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Biomedical subjects

J A Harder

Publications and source records attributed to J A Harder.

25 records · Page 2Linked to original sources
PubMed1992

Center of mass location and segment angular orientation of below-knee-amputee and able-bodied children during walking.

This investigation compared the center of mass (COM) locations and segment angular orientations of the gait of below-knee-amputee (BKA) children to those of able-bodied (AB) children. Eleven AB children (mean age, 8.4 years) and three BKA children (mean age, 7.5 years) volunteered to participate as subjects. Film data (100 frames per second) of a typical walking stride, were collected for the children during four experimental sessions held at six-month intervals. Two 16mm cameras were used to obtain frontal and lateral views of the subjects. The same approximate rate of walking (1.2m/s +/- 10%) was enforced for all testing sessions and at least three trials of data were collected for each subject during each session. Segmental endpoints of each subject from the film of each camera were digitized and the direct linear transformation (DLT) method was used to obtain three-dimensional segmental location-time data for a complete stride. These data were then used to determine whole body COM locations and angular orientations for the segments. Discrete values describing normalized locations at touchdown, midsupport, and takeoff were determined for whole body COM and the angular orientation of the trunk, thighs, and legs. In the sagittal plane the COM was lower and more anterior for the BKA children when compared to that of the AB children. This was primarily due to the greater forward flexion of the trunk.(ABSTRACT TRUNCATED AT 250 WORDS)

Amputees↗
PubMed1991

Lower limb intersegmental forces for below-knee amputee children during standing.

The purpose of this investigation was to compare intersegmental knee and hip forces for below-knee amputee (BKA) and able-bodied children during standing. Three unilateral BKA children and 10 able-bodied children (7-9 years) were tested on four separate occasions at six month intervals. Three trials of external force and spatial data during standing were collected from each subject for each session. These data were utilised to determine the intersegmental forces at the knees and hips of the children using a static force analysis. Results indicated that in some instances the intersegmental forces for the BKA children were significantly greater than those of the able-bodied children and in other instances significantly lower (p less than 0.05). In all cases, however, the values were substantially less than corresponding values for walking and running. The effects of the forces upon spatial orientations indicated significant differences between the two groups of children. The frontal plane prosthetic knee angle, the sagittal plane prosthetic and non-prosthetic knee angles, and the sagittal plane trunk angle were all greater for the BKA children when compared to able-bodied children. These differences may be the result of the anatomical structure of the amputee and/or the construction of the prosthesis.

Amputation, Surgical↗
PubMed1991

External loading comparisons between able-bodied and below-knee-amputee children during walking.

The purpose of this investigation was to determine external loading variables that could describe any statistically significant differences between the limbs of below-knee-amputee (BKA) and able-bodied children. Eleven able-bodied children and four BKA children volunteered to participate in this investigation. Force platform data were collected for two consecutive foot falls during two experimental sessions. Significant external load differences existed between the prosthetic limbs and nonprosthetic limbs of BKA children and between limbs of the BKA and able-bodied children. The prosthetic limb generally displayed a subordinate role when compared to nonprosthetic and normal limbs. The nonprosthetic limbs displayed a dominant role when compared to the other limbs. These external loading characteristics of the prosthetic and nonprosthetic limbs may be a logical consequence of the morphologic and functional differences that exist between the groups. It was concluded that as long as the prosthetic limb functions differently from a normal limb, BKA children may have a difficult time walking the same as able-bodied children. It would appear to be advantageous to determine the most appropriate gait pattern for BKA children, given the influence of such factors as prosthetic design, construction, and alignment, rehabilitation, and joint loading.

Adolescent↗
PubMed1989

Standing pressure distribution for normal and below-knee amputee children.

Below-knee (BK) amputee children have a different morphology from normal children and amputees may thus have atypical limb loading during standing. The purpose of this investigation was to examine differences in standing ground-shoe pressure distribution between BK and normal children. A pressure plate was used to measure the ground-shoe weight distribution of three BK children and ten normal children during standing. Results indicated that the weight distribution between prosthetic and non-prosthetic limbs of BK children was not significantly different from the feet of normal children. The anterior-posterior weight distribution for the prosthetic and non-prosthetic feet was significantly different from that of the normal children. Further quantification of weight distribution and analysis of more subjects is necessary to determine the benefits, detriments, or irrelevance of these results.

Amputation, Surgical↗
PubMedDate not supplied

Normative ground reaction force data for able-bodied and below-knee-amputee children during walking.

We determined normative ground reaction force data for able-bodied (AB) and below-knee-amputee (BKA) children during walking. Twenty-two BKA and 225 able-bodied children walked over two adjacent force platforms. Average normalized force-time curves were determined for legs of the children for subjective comparisons, and discrete variables were determined for statistical comparisons. No significant differences existed between (a) right and left legs, (b) gender, and (c) age for the AB children. BKA children had an asymmetrical gait pattern with a dominant role of the nonprosthetic limb. This dominant role was related to a greater rate of loading, magnitude of loading, impulse, and time of loading as compared with prosthetic limbs and with the limbs of AB children.

Adolescent↗