Safety assessment of running with a bone-anchored prosthesis in a person with a transtibial amputation : a pilot study

Bone anchored prosthesis (BAP) is a promising approach for transtibial amputees to enable a direct load transfer and prevent socket-related problems. However, it is unknown if high load/ dynamic activities, such as running, is safe. Mechanical failure of the implant or bone could lead to fractures resulting in dangerous situations for the amputee following trauma surgery interventions and explantation of the device. In the recent years, osseointegrated implants for BAPs performed well in walking, but limits of mechanical loads are unknown. The aim of this study was to determine the loads acting on the implant during running versus walking, the effect of a running specific prosthesis (RSP) versus a Daily use prosthesis (DUP), and the speed of running. Experimental gait data was obtained for a unilateral transtibial amputee with a bone anchored prosthesis. Experiments were performed for walking and running on a DUP and a RSP. Two multi body models of the participant with either prosthesis were constructed to express the local forces and moments acting on the implant and dual cone adapter in a local reference frame. It was found that local forces in the transverse plane and bending moments about AP and ML axes were smaller during running compared to walking, but axial compression forces were higher for running. Temporal load distribution was different between DUP and RSP, but magnitudes were similar. The effect of increasing running speed did not increase localised implant loads significantly, it resulted in an increased ground reaction force for the intact limb, but effect on the prosthesis side was minimal.