Heel Contact Phase Research Articles

Gait Asymmetry: Factors Influencing Slip Severity and Tendency among Older adults

Research on the relationship between gait asymmetry and the likelihood of slips are not clear, especially, for older adults. The present study evaluated the gait asymmetry among older adults and, further, evaluated effects of gait asymmetry on the likelihood of slips. Eighteen older adults (65 and older) participated in the study. HCV, horizontal force, and RCOF measured at non-dominant leg during heel contact phase of gait cycle were significantly higher than those at dominant leg. The results indicated that the likelihood of slips could increase when transitioning the whole body center-of-mass with left leg contacted on the ground while right leg was in swing phase. The results indicated that gait asymmetry or limb dominance could contribute to increasing the likelihood of slips.

Relationship between hamstring activation rate and heel contact velocity: Factors influencing age-related slip-induced falls

The purpose of this research was to determine whether a decreased hamstring activation rate among the elderly is responsible for a higher horizontal heel contact velocity and increased likelihood of slip-induced falls compared to their younger counterparts. Twenty-eight subjects from two age groups (14 young and 14 old) walked across a linear walking track with embedded force platforms while wearing a fall arresting harness attached to an overhead arresting rig for safety. In order to obtain realistic unexpected slip-induced fall data, a soapy vinyl floor surface was hidden from the subjects and unexpectedly introduced. Synchronized kinematics, kinetic and electromyography (EMG) analyses during the heel contact phase of the gait cycle while walking over slippery and non-slippery floor surfaces were examined in the study. Normalized EMG data were examined in terms of hamstring activation rate and evaluated with heel contact velocity and friction demand characteristic (as measured by peak required coefficient of friction (RCOF)) on the dry vinyl floor surface. Furthermore, slip parameters (i.e. slip distances and slipping velocity) were assessed on the soapy vinyl floor surface. The results indicated that younger adults' hamstring activation rate was higher than older adults, whereas younger adults' heel contact velocity was not different from older adults. These results suggested that heel contact velocity in younger adults was sufficiently reduced before the heel contact phase of the gait cycle. This could be due to the outcome of higher hamstring activation rate in younger adults in comparison to older adults. However, lower friction demand (peak RCOF), shorter slip distances, slower peak sliding heel velocity and more falls among older adults suggested that the slip initiation characteristics were not the only factors contributing to slip-induced falls among the elderly.

Early diagnosis of coxarthrosis (in-shoe plantar pressure measurements)

INTRODUCTION:: Plantar pressure measurement during walking adds dynamic functional data to evaluation of gait disorders of teenagers with coxarthrosis. The duration of the complete gait cycle, its phases (stance and swing phase for right and left feet, double support) and phases of roll-over process are found useful in many clinical applications. METHODS:: In-shoe measurements were completed with Pedar system (99 element capacitive insoles from Novel, Munich, Germany) for 38 teenagers from military school (controls) and 29 teenagers with coxarthrosis. The data from 3 - 5 trials for each subject were collected. The distance was about 10 m, no requirements to the speed and step length were established. Special software was developed. RESULTS:: Time parameters for the complete gait cycle, its phases, phases of roll-over-process were calculated both for the controls and the teenagers with coxarthrosis It was found that stance phase and heel contact phase are decreased for the teenagers with coxarthrosis. DISCUSSION:: Decrease of stance phase, insufficient loading of the heel and decrease of heel contact time are a result of attempts to compensate the painfulness in the hip joint during walking. CONCLUSION:: Time parameters of the complete gait cycle and its phases may be useful in early diagnosis of coxarthrosis and evaluation of efficiency of the treatment.

Movement of the tibial end in a PTB prosthesis socket

To investigate the movement of the tibial end in the sagittal plane in the PTB prosthetic socket during a gait cycle, 7 patients with a median age of 72 years were examined using X-ray technique. The gait cycle was reduced to four different static positions: heel contact, midstance, push-off and swing phase. The mean value of tibial movement in the socket in the anteroposterior direction was 2.2 cm, in proximodistal direction 2.8 cm, and the total sagittal movement during the whole gait cycle was 7.5 cm. The results indicate that one factor affecting the magnitude of the movement was the prestretching of soft tissues. All the patients who experienced a good prosthetic fitting had their soft tissues prestretched. The extreme dorsal and proximal positions of the tibial end during the gait cycle was in the swing phase position. The extreme distal position occurred somewhere between mid-stance and push-off. The extreme anterior position of the tibial end was seen during heel contact. This study has shown the magnitude of the movements in a PTB socket during a simulated gait cycle. The study has given hints on factors affecting prosthetic fitting, and further research within this field might provide indications of how to optimise socket shape to give maximal patient comfort.