Influence de la vitesse et de l’âge sur la variabilité intrasujet des forces de réaction et des paramètres spatiotemporels de la marche de l’enfant sain

Arthroscopic synovectomy in the treatment of functional ankle instability: outcomes and gait analysis

BACKGROUND

Natural consequence of repetitive ankle sprains is the chronic ankle instability. Objective of this study was to clarify the gait patterns of functional ankle instability (FAI) patients after arthroscopic synovectomy, but also assessment of postoperative recovery.

PATIENTS AND METHODS

Arthroscopic synovectomy was performed to 14 FAI patients with history of unilateral repetitive ankle sprains, pain, and subjective sensation of instability. At a mean 54 months of follow-up (27-84), clinical assessment was conducted with respect to pain, number of ankle sprains, and American Orthopaedics Foot and Ankle Society (AOFAS) scores. Gait analysis was conducted to determine the temporospatial, kinetic and kinematic parameters at the last follow-up.

RESULTS

Mean AOFAS scores increased from 68 (range 55-75) to 89 (range 77-100) points (P < 0.01). Mean ankle sprains was 13 in a period of 23 (range 14-48) months (0.58 per month) and decreased to three sprains in a mean time period of 54 months (0.053 per month) (P < 0.01). Mean preoperative and postoperative VAS scores were 8.0 and 2.9, respectively (P < 0.01). During gait analysis, no significant differences were found in ankle joint, including foot progression angles, ankle dorsi-plantar flexion degrees and ground reaction forces (P > 0.01). Among temporospatial parameters, only double support time showed a significant difference (P < 0.01). All patients were satisfied from the procedure and returned to their previous activity level.

CONCLUSION

Improved long-term clinical results and scores were obtained in our patient group when compared with the preoperative scores. Also, three-dimensional gait analysis showed that the involved ankles demonstrate similar gait patterns to the uninvolved ankles in patients with FAI.

Spatio-temporal gait analysis in children with cerebral palsy using, foot-worn inertial sensors

A child's natural gait pattern may be affected by the gait laboratory environment. Wearable devices using body-worn sensors have been developed for gait analysis. The purpose of this study was to validate and explore the use of foot-worn inertial sensors for the measurement of selected spatio-temporal parameters, based on the 3D foot trajectory, in independently walking children with cerebral palsy (CP). We performed a case control study with 14 children with CP aged 6-15 years old and 15 age-matched controls. Accuracy and precision of the foot-worn device were measured using an optical motion capture system as the reference system. Mean accuracy ± precision for both groups was 3.4 ± 4.6 cm for stride length, 4.3 ± 4.2 cm/s for speed and 0.5 ± 2.9° for strike angle. Longer stance and shorter swing phases with an increase in double support were observed in children with CP (p=0.001). Stride length, speed and peak angular velocity during swing were decreased in paretic limbs, with significant differences in strike and lift-off angles. Children with cerebral palsy showed significantly higher inter-stride variability (measured by their coefficient of variation) for speed, stride length, swing and stance. During turning trajectories speed and stride length decreased significantly (p<0.01) for both groups, whereas stance increased significantly (p<0.01) in CP children only. Foot-worn inertial sensors allowed us to analyze gait spatiotemporal data outside a laboratory environment with good accuracy and precision and congruent results with what is known of gait variations during linear walking in children with CP.

Gait patterns comparison of children with Duchenne muscular dystrophy to those of control subjects considering the effect of gait velocity

3D analysis of the gait of children with Duchenne muscular dystrophy (DMD) was the topic of only a few studies and none of these considered the effect of gait velocity on the gait parameters of children with DMD. Gait parameters of 11 children with DMD were compared to those of 14 control children while considering the effect of gait velocity using 3D biomechanical analysis. Kinematic and kinetic gait parameters were measured using an Optotrak motion analysis system and AMTI force plates embedded in the floor. The data profiles of children with DMD walking at natural gait velocity were compared to those of the control children who walked at both natural and slow gait velocities. When both groups walked at similar velocity, children with DMD had higher cadence and shorter step length. They demonstrated a lower hip extension moment as well as a minimal or absent knee extension moment. At the ankle, a dorsiflexion moment was absent at heel strike due to the anterior location of the center of pressure. The magnitude of the medio-lateral ground reaction force was higher in children with DMD. Despite this increase, the hip abductor moment was lower. Hip power generation was also observed at the mid-stance in DMD children. These results suggest that most of the modifications observed are strategies used by children with DMD to cope with possible muscle weakness in order to provide support, propulsion and balance of the body during gait.

Understanding the complexity of human gait dynamics

Time series of human gait stride intervals exhibit fractal and multifractal properties under several conditions. Records from subjects walking at normal, slow, and fast pace speed are analyzed to determine changes in the fractal scalings as a function of the stress condition of the system. Records from subjects with different age from children to elderly and patients suffering from neurodegenerative disease are analyzed to determine changes in the fractal scalings as a function of the physical maturation or degeneration of the system. A supercentral pattern generator model is presented to simulate the above two properties that are typically found in dynamical network performance: that is, how a dynamical network responds to stress and to evolution.

The effect of pedometer position and normal gait asymmetry on step count accuracy

Manufacturers of pedometers recommend wearing a pedometer on the midline of the right thigh and this recommendation is used in research. However, there is conflicting evidence regarding the effect of pedometer position on accuracy. The purpose of this study was to systematically evaluate the effect of pedometer position on accuracy for 3 modes of gait. The Yamax SW200 pedometer was evaluated in 20 subjects in 5 different positions simultaneously: left mid-axillary, left mid-thigh, umbilical, right mid-thigh, and right mid-axillary. Each subject was asked to walk on a treadmill (54, 80, and 107 m·min–1), to walk overground (slow, preferred, and fast speeds), and to ascend and descend stairs. Pedometer steps were recorded and compared with actual steps observed. Using the same protocol, instantaneous triaxial accelerometry was used to explain position-dependent differences in accuracy. At slow speeds, the left mid-axillary position demonstrated the lowest net mean (±SD) error across all modes of gait (7.7% (±11.6%%) overground; –0.6% (±2.2%) stairs). The right mid-thigh position had significantly (p < 0.01) higher error for treadmill (18.1% (±17.3%)), overground (12.9% (±15.2%)), and stairs (2.9% (±3.9%)). Pedometer position dependent error was demonstrated, with the left mid-axillary position superior to the recommended position of right mid-thigh. The greater accuracy on the left side was wholly explained by gait asymmetry evident in step-induced accelerations recorded at right and left pedometer positions. A model of absolute error based on the ratio of steps at different gait speeds was generated to demonstrate the importance of this finding in pedometer-based lifestyle intervention studies.