Impaired Limb Shortening following Stroke: What’s in a Name?

Background

Difficulty advancing the paretic limb during the swing phase of gait is a prominent manifestation of walking dysfunction following stroke. This clinically observable sign, frequently referred to as ‘foot drop’, ostensibly results from dorsiflexor weakness.

Objective

Here we investigated the extent to which hip, knee, and ankle motions contribute to impaired paretic limb advancement. We hypothesized that neither: 1) minimal toe clearance and maximal limb shortening during swing nor, 2) the pattern of multiple joint contributions to toe clearance and limb shortening would differ between post-stroke and non-disabled control groups.

Methods

We studied 16 individuals post-stroke during overground walking at self-selected speed and nine non-disabled controls who walked at matched speeds using 3D motion analysis.

Results

No differences were detected with respect to the ankle dorsiflexion contribution to toe clearance post-stroke. Rather, hip flexion had a greater relative influence, while the knee flexion influence on producing toe clearance was reduced.

Conclusions

Similarity in the ankle dorsiflexion, but differences in the hip and knee, contributions to toe clearance between groups argues strongly against dorsiflexion dysfunction as the fundamental impairment of limb advancement post-stroke. Marked reversal in the roles of hip and knee flexion indicates disruption of inter-joint coordination, which most likely results from impairment of the dynamic contribution to knee flexion by the gastrocnemius muscle in preparation for swing. These findings suggest the need to reconsider the notion of foot drop in persons post-stroke. Redirecting the focus of rehabilitation and restoration of hemiparetic walking dysfunction appropriately, towards contributory neuromechanical impairments, will improve outcomes and reduce disability.     

What’s in a loop?

DNAs and proteins are major classes of biomolecules that differ in many aspects. However, a considerable number of their members also share a common architectural feature that enables the assembly of multi-protein complexes and thereby permits the effective processing of signals: loop structures of substantial sizes. Here we briefly review a few representative examples and suggest a functional classification of different types of loop structures. In proteins, these loops occur in protein regions classified as intrinsically disordered. Studying such loops, their binders and their interactions with other loops should reveal much about cellular information computation and signaling network architectures. It is also expected to provide critical information for synthetic biologists and bioengineers.     

What Explains Differences in Men’s and Women’s Production?

Researchers commonly use long-term average production inequalities to characterize cross-cultural patterns in foraging divisions of labor, but little is known about how the strategies of individuals shape such inequalities. Here, we explore the factors that lead to daily variation in how much men produce relative to women among Martu, contemporary foragers of the Western Desert of Australia. We analyze variation in foraging decisions on temporary foraging camps and find that the percentage of total camp production provided by each gender varies primarily as a function of men’s average bout successes with large, mobile prey. When men target large prey, either their success leads to a large proportional contribution to the daily harvest, or their failure results in no contribution. When both men and women target small reliable prey, production inequalities by gender are minimized. These results suggest that production inequalities among Martu emerge from stochastic variation in men’s foraging success on large prey measured against the backdrop of women’s consistent production of small, low-variance resources.

What’s New?

What's New?

What’s New?     

What’s New?

What's New

What’s New?