Reliability of doming and toe flexion testing to quantify foot muscle strength.

BACKGROUND: Quantifying the strength of the intrinsic foot muscles has been a challenge for clinicians and researchers. The reliable measurement of this strength is important in order to assess weakness, which may contribute to a variety of functional issues in the foot and lower leg, including plantar fasciitis and hallux valgus. This study reports 3 novel methods for measuring foot strength - doming (previously unmeasured), hallux flexion, and flexion of the lesser toes. METHODS: Twenty-one healthy volunteers performed the strength tests during two testing sessions which occurred one to five days apart. Each participant performed each series of strength tests (doming, hallux flexion, and lesser toe flexion) four times during the first testing session (twice with each of two raters) and two times during the second testing session (once with each rater). Intra-class correlation coefficients were calculated to test for reliability for the following comparisons: between raters during the same testing session on the same day (inter-rater, intra-day, intra-session), between raters on different days (inter-rater, inter-day, inter-session), between days for the same rater (intra-rater, inter-day, inter-session), and between sessions on the same day by the same rater (intra-rater, intra-day, inter-session). RESULTS: ICCs showed good to excellent reliability for all tests between days, raters, and sessions. Average doming strength was 99.96 ± 47.04 N. Average hallux flexion strength was 65.66 ± 24.5 N. Average lateral toe flexion was 50.96 ± 22.54 N. CONCLUSIONS: These simple tests using relatively low cost equipment can be used for research or clinical purposes. If repeated testing will be conducted on the same participant, it is suggested that the same researcher or clinician perform the testing each time for optimal reliability.

Biomechanical analysis of gait termination in 11-17year old youth at preferred and fast walking speeds.

In populations where walking and/or stopping can be difficult, such as in children with cerebral palsy, the ability to quickly stop walking may be beyond the child's capabilities. Gait termination may be improved with physical therapy. However, without a greater understanding of the mechanical requirements of this skill, treatment planning is difficult. The purpose of this study was to understand how healthy children successfully terminate gait in one step when walking quickly, which can be challenging even for healthy children. Lower extremity kinematic and kinetic data were collected from 15 youth as they performed walking, planned, and unplanned stopping tasks. Each stopping task was performed as the subject walked at his/her preferred speed and a fast speed. The most significant changes in mechanics between speed conditions (preferred and fast) of the same stopping task were greater knee flexion angles (unplanned: +16.49±0.54°, p=0.00; planned: +15.75±1.1°, p=0.00) and knee extension moments (unplanned: +0.67±0.02N/kgm, p=0.00; planned: +0.57±0.23N/kgm, p=0.00) at faster speeds. The extra range of motion in the joints and extra muscle strength required to maintain the stopping position suggests that stretching and strengthening the muscles surrounding the joints of the lower extremity, particularly the knee, may be a useful intervention.

Automated event detection algorithms in pathological gait.

Accurate automated event detection is important in increasing the efficiency and utility of instrumented gait analysis. Published automated event detection algorithms, however, have had limited testing on pathological populations, particularly those where force measurements are not available or reliable. In this study we first postulated robust definitions of gait events that were subsequently used to compare kinematic based event detection algorithms across difficult pathologies. We hypothesized that algorithm accuracy would vary by gait pattern, and that accurate event detection could be accomplished by first visually classifying the gait pattern, and subsequently choosing the most appropriate algorithm. Nine published kinematic event detection algorithms were applied to an existing instrumented pediatric gait database (primarily cerebral palsy pathologies), that were categorized into 4 visually distinct gait patterns. More than 750 total events were manually rated and these events were used as a gold standard for comparison to each algorithm. Results suggested that for foot strike events, algorithm choice was dependent on whether the foot's motion in terminal swing was more horizontal or vertical. For horizontal foot motion in swing, algorithms that used horizontal position, resultant sagittal plane velocity, or horizontal acceleration signals were most robust; while for vertical foot motion, resultant sagittal velocity or vertical acceleration excelled. For toe off events, horizontal position or resultant sagittal plane velocity performed the best across all groups. We also tuned the resultant sagittal plane velocity signal to walking speed to create an algorithm that can be used for all groups and in real time.

Kinematic and kinetic analysis of planned and unplanned gait termination in children.

Gait termination is a task which requires people to alter momentum and stabilize the body. To date, many of the kinematic and kinetic characteristics of gait termination have not been reported, making it difficult for clinicians to design interventions to improve the ability to terminate gait quickly and efficiently. Therefore, the purpose of this study was to describe the lower body mechanics of healthy children as they performed walking trials, planned stopping trials, and unplanned stopping trials. Kinematic and kinetic data were collected from 15 healthy children between the ages of 11 and 17 years (14.3±2.1 years). The timing and magnitude of peak sagittal plane joint angles and moments were compared across the three conditions for the leg that led the stop step. Most differences were found when comparing unplanned stopping to both walking and planned stopping. During unplanned stopping, most subjects used either a hip/knee extension strategy or hip/knee flexion strategy to stabilize and perform the stopping task. The magnitudes of the peak hip extension moment and peak knee flexion angle were significantly greater, while the peak plantarflexion moment was significantly smaller during unplanned stopping than walking and planned stopping. The peak plantarflexion moment occurred significantly earlier during the stop stance phase of planned and unplanned stopping than during walking. This suggests that the ability to create sufficient joint moments in a short period of time is essential to be able to stop quickly and safely. Therefore, possible treatments/interventions should focus on ensuring that patients have appropriate strength, power, and range of motion.

Real-time feedback as a method of monitoring walking velocity during gait analysis.

When quantifying the mechanics of gait, it is important to ensure that subjects maintain a consistent walking velocity during gait analysis trials. Most methods of measuring walking velocity do not produce data until after the subject has completed the trial. This often results in discarding completed trials from analysis because the subject's velocity was not within an acceptable range. Real-time feedback of position data can be used to help subjects adjust their walking velocity during the trial, when necessary. Results from 14 subjects who participated in gait analysis using real-time feedback to monitor their walking velocity show that they were able to stay within an acceptable range of their target walking velocities (each subject's preferred velocity and 150% of their preferred velocity) during 90% and 80% of trials, respectively. This method allows for accurate and efficient data collections without the use of additional equipment.