Adaptations from the prosthetic and intact limb during standing on a sway-referenced support surface for transtibial prosthesis users

Abstract

Purpose: To investigate the bilateral postural adaptations as a result of standing on an increasingly unstable sway-referenced support surface with both the intact and prosthetic limb for transtibial prosthesis users (TPUs).Method: TPUs (n = 14) and matched controls (n = 14) stood quietly in multiple foot placement conditions (intact foot, prosthetic foot and both feet) on a sway-referenced support surface which matched surface rotation to the movement of the centre of pressure (CoP). Force and motion data were collected and used to analyse CoP mean position, displacement integral and force components under intact and prosthetic limbs.Results: Significant differences were found between prosthesis users and controls in CoP mean position in anteroposterior (1.5 (95% CI, 1.2–1.8) cm) and mediolateral directions (3.1 (95% CI, 0.5–5.7) cm. CoP displacement integrals were significantly different greater for prosthesis user group in the anteroposterior direction. Force components differences were found in all planes (anteroposterior: 0.6 (95% CI, 0.4–0.8 N); mediolateral: 0.1 (95% CI, 0.0–0.2 N & 0.3 (95% CI, 0.2–0.4) N, inferosuperior: 2.2 (95% CI, 1.4–3.0) N).Conclusions: TPUs have bilateral static and dynamic postural adaptations when standing on a sway-referenced support surface that is different to controls, and between prosthetic and intact sides. Results further support evidence highlighting importance of the intact limb in maintenance of postural control in prosthesis users. Differences indicate clinical treatment should be directed towards improving outcomes on the intact side.Implications for rehabilitationProsthesis users have bilateral adaptations when standing on a sway referenced support surfaceThese adaptations are different to controls, and between prosthetic and intact sides.The intact limb is the major contributor to maintenance of postural control in prosthesis users.Clinical treatment should account for this when interventions are designed.