Giving Way Event During a Combined Stepping and Crossover Cutting Task in an individual with Anterior Cruciate Ligament Deficiency

Study Design: Case study. Objective: To compare knee kinematics and moments of nongiving way trials to a giving way trial during a combined stepping and crossover cutting activity. Background: The knee kinematics and moments associated with giving way episodes sugge motor control strategies that lead to instability and recovery of stability during movement. Methods and Measures: A 27-year-old woman with anterior cruciate ligament deficiency reported giving way while performing a combined stepping and crossover cutting activity. P motion analysis system recorded motion of the pelvis, femur, tibia, and foot using 3 infrarec emitting diodes placed on each segment at 60 Hz. Force plate recordings at 300 Hz were combined with limb inertial properties and position data to estimate net knee joint moments. The stance time, foot progression angle, and cutting angle were also included to evaluate performance between trials. Results: Knee internal rotation during the giving way trial increased 3.2\u27 at 54% of stance relative to the nongiving way trials. Knee flexion during the giving way trial increased to 33.1 at 66% of stance, and the knee moment switched from a nominal flexor moment to 2 knee extensor moment at 64% of stance. The knee abductor moment and external rotation moment during the giving way trial deviated in early stance. Conclusions: The observed response to the giving way event suggests that increasing knee flexion may enhance knee stability for this subject. The transverse and frontal plane moments appear important in contributing to the giving way event. Further research that assists clinicians in understanding how interventions can impact control of movements in these planes is necessary

Validity and Comparisons of Tibiofemoral Angles and Translations using a New Femoral Tracking Device (FTD) during Walking

First, this study compares tibiofemoral motion during walking using a new femoral tracking device (FTD) and bone mounted markers in a single subject (n=1). The results suggest errors ofn=13). The results suggest similar tibiofemoral angles in the sagittal and frontal planes using the two methods (average root mean square (RMS) differences

Self-Reported Giving-Way Episode During a Stepping-Down Task: Case Report of a Subject With an ACL-Deficient Knee

Study Design: Case report. Objective: To describe the knee kinematics and moments of a giving-way trial of a subject with an anterior-cruciate-ligament– (ACL) deficient knee relative to his non–giving-way trials and to healthy subjects during a step-down task. Background: Episodes of giving way are believed to damage joint structures, therefore treatments aim to prevent giving-way episodes, yet few studies document giving-way events. Methods: The giving-way trial experienced by a 32-year-old male subject with ACL deficiency during a step-down task was compared to his non–giving-way trials (n = 5) and data from healthy subjects (n = 20). Position data collected at 60 Hz were combined with anthropometric data and ground reaction force data collected at 300 Hz to estimate knee displacement and 3-dimensional angles and net joint moments. Results: The knee joint displacement was higher during the giving-way trial: from 4% to 32% of stance, reaching 9.0 mm at 18% of stance as compared to 1.6 ± 0.7 mm for the non–giving-way trials. After 4% of stance, the knee flexion angle of the giving-way trial was 6.6° higher than the non–giving-way trials and was associated with a higher knee extension moment. The knee frontal plane moment was near neutral during early stance of the giving-way trial in contrast to the non-giving way and healthy subjects which demonstrated a knee abduction moment. Conclusions: The response of this subject to the giving-way event suggests that higher knee flexion angles may enhance knee stability and, in reaction to the giving-way event, that knee extension moment may increase

Relationship Between Static Mobility of the First Ray and First Ray, Midfoot, and Hindfoot Motion During Gait

The relationship between a static measure of dorsal first ray mobility and dynamic motion of the first ray, midfoot, and hindfoot during the stance phase of walking was investigated in healthy, asymptomatic subjects who represented the spectrum of static flexibility. Static first ray mobility of 15 subjects was measured by a load cell device and ranged from stiff (3.1 mm) to lax (8.0 mm). Using three-dimensional motion analysis, mean first ray dorsiflexion/eversion and mid-/hindfoot eversion peak motion, time-to-peak, and eversion excursion were evaluated. Subjects with greater static dorsal mobility of the first ray demonstrated significantly greater time-topeak hindfoot eversion and eversion excursion (p \u3c .01), and midfoot peak eversion and eversion excursion (p \u3c .01). No significant association was found between static first ray mobility and first ray motion during gait. This research provides evidence that the dynamic response of the foot may modulate the consequences of first ray mobility and that compensory strategies are most effective when static measures of dorsal mobility are most extreme

‘Dominant ethnicity’ and the ‘ethnic-civic’ dichotomy in the work of A. D. Smith

This article considers the way in which the work of Anthony Smith has helped to structure debates surrounding the role of ethnicity in present-day nations. Two major lines of enquiry are evident here. First, the contemporary role of dominant ethnic groups within 'their' nations and second, the interplay between ethnic and civic elements in nationalist argument. The two processes are related, but maintain elements of distinctiveness. Smith's major contribution to the dominant ethnicity debate has been to disembed ethnicity from the ideologically-charged and/or anglo-centric discourse of ethnic relations and to place it in historical context, thereby opening up space for dominant group ethnicity to be considered as a distinct phenomenon. This said, Smith's work does not adequately account for the vicissitudes of dominant ethnicity in the contemporary West. Building on the classical works of Hans Kohn and Friedrich Meinecke, Anthony Smith has also made a seminal contribution to the debate on civic and ethnic forms of national identity and nationalist ideology. As well as freeing this debate from the strong normative overtones which it has often carried, he has continued to insist that the terms civic and ethnic should be treated as an ideal-typical distinction rather than a scheme of classification

Associations of knee angles, moments and function among subjects that are healthy and anterior cruciate ligament deficient (ACLD) during straight ahead and crossover cutting activities

The objective of this study was to compare knee angles and moments of healthy subjects (n=20) and subjects that were anterior cruciate ligament deficient (ACLD) (n=16) during stepping and crossover cutting activities. Subjects that were ACLD were separated into high (n=7) and low (n=9) functioning groups based on knee functional ratings. Knee angles and moments were estimated using three dimensional motion tracking and force plate data. The results suggest that knee angle and moment data were associated with level of functioning of ACLD subjects. Primarily knee frontal and transverse plane moments distinguished the stepping and crossover cut activities. Only some of the findings for the ACLD group were attributed to increasing knee stability. © 2002 Elsevier Science B.V. All rights reserved

Validity and comparisons of tibiofemoral orientations and displacement using a femoral tracking device during early to mid stance of walking

First, this study compares tibiofemoral motion during walking using a new femoral tracking device (FTD) and bone mounted markers in a single subject (n=1). The results suggest errors of \u3c3° in tibiofemoral angles using the FTD method over the first 85% of stance. Second, this study compares tibiofemoral angles and displacement during walking using the FTD method and a modified Helen Hayes method to track the femur in 13 subjects (n=13). The results suggest similar tibiofemoral angles in the sagittal and frontal planes using the two methods (average root mean square (RMS) differences \u3c3.6±1.5°), and a large decrease in the transverse plane angles (average RMS differences=6.5±1.9°) and estimates of tibiofemoral displacement (P\u3c0.05) using the FTD method. The FTD method presents a practical alternative to recording tibiofemoral transverse plane angles and displacement over the first 85% of stance. © 2003 Elsevier B.V. All rights reserved