RehabMove 2018: Biomechanical effects of a carbon fibre foot with a pronounced range of motion on ramps

Walking on inclines is a challenging task for amputees. 3D gait analyses were conducted in 23 unimpaired persons (REF) and 11 patients with transtibial amputation (PTTA) investigating the biomechanical effects of a novel foot with a mechanical pivot unit (ProFlex, Össur, IS) compared to a VariFlex (VA/, Össur, IS) while walking on an instrumented 10° ramp. Additionally the “Soleangle” (angle between foot and ramp) was calculated. Ankle range of motion was in PF significantly greater than in VA. Angular velocity of “Soleangle” was significantly greater in VA compared to PF ramp up and down. In VA condition PTTA showed two different strategies, one with a pronounced knee flexion in stance close to REF (VA1) and one with a significant hyperextension of the knee joint (VA2). PF showed only one pattern, which was close to REF but with a more extended knee joint than VA1 and REF. PEQ ambulation scale for uphill and downhill walking showed significant improvements by 20% using PF.
Results indicated that a rigid lever arm of VA compared to PF might not always be beneficial. However flexibility of the PF did not lead overall to reduced knee moments on the ramp, but the early foot flat and resulting adequate adaptation to the incline indicated a sufficient support during ramp walking. The findings were supported by PEQ results.