Considering passive mechanical properties and patient user motor performance in lower limb prosthesis design optimization to enhance rehabilitation outcomes

Abstract

Background Selection of prosthesis mechanical characteristics to restore function of persons with lower-limb loss can be framed as an optimization problem to satisfy a given performance objective. However, the choice of a particular objective is critical, and considering only device and generalizable outcomes across users without accounting for inherent motor performance likely restricts a given patient from fully realizing the benefits of a prosthetic intervention. Objectives This review presents methods for optimizing passive below-knee prosthesis designs to maximize rehabilitation outcomes and how considerations on patient motor performance may enhance these outcomes. Major Findings Available literature supports that considering patient-specific variables pertaining to motor performance permits a multidimensional landscape relating device characteristics and user function, which may yield more accurate predictions of rehabilitation outcomes for individual patients. Moreover, the addition of targeted physical therapeutic interventions that encourage user self-organization may further improve these outcomes. We note the potential of existing paradigms to address these additional dimensions, and we encourage investigators to consider the many different performance objectives available for prosthesis optimization. Conclusions By considering user motor performance in combination with prosthesis mechanical characteristics, a staged optimization approach can be formulated which acknowledges that device modifications may only improve outcomes to a certain extent and user self-organization is a critical component to complete rehabilitation. An iterative process that can be integrated within existing rehabilitative practices accounts for changes in patient status through combined targeted prosthetic solutions and physical therapeutic techniques, and embodies the concept of personalized intervention for patients with lower limb-loss.

Perturbation recovery during walking is impacted by knowledge of perturbation timing in below-knee prosthesis users and non-impaired participants

“…Given this relationship, it is possible that when the timing of perturbation was known, individuals may have employed a multi-step preparatory strategy so that the point in the gait cycle when the perturbation occurred aligned with instances when the CoM medial-lateral velocity was small or directed in the opposite direction of the perturbation. This association supports the theoretical relationship between CoM velocity (and hence body momentum) and frontal-plane balance control [ 36 , 42 ], and also highlights regions of the gait cycle to target when the desire is to implement challenging disturbances for stability training interventions [ 43 ].…”

Amputee perception of prosthetic ankle stiffness during locomotion

“…Whether or not a patient’s preferred stiffness is close to the ‘ideal’ stiffness is unknown. There are a multitude of quantitative and qualitative factors that are likely to be optimized in combination by either the prosthetist or patient, such as step length symmetry, limb loading, roll-over, or socket comfort [ 7 ]. Moreover, what a patient prefers in a clinical setting may not be the most comfortable, stable, or energetically optimal outside the clinic or long-term; adaptation of gait can continue for weeks past prescription [ 22 ].…”

“…The process of matching patients with appropriate prosthetic componentry is traditionally based on experiential decisions of clinicians. Consequently, selection of a specific component might be generally acceptable to a prosthesis user, but limit achievement of their full rehabilitation potential [ 7 ].…”

Fall Prevalence and Contributors to the Likelihood of Falling in Persons With Upper Limb Loss

“…Such a response may be risky for commonly-prescribed devices not intended for this purpose and hence result in a failed recovery or additional injury. Overall, the body system must account for presence of the prosthesis to optimize motor responses to a postural disturbance, and this could be encouraged through the balance-targeted physical therapies such as those recommended for lower limb prosthesis users 84 . Further research is warranted to better understand the factors that underlie the relationship between upper limb prosthesis use and the likelihood of falling to direct interventions for maximizing stability.…”