Do predictive relationships exist between postural control and falls efficacy in unilateral transtibial prosthesis users?

Objective: To assess whether variables from a postural control test relate to and predict falls efficacy in prosthesis users. Design: Twelve-month within and between subjects repeated measures design. Participants performed the Limits of Stability (LOS) test protocol at study baseline and at 6-month follow-up. Participants also completed the Falls Efficacy Scale-International (FES-I) questionnaire, reflecting the fear of falling, and reported the number of falls monthly between study baseline and 6-month follow-up, and additionally at 9- and 12-month follow-ups. Setting: University biomechanics laboratories. Participants: A group of active unilateral transtibial prosthesis users of primarily traumatic etiology (PROS) (n=12) with at least one year of prosthetic experience and age and gender matched control participants (CON) (n=12). Interventions: Not applicable. Main Outcome Measure(s): Postural control variables derived from centre of pressure data obtained during the LOS test, which was performed on and reported by the Neurocom Pro Balance Master, namely; reaction time (RT), movement velocity (MVL), endpoint (EPE) and maximum (MXE) excursion and directional control (DCL). Number of falls and total FES-I scores. Results: During the study period, the PROS group had higher FES-I scores (U = 33.5, p =0.02), but experienced a similar number of falls, compared to the CON group. Increased FES-I score were associated with decreased EPE (R=-0.73, p=0.02), MXE (R=-0.83, p<0.01) and MVL (R=-0.7, p=0.03) in the PROS group, and DCL (R=-0.82, p<0.01) in the CON group, all in the backwards direction. Conclusions: Study baseline measures of postural control, in the backwards direction only, are related to and potentially predictive of subsequent 6-month FES-I scores in relatively mobile and experienced prosthesis users

Development of a theoretical model for upright postural control in lower limb prosthesis users

Methods used to assess quiet standing in unilateral prosthesis users often assume validity of an inverted pendulum model despite this being shown as invalid in some instances. The aim of the current study was to evaluate the validity of a proposed unilaterally-constrained pin-controller model in explaining postural control in unilateral prosthesis users. Prosthesis users were contrasted against the theoretical model as were able-bodied controls that stood on a platform which unilaterally constrained movement of the CoP. All participants completed bouts of quiet standing with eyes open, eyes closed and with feedback on inter-limb weight bearing asymmetry. Correlation coefficients were used to infer inverted pendulum behavior in both the anteroposterior and mediolateral directions and were derived from both kinematic (body attached markers) and kinetic (centre of pressure) experimental data. Larger, negative correlation coefficients reflected better model adherence, whilst low or no correlation reflected poorer model adherence. Inverted pendulum behavior derived from kinematic data, indicated coefficients of high magnitude in both mediolateral (all cases range 0.71–0.78) and anteroposterior (0.88–0.91) directions, irrespective of groups. Inverted pendulum behavior derived from kinetic data in the anteroposterior direction indicated validity of the model with large negative coefficients associated with the unconstrained/intact limbs (prosthesis users: − 0.45 to − 0.65, control group: − 0.43 to − 0.72), small coefficients in constrained/prosthetic limbs (prosthesis users: − 0.02 to 0.07, control group: 0.13–0.26) and large negative coefficients in combined conditions (prosthesis users: − 0.36 to − 0.56, control group: − 0.71 to − 0.82). For the mediolateral direction, coefficients were negligible for individual limbs (0.03–0.17) and moderate to large negative correlations, irrespective of group (− 0.31 to − 0.73). Data suggested both prosthesis users’ and able-bodied individuals’ postural control conforms well to that predicted by a unilaterally-constrained pin-controller model, which has implications for the fundamental control of posture in transtibial prosthesis users

Exploring the perspectives of prosthetic and orthotic users: past and present experiences and insights for the future

Purpose: The aim of this work was to qualitatively explore the personal perspectives of prosthetic and orthotic users, in the context of their past and present experiences and understand their insights for the future. Materials and methods: A narrative exploration study design, employing a phenomenological approach was used. Semi-structured interviews were conducted with three female and two male prosthetic and orthotic users from Australia and the United Kingdom. Interviews were analysed, coded and key themes and sub-themes identified. Results: Three themes were identified. The Maximising Opportunity theme linked sub-themes of recreation and pushing boundaries. The Health Care Network theme included sub-themes of communication, peer support and building a team. The final theme, Changes over time, included sub-themes of disability perception, advice and advancements over time. Conclusion: Prosthetic and orthotic users identified that there had been vast changes in disability perception, disability rights, and their role in the health care system, along with the variety of technology and materials available. Key findings were that prosthetic and orthotic users want to be listened to, considered central to the health care team, and had a deep understanding of their own health care needs