EFFECT OF TRANSTIBIAL PROSTHESIS MASS ON GAIT ASYMMETRIES

Abstract BACKGROUND: Individuals with transtibial amputation (TTA) typically walk with an asymmetrical gait pattern, which may predispose them to secondary complications and increase risk of fall. Gait asymmetry may be influenced by prosthesis mass. OBJECTIVE: To explore the effects of prosthesis mass on temporal and limb loading asymmetry in people with TTA following seven days of acclimation and community use. METHODS: Eight individuals with transtibial amputation participated. A counterbalanced repeated measures study, involving three sessions (each one week apart) was conducted, during which three load conditions were examined: no load, light load and heavy load. The light load and heavy load conditions were achieved by adding 30% and 50% of the mass difference between legs, at a proximal location on the prosthesis. Kinematic and ground reaction force data was captured while walking one week after the added mass. Symmetry indices between the prosthetic and intact side were computed for temporal (Stance and Swing time) and limb loading measures (vertical ground reaction force Peak and Impulse). FINDINGS: Following seven days of acclimation, no significant differences were observed between the three mass conditions (no load, light load and heavy load) for temporal (Stance time: p=0.61; Swing time: p=0.13) and limb loading asymmetry (vertical ground reaction force Peak: p=0.95; vertical ground reaction force Impulse: p=0.55). CONCLUSION: Prosthesis mass increase at a proximal location did not increase temporal and limb loading asymmetry during walking in individuals with TTA. Hence, mass increase subsequent to replacing proximally located prosthesis components may not increase gait asymmetry, thereby allowing more flexibility to the clinician for component selection. Layman's Abstract People with a below the knee amputation typically have an asymmetrical walking style, i.e., they spend more time and put more body weight on their non-amputated leg. This may result in development of knee or hip osteoarthritis of the non-amputated leg, over time. Further, an asymmetrical walking style may also predispose people to a greater number of falls. It is believed that the weight of a prosthesis may influence the walking asymmetry. It is, however, unclear if changing the weight of a prothesis during routine clinical visits (for example, switching or replacing prosthesis parts) would increase walking asymmetry. To explore this, eight individuals with a below the knee amputation had two different weights added to the top half of their prosthesis. After the addition of the weight, participants went home to use the device in their communities for seven days. Subsequently, they returned to the lab to record their walking. We observed that walking with the heavier prosthesis, using either load, did not increase the amount of time spent and body weight applied by our participants on their non-amputated side. Hence, adding mass to the top half of a prosthesis may not increase walking asymmetry.Corresponding Author: Mayank Seth, PhD Delaware Limb Loss Studies Lab, University of Delaware, Newark, USA. E-mail: mseth@udel.ed