In-vivo Kinetic System to sustain residuum health of service members with lower limb loss: From proof-of-concept to digital twin

The ability of military Service members, Veterans and beneficiaries with lower limb loss to walk with a prosthesis is paramount to their quality of life and essential for a return to active duty. Consequently, prosthetic care providers make bespoke clinical decisions intending to sustain the capacity of residuum to sustain fitting of the prosthesis. The term ‘Residuum Health’ describes the physical well-being of the neuro-musculo-skeletal system, encapsulating resected skin, nerves, muscles and bone that may be compromised by acute and chronic skin issues, oedema, neuroma, muscle contractures, stress fractures, osteopenia and heterotopic bone growth. Choice and alignment of components for socket-suspended prostheses are critical to generate acceptable loading profiles and subsequent intra-socket pressures. For example, enabling individuals to apply half and full bodyweight loading is essential whilst standing and ambulating safely, respectively. This could also minimize risks of skin damage, often responsible for prosthesis abandonment. The ‘Goldilocks’ loading regimen applied by bone-anchored prostheses is also critical for safe and efficient osseointegration around the implant during rehabilitation and beyond. Under-loading might lead to loosening and infection while over-loading might compromise the bone–implant interface. To date, the effects of components and their fitting on loading regimen during daily activity could only be assessed using portable kinetic systems, relying on transducers embedded in a prosthesis. However, these device provide only minimal means to explore the relationships between loading and residuum health (e.g., skin damage risks). Since 2016, we have been developing a portable and non-invasive In-vivo Kinetic System that integrates prosthetic loading applied to the residuum (e.g., forces and moments) and novel Dynamic Anatomical Ultrasonography (DAU), that simultaneously captures residuum tissue displacements (e.g., residual bone) during dynamic conditions (e.g., daily activities). The objectives of this presentation are to provide the outcomes of proof-of-concept, and preliminary clinical utility studies.