People with upper-limb loss or absence experience a high prevalence of falls, and prosthesis use increases fall likelihood by six times, according to a study conducted to further document the effects of upper-limb absence and prosthesis use on postural control. The study concluded that upper-limb loss or absence increased postural control demands as reflected in greater postural sway than able-bodied individuals, and was further exacerbated with the use of a prosthesis. While wearing a prosthesis improved weight bearing symmetry, this condition increased postural sway, which was pronounced in the medial-lateral direction.
The 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, according to the study’s authors. The relatively greater postural control demands might help explain the increase fall prevalence in this patient group.
The researchers used static posturography to characterize 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. Center-of-pressure anterior-posterior range, medial-lateral range, and sway area was measured, as well as weight bearing symmetry.
The study, conducted by researchers from Northwestern University Prosthetics-Orthotics Center and the Jesse Brown VA Medical Center, was published in Physical Medicine & Rehabilitation.