The purpose of this study was to characterise the functional outcome of 12 transfemoral amputees fitted with osseointegrated fixation using temporal gait characteristics. The objectives were (A) to present the cadence, duration of gait cycle, support and swing phases with an emphasis on the stride-to-stride and participant-to-participant variability, and (B) to compare these temporal variables with normative data extracted from the literature focusing on transfemoral amputees fitted with a socket and able-bodied participants. The temporal variables were extracted from the load applied on the residuum during straight level walking, which was collected at 200 Hz by a transducer. A total of 613 strides were assessed. The cadence (46±4 strides/min), the duration of the gait cycle (1.29±0.11 s), support (0.73±0.07 s, 57±3% of CG) and swing (0.56±0.07 s, 43±3% of GC) phases of the participants were 2% quicker, 3%, 6% shorter and 1% longer than transfemoral amputees using a socket as well as 11% slower, 9%, 6% and 13% longer than able-bodied, respectively. All combined, the results indicated that the fitting of an osseointegrated fixation has enabled this group of amputees to restore their locomotion with a highly functional level. Further longitudinal and cross-sectional studies would be required to confirm these outcomes. Nonetheless, the data presented can be used as benchmark for future comparisons. It can also be used as input in generic algorithms using templates of patterns of loading to recognise activities of daily living and to detect falls

This study directly measured the load acting on the abutment of the osseointegrated implant system of transfemoral amputees during level walking, and studied the variability of the load within and among amputees. Twelve active transfemoral amputees (age: 54 +/- 12 years, mass: 84.3 +/- 16.3 kg, height: 17.8 +/- 0.10 m) fitted with an osseointegrated implant for over 1 year participated in the study. The load applied on the abutment was measured during unimpeded, level walking in a straight line using a commercial six-channel transducer mounted between the abutment and the prosthetic knee. The pattern and the magnitude of the three-dimensional forces and moments were revealed. Results showed a low step-to-step variability of each subject, but a high subject-to-subject variability in local extrema of body-weight normalized forces and moments and impulse data. The high subject-to-subject variability suggests that the mechanical design of the implant system should be customized for each individual, or that a fit-all design should take into consideration the highest values of load within a broad range of amputees. It also suggests specific loading regime in rehabilitation training are necessary for a given subject. Thus the loading magnitude and variability demonstrated should be useful in designing an osseointegrated implant system better able to resist mechanical failure and in refining the rehabilitation protocol.

To provide a comprehensive description of the direct measurement of forces and moments applied on the socket of transfemoral amputees during daily living activities. The forces and moments applied on the socket of one female transfemoral amputee were measured with a commercial transducer at a sampling frequency of 200 Hz and recorded at distance using a wireless modem to transmit the data. The subject was asked to walk in a straight line and around a circle as well as to ascend and descend a slope and stairs. The subject was instructed to perform each activity at her natural pace and as she would usually perform it during daily life. The results were based on a high number of gait cycles of the prosthetic leg for each activity. For instance, 62 gait cycles were measured during level walking in a straight line. Ascending a slope produced a larger moment around the mediolateral axis than walking over the entire support phase. In addition, walking around a circle produced a higher moment about the long axis of the socket than walking during the push-off phase of the support. The mean stride frequency while descending a slope was higher than straight level walking. All the other activities presented a slower mean stride frequency than straight level walking. The impulse on the three axes was similar or smaller than walking in a straight line for all of the activities except for walking around a circle on the mediolateral axis, as well as ascending a slope and stairs and walking around a circle on the long axis. An apparatus to directly measure the actual forces and moments applied to the socket of the transfemoral amputees during an unlimited number of steps and a wide range of activities is presented. The apparatus presented here could be used by multidisciplinary teams, including engineers, prosthetists, and physiotherapists, facing the challenge of safely restoring the locomotion of transfemoral amputees fitted with a conventional socket or, in particular, an osseointegrated implant.

Falling represents a health risk for lower limb amputees fitted with an osseointegrated fixation mainly because of the potential damage to the fixation. The pur...