Ruoli Wang

One year follow-up after operative ankle fractures: A prospective gait analysis study with a multi-segment foot model

Ankle fractures are one of the most common lower limb traumas. Several studies reported short- and long-term post-operative results, mainly determined by radiographic and subjective functional evaluations. Three-dimensional gait analysis with a multi-segment foot model was used in the current study to quantify the inter-segment foot motions in 18 patients 1 year after surgically treated ankle fractures. Data were compared to that from gender- and age-matched healthy controls. The correlations between Olerud/Molander ankle score and kinematics were also evaluated. Patients with ankle fractures showed less plantarflexion and smaller range of motion in the injured talocrural joint, which were believed to be a sign of residual joint stiffness after surgery and immobilization. Moreover, the forefoot segment had smaller sagittal and transverse ranges of motion, less plantarflexion and the hallux segment had less dorsiflexion and smaller sagittal range of motion. The deviations found in the forefoot segment may contribute to the compensation mechanisms of the injured ankle joint. Findings of our study show that gait analysis with a multi-segment foot model provides a quantitative and objective way to perform the dynamic assessment of post-operative ankle fractures, and makes it possible to better understand not only how the injured joint is affected, but also the surrounding joints.

The effect of subtalar inversion/eversion on the dynamic function of the tibialis anterior, soleus, and gastrocnemius during the stance phase of gait.

The purpose of this study was to determine how gait deviation in one plane (i.e. excessive subtalar inversion/eversion) can affect the dynamic function of the tibialis anterior, gastrocnemius, and soleus to accelerate the subtalar, ankle, knee and hip joints, as well as the body center of mass. Induced acceleration analysis was performed based on a subject-specific three-dimensional linkage model configured by stance phase gait data and driven by one unit of muscle force. Eight healthy adult subjects were examined in gait analysis. The subtalar inversion/eversion was modeled by offsetting up to 20° from the normal subtalar angle while other configurations remained unaltered. This study showed that the gastrocnemius, soleus and tibialis anterior generally functioned as their anatomical definition in normal gait, but counterintuitive function was occasionally found in the bi-articular gastrocnemius. The plantarflexors play important roles in the body support and forward progression. Excessive subtalar eversion was found to enlarge the plantarflexors and tibialis anteriors function. Induced acceleration analysis demonstrated its ability to isolate the contributions of individual muscle to a given factor, and as a means of studying effect of pathological gait on the dynamic muscle functions.

Compensatory strategies during walking in response to excessive muscle co-contraction at the ankle joint

Excessive co-contraction causes inefficient or abnormal movement in several neuromuscular pathologies. How synergistic muscles spanning the ankle, knee and hip adapt to co-contraction of ankle muscles is not well understood. This study aimed to identify the compensation strategies required to retain normal walking with excessive antagonistic ankle muscle co-contraction. Muscle-actuated simulations of normal walking were performed to quantify compensatory mechanisms of ankle and knee muscles during stance in the presence of normal, medium and high levels of co-contraction of antagonistic pairs gastrocnemius+tibialis anterior and soleus+tibialis anterior. The study showed that if co-contraction increases, the synergistic ankle muscles can compensate; with gastrocmemius+tibialis anterior co-contraction, the soleus will increase its contribution to ankle plantarflexion acceleration. At the knee, however, almost all muscles spanning the knee and hip are involved in compensation. We also found that ankle and knee muscles alone can provide sufficient compensation at the ankle joint, but hip muscles must be involved to generate sufficient knee moment. Our findings imply that subjects with a rather high level of dorsiflexor+plantarflexor co-contraction can still perform normal walking. This also suggests that capacity of other lower limb muscles to compensate is important to retain normal walking in co-contracted persons. The compensatory mechanisms can be useful in clinical interpretation of motion analyses, when secondary muscle co-contraction or other deficits may present simultaneously in subjects with motion disorders.

Analytical decomposition can help to interpret ankle joint moment–angle relationship

Moment-angle relationship (dynamic joint stiffness)--the relationship between changes in joint moment and changes in joint angle--is useful for demonstrating interaction of kinematics and kinetics during gait. However, the individual contributors of dynamic joint stiffness are not well studied and understood, which has thus far limited its clinical application. In this study, ankle dynamic joint stiffness was analyzed and decomposed into three components in thirty able-bodied children during the stance phase of the gait. To verify the accuracy of the decomposition, the sum of decomposed components was compared to stiffness computed from experimental data, and good to very good agreement was found. Component 1, the term associated with changes in ground reaction force moment, was the dominant contribution to ankle dynamic joint stiffness. Retrospective data from eight children with juvenile idiopathic arthritis and idiopathic toe-walking was examined to explore the potential utility of analytical decomposition in pathological gait. Compared to controls, component 1 was the source of highest deviation in both pathological groups. Specifically, ankle dynamic joint stiffness differences can be further identified via two sub-components of component 1 which are based on magnitudes and rates of change of the ground reaction force and of its moment arm, and differences between the two patient groups and controls were most evident and interpretable here. Findings of the current study indicate that analytical decomposition can help identify the individual contributors to joint stiffness and clarify the sources of differences in patient groups.

Self-rated walking disability and dynamic ankle joint stiffness in children and adolescents with Juvenile Idiopathic Arthritis receiving intraarticular corticosteroid joint injections of the foot

BACKGROUND Children and adolescents with Juvenile Idiopathic Arthritis (JIA) exhibit deviations in ankle dynamic joint stiffness (DJS, or moment-angle relationship) compared to healthy peers, but the relationship between ankle DJS and self-reported walking impairments has not been studied. This secondary analysis aimed to investigate the relationship between ankle DJS and self-reported walking disability in juveniles with JIA, and to determine whether intraarticular corticosteroid foot injections (IACI) were associated with long term changes in ankle DJS. RESEARCH QUESTIONS Is ankle DJS altered in children with JIA reporting walking difficulties compared to children with JIA reporting no walking difficulties? Are IACIs associated with persistent alterations in ankle DJS? METHODS Gait dynamics (DJS), foot pain, and foot-related disability were assessed in 33 children with JIA before intraarticular corticoid foot injection (IACI), and three months after IACI. Using self-reported walking capacity scores, children were classified as either having no walking difficulties (ND) or having walking difficulties (WD). Inferential statistics were used to compare demographics, pain, impairment scores, and ankle DJS between the groups. RESULTS Before treatment, in the WD group, ankle DJS was significantly decreased both in the early rising phase (ERP = 0.03+0.02 vs. 0.05+0.02 Nm(kg*deg)- 1) and late rising phase (LRP = 0.11+0.06 vs. 0.24+0.22 Nm(kg*deg)-1) compared to the ND group. At three months, the ERP was still significantly decreased in the WD group (ERP = 0.03+0.01 vs. 0.05+0.03 Nm(kg*deg)-1). SIGNIFICANCE Among children and adolescents with JIA who reported walking difficulties prior to IACIs, alterations in DJS in early stance phase (decreased ERP) remained three months after IACI suggesting persistent gait adaptations, possibly related to pain. Pre-treatment gait analysis may aid in identifying children who will not have long term benefit from IACIs in terms of improved gait, and therefore, may be informed and have the choice to be spared the risk of side effects associated with this treatment.

The Effect of Excessive Subtalar Inversion/Eversion on the Dynamic Function of the Soleus and Gastrocnemius During the Stance Phase

The effect of excessive subtalar inversion/eversion on the dynamic function of the soleus and gastrocnemius during the stance phase