMS differences over all subjects and all minutes were between 3 and 6 degrees for all joint angles except hip rotation and correlation coefficients were moderate to strong (r = 0.60-0.87). We observed minimal drift in the RMS differences over 10 min; the average slopes of the linear fits to these data were near zero (- 0.14-0.17 deg/min).ConclusionsOur workflow produced joint kinematics consistent with those estimated by optical motion capture, and could mitigate kinematic drift even in the trials of continuous walking without rest, which may obviate the need for explicit sensor recalibration (e.g. sitting or standing still for a few seconds or zero-velocity updates) used in current drift-mitigation approaches when studying similar activities. This could enable long-duration measurements, bringing the field one step closer to estimating kinematics in natural environments.

Project description:In hemiplegic gait the paretic lower limb provides less muscle power and shows a briefer stance compared with the unaffected limb. Yet, a longer stance and a higher power can be obtained from the paretic lower limb if gait speed is increased. This supports the existence of a 'learned non-use' phenomenon, similar to that underlying some asymmetric impairments of the motion of the eyes and of the upper limbs. Crouch gait (CG) (bent-hip bent-knee, about 30° minimum knee flexion) might be an effective form of 'forced-use' treatment of the paretic lower limb. It is not known whether it also stimulates a more symmetric muscle power output. Gait analysis on a force treadmill was carried out in 12 healthy adults and seven hemiplegic patients (1-127 months after stroke, median: 1.6). Speed was imposed at 0.3 m/s. Step length and single and double stance times, sagittal joint rotations, peak positive power, and work in extension of the hip, knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from extensor muscles during the generation of power were measured on either side during both erect and crouch walking. Significance was set at P less than 0.05; corrections for multiplicity were applied. Patients, compared with healthy controls, adopted in both gait modalities and on both sides a shorter step length (61-84%) as well as a shorter stance (76-90%) and swing (63-83%) time. As a rule, they also provided a higher muscular work (median: 137%, range: 77-250%) paralleled by a greater sEMG area (median: 174%, range: 75-185%). In erect gait, the generation of peak extensor power across hip, knee, and ankle joints was in general lower (83-90%) from the paretic limb and higher (98-165%) from the unaffected limb compared with control values. In CG, peak power generation across the three lower limb joints was invariably higher in hemiparetic patients: 107-177% from the paretic limb and 114-231% from the unaffected limb. When gait shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%, 56 to 72%, 68 to 91%, and 67 to 93%, respectively. CG appears to be an effective form of forced-use exercise eliciting more power and work from the paretic lower limb muscles sustained by a greater neural drive. It also seems effective in forcing a more symmetric power and work from the hip extensor muscles, but neither from the knee nor the ankle.

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Dataset Information

Measurement of paretic-lower-extremity loading and weight transfer after stroke.

Background

Objective

Design

Results

Conclusions

Publications

Measurement of paretic-lower-extremity loading and weight transfer after stroke.

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