Muscle Contributions to Pre-Swing Biomechanical Tasks Influence Swing Leg Mechanics in Individuals Post-Stroke during Walking

Background Successful walking requires the execution of the pre-swing biomechanical tasks of body propulsion and leg swing initiation, which are often impaired post-stroke. While excess rectus femoris activity during swing is often associated with low knee flexion, previous work has suggested that deficits in propulsion and leg swing initiation may also contribute. The purpose of this study was to determine underlying causes of propulsion, leg swing initiation and knee flexion deficits in pre-swing and their link to stiff knee gait in stroke survivors. Methods Musculoskeletal models and forward dynamic simulations were developed for individuals post-stroke (n=15) and neurotypical participants (n=5). Linear regressions were used to evaluate the relationships between peak knee flexion, braking and propulsion symmetry, and individual muscle contributions to braking, propulsion, knee flexion in pre-swing, and leg swing initiation. Results 27% of individuals post-stroke had higher plantarflexor contributions to propulsion and 47% had higher vasti contributions to braking on their paretic leg relative to their nonparetic leg. Higher gastrocnemius contributions to propulsion were correlated to paretic propulsion symmetry (p=0.005) while soleus contributions were not. Higher vasti contributions to braking in pre-swing predicted lower knee flexion (p=0.022). The rectus femoris and iliopsoas did not directly contribute to lower knee flexion acceleration in pre-swing compared to contributions from the vasti. However, for some individuals with low knee flexion, during pre-swing the rectus femoris absorbed more power and the iliopsoas contributed less power to the paretic leg. Total muscle-tendon work done on the paretic leg in pre-swing was not correlated to knee flexion during swing. Conclusions These results emphasize the multiple causes of propulsion asymmetry in individuals post-stroke, including low plantarflexor contributions to propulsion, increased vasti contributions to braking and reliance on compensatory mechanisms. The results also show that the rectus femoris is not a major contributor to knee flexion in pre-swing, but absorbs more power from the paretic leg in pre-swing in some individuals with stiff knee gait. These results further highlight the heterogeneity of the post-stroke population and the need to identify individual causes of propulsion and knee flexion deficits to improve rehabilitation outcomes.

Does the Duncan-Ely test predict abnormal activity of the rectus femoris in stroke survivors with a stiff knee gait?

Objective: To determine the diagnostic value of the Duncan-Ely test in predicting abnormal rectus femoris activity during gait in stroke survivors walking with a stiff knee gait. Design: Cross-sectional diagnostic study. Subjects: A total of 95 patients with chronic stroke. Methods: During physical examination, the Duncan-Ely test was performed and scored. Surface electromyography of the rectus femoris was then recorded during dynamic gait. To determine the diagnostic value, the results of the Duncan-Ely test and surface electromyography recordings (gold standard) were compared. Results: The Duncan-Ely test had a sensitivity of 73%, a specificity of 29%, a positive predictive value of 60%, and a negative predictive value of 42%. The area under the curve was 0.488 ([AQ1] CI 0.355–0.621, p = 0.862), showing that the Duncan-Ely test is not better than random guessing. Conclusion: The Duncan-Ely test has no predictive value for determining abnormal activity of the rectus femoris during gait. Using this test can lead to incorrect identification of abnormal rectus femoris activity, which might hamper the selection of optimal treatment options. We recommend stopping use of the Duncan-Ely test to predict rectus femoris overactivity during swing, and instead use surface electromyography.

Self-Reported Walking Difficulty Associated with Stiff-Knee Gait in Japanese Patients with Knee Osteoarthritis: A Preliminary Cross-Sectional Study

Background: Individuals with knee osteoarthritis are restricted in their daily activity because of walking difficulty. The purpose of this investigation was to examine the association between self-reported walking difficulty and knee flexion excursion during gait in Japanese patients with knee osteoarthritis. Methods: Twenty-eight patients with knee osteoarthritis participated in this study. Knee flexion excursions in loading response and swing during gait were measured through an inertial measurement unit-based motion capture system. The walking difficulty was assessed by a subitem in the Japanese Knee Osteoarthritis Measure. Pain intensity was assessed by a visual analog scale. Characteristics and gait variables were compared between groups that were determined a priori using the results of the walking difficulty assessment. The relationship between knee flexion excursion during gait and walking difficulty were analyzed using logistic regression. Results: The participants with walking difficulty had significantly small knee flexion excursion in both loading response and swing with large pain. After controlling the effect of pain, only knee flexion excursion in the swing was significantly related to the walking difficulty. Conclusions: This study suggested that the knee flexion excursion in swing during gait is helpful for understanding the walking difficulty experienced in Japanese patients with knee osteoarthritis.

Center of Pressure Trajectory and Spatiotemporal Gait Parameters When Walking with Limited Knee Flexion

Stiff-knee, which indicates reduced range of knee flexion, may decrease gait stability. Although it is closely related to an increase in fall risk, the effect of limited knee flexion on the balance capacity during walking has not been well studied. This study aimed at examining how walking with limited knee flexion would influence the center of pressure (COP) trajectory and spatiotemporal gait parameters. Sixteen healthy young participants conducted four different walking conditions: normal walking and walking with limited knee flexion of their left knee up to 40 and 20 degrees, respectively. Results show that the participants walked significantly (p<0.05) slower with shorter stride length, wider step width, less cadence, and decreased stance phase when walking with limited knee flexion, compared to normal walking. The increase in the asymmetry and variability of the COP was also observed. It indicates that limited knee flexion during walking might affect the dynamic balance.

A comparative study of total knee arthroplasty outcome for stiff knee with or without sequential antirheumatic drug treatment

Background The aim of this study was to evaluate the influence of antirheumatic drug treatment on knee function of stiff knee patients after total knee arthroplasty (TKA). Methods Twenty-seven patients (44 knees) of active RA (rheumatoid arthritis) or AS (ankylosing spondylitis) with stiff knees were included in this study. And they were divided into two groups according to continue antirheumatic drug treatment or not after TKA: the therapeutic group (16 patients, 27 knees) and the controlled group (11 patients, 17 knees). The outcomes were assessed by Knee Society Score (KSS), Visual Analogue Scale (VAS), range of motion (ROM) (at week 6, month 6, year 1, and year 2), “Forgotten Joint” Scale (FJS), with or without crutch, satisfaction, and revision (at year 2). The knee prosthetic loosening was evaluated by the followed X-ray at each following time. Results The mean follow-up time was 51 months (34–69 months). The KSS was higher at week 6 after TKA in the therapeutic group (p < 0.05); however, the functional scores of KSS at month 6, year 1, and year 2 in the controlled group were more points improved. The therapeutic patients preferred the knee more at month 6, year 1, and year 2. The differences of KSS clinical scores (at month 6, year 1, and year 2), VAS, ROM, Crutch and FJS between the two groups were not statistically significant (p > 0.05). Conclusion For patients with stiff knees, the sequential antirheumatic drug treatment after TKA had no obvious effect on postoperative KSS, but can improve the satisfaction. Level of evidence Therapeutic level II. See Instructions for Authors for a complete description of levels of evidence.

A Comparative Study of Total Knee Arthroplasty Outcome for Stiff Knee with or without Sequential Antirheumatic Drug Treatment

BackgroundTo evaluate influence of antirheumatic drug treatment on knee function of patients with stiff knee after total knee arthroplasty (TKA). MethodsTwenty-seven patients (44 knees) of active RA (rheumatoid arthritis) or AS (ankylosing spondylitis) with stiff knee were included in this study. And they were divided into two groups according to continue antirheumatic drug treatment or not after TKA: the therapeutic group (16 patients, 27 knees) and the controlled group (11 patients, 17 knees). The outcomes were assessed by Knee Society Score (KSS), Visual Analogue Scale (VAS), range of motion (ROM) (at week 6, month 6, year 1 and year 2), “Forgotten Joint” Scale (FJS), with or without crutch, satisfaction and revision (at year 2). The knee prosthetic loosening was evaluated by the followed X-ray at each following time. ResultsThe mean follow-up time was 51 months (34-69 months). The KSS were higher at week 6 after TKA in the therapeutic group (p < 0.05), however, the functional scores of KSS at month 6, year 1 and year 2 in the controlled group were more points improved. The therapeutic patients preferred the knee more at month 6, year 1 and year 2. The differences of KSS clinical scores (at month 6, year 1 and year 2), VAS, ROM, Crutch and FJS between the two groups were not statistically significant (p＞0.05). ConclusionFor patients with stiff knees, the sequential antirheumatic drug treatment after TKA had no effect on postoperative KSS, but can improve the satisfaction.Level of evidenceTherapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.