People with amputations are at increased risk of falling compared with age-matched, able-bodied individuals. This may partly reflect amputation-related changes to minimum toe clearance (MTC) that could increase the incidence of trips and fall risk. A team of researchers from the University of Illinois at Chicago and Scheck & Siress, headquartered in Oakbrook Terrace, Illinois, conducted a study to determine the contribution of an active dorsiflexing prosthesis to MTC. They reported that a prosthetic foot that offers active swing phase dorsiflexion-specifically the Össur Proprio Foot-can significantly increase MTC and reduce the likelihood of a trip in users with transtibial amputations. The study was published in the most recent issue of the Journal of Rehabilitation Research & Development.
For the study, eight people with transtibial amputations walked on a treadmill with their current foot at two grades and three velocities, then repeated the protocol after four weeks of accommodation with the ProprioFoot. A mixed-model, repeated-measures analysis of variance was used to compare MTC. Curves representing the likelihood of tripping were derived from the MTC distributions and a multiple regression was used to determine the relative contributions of hip, knee, and ankle angles to MTC. Regardless of condition, MTC was about 70 percent greater with the ProprioFoot, and the likelihood of tripping was reduced. Regression analysis revealed that MTC with the ProprioFoot was sensitive to all three angles, with sensitivity of hip and ankle being greater. Overall, the ProprioFoot may increase user safety by decreasing the likelihood of tripping and thus the pursuant likelihood of a fall.
The researcher team said that future work should focus on quantifying the extent to which change in MTC can be directly attributed to the active dorsiflexion feature of the foot and measuring trip-related fall risk in people with transtibial amputations. If indeed the increased fall risk of people with transtibial amputations can be partly explained by an increased risk of tripping, then in certain populations (e.g., individuals who trip frequently) the ProprioFoot may help reduce the risk of tripping, the study reports.
