Effects of Upper Limb Loss or Absence and Prosthesis Use on Postural Control of Standing Balance.

Abstract

Persons with upper limb loss or absence experience a high prevalence of falls. Although upper limb prostheses help perform upper limb tasks, fall likelihood increases by six times with prosthesis use. The effects of upper limb loss or absence and prosthesis use on postural control are poorly documented. Static posturography characterized postural control of standing balance between persons with unilateral upper limb loss or absence not wearing a prosthesis and wearing either a customary prosthesis or prosthesis that matched the mass, inertia, and length of their sound limb. Able-bodied controls were also compared to persons with unilateral upper limb loss or absence not wearing a prosthesis. Center-of-pressure anterior-posterior range, medial-lateral range, and sway area, as well as weight-bearing symmetry, were measured. Persons with upper limb loss or absence display greater standing postural sway than controls. Although wearing a prosthesis improved weight-bearing symmetry, this condition increased postural sway, which was pronounced in the medial-lateral direction. The presence of upper limb loss or absence increased postural control demands than able-bodied individuals as reflected in greater postural sway, which was further exacerbated with the use of prosthesis. Results suggest that upper limb loss or absence and prosthesis use may affect the internal models that guide motor commands to maintain body center-of-mass position equilibrium. The relatively greater postural control demands might help explain the increase fall prevalence in this patient group.