This study examined the effects of socket flexion angle in trans-tibial prosthesis on stump/socket interface pressure. Ten trans-tibial amputees voluntarily participated in this study. F-socket system was used to measure static and dynamic pressure in stump/socket interface. The pressure was measured at anterior area (proximal, middle, and distal) and posterior area (proximal, middle, and distal) in different socket flexion angles (5°, 0°, and 10°). Paired t-test was used to compare pressure differences in conventional socket flexion angle of 5° with pressures in socket flexion angles of 0° and 10° (α=.05). Mean pressure during standing in socket flexion angle of 10° decreased significantly in anterior middle area (19.7%), posterior proximal area (10.4%), and posterior distal area (16.3%) compared with socket flexion angle of 5°. Mean pressure during stance phase in socket flexion angle of 0° increased significantly in anterior proximal area (19.3%) and decreased significantly in anterior distal area (19.7%) compared with socket flexion angle of 5°. Mean pressure during stance phase in socket flexion angle of 10° decreased significantly in anterior proximal area (19.6%) and increased significantly in anterior distal area (8.2%) compared with socket flexion angle of 5°. Peak pressure during gait in socket flexion angle of 0° increased significantly in anterior proximal area (23.0%) compared with socket flexion angle of 5° and peak pressure during gait in socket flexion angle of 10° decreased significantly in anterior proximal area (22.7%) compared with socket flexion angle of 5°. Mean pressure over 80% of peak pressure (MP80+) during gait in socket flexion angle of 0° increased significantly in anterior proximal area (23.9%) and decreased significantly in anterior distal area (22.5%) compared with socket flexion angle of 5°. MP80+ during gait in socket flexion angle of 10° decreased significantly in anterior distal area (34.1%) compared with socket flexion angle of 5°. Asymmetrical pressure change patterns in socket flexion angle of 0° and 10° were revealed in anterior proximal and distal region compared with socket flexion angle of 5°. To provide comfortable and safe socket for trans-tibial amputee, socket flexion angle must be considered.

This study examined the effects of the abdominal drawing-in (ADI) maneuver using a pressure biofeedback on muscle recruitment pattern of erector spinae and hip extensors and anterior pelvic tilt during hip extension in the prone position. Fourteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. The muscle onset time of erector spinae, gluteus maximus, and medial hamstring and angle of anterior pelvic tilt during hip extension in prone position were measured in two conditions: ADI maneuver condition and non-ADI maneuver condition. Muscle onset time was measured using a surface electromyography (EMG). Kinematic data for angle of anterior pelvic tilt were measured using a motion analysis system. The muscle onset time and angle of anterior pelvic tilt were compared using a paired t-test. The study showed that in ADI maneuver during hip extension in prone position, the muscle onset time for the erector spinae was delayed significantly by a mean of 43.20 ms (SD 43.12), and the onset time for the gluteus maximus preceded significantly by a mean of -4.83 ms (SD 14.10) compared to non-ADI maneuver condition (p<.05). The angle of anterior pelvic tilt was significantly lower in the ADI maneuver condition by a mean of 7.03 degrees (SD 2.59) compared to non-ADI maneuver condition (15.01 degrees) (p<.05). The findings of this study indicated that prone hip extension with the ADI maneuver was an effective method to recruit the gluteus maximus earlier than erector spinae and to decrease anterior pelvic tilting.

This study examined the ability of human subjects to match a force in their quadriceps muscle during fatigue. Twenty subjects (mean age: 23.4 yrs, mean height: 167.8 cm, mean weight, 62.6 kg) were enrolled in the experiment. In the force-matching task, the quadriceps muscle generated 50% of the MVIC (maximum voluntary isometric contraction) torque under visual control and then without visual feedback. After inducing fatigue in the quadriceps muscle, the subjects were required to match 50% of the MVIC torque without visual feedback. The perceived magnitude of the force and force-matching errors were measured. 50% of the MVIC torque was perceived from 39.96 Nm in the pre-fatigue condition to 44.95 Nm in the post-fatigue condition. 50% of the MVIC torque-matching errors increased significantly from .55% in the pre-fatigue condition to 9.6% in the post-fatigue condition (p<.001). in addition, there were significantly more force-matching errors in women than in men (p<.01). In conclusion muscle fatigue can interfere with a subject's ability to match a force. This suggests that muscle fatigue may contributes to the sensitization of the proprioception.