In one study, the center of pressure (CoP) remained proximal to the end of the residuum in persons with transmetatarsal (TMT) and Lisfranc amputation using toe fillers, insoles, and slipper sockets [9-10].
Results from this investigation suggest that if below-ankle devices are being used in persons with TMT or Lisfranc amputation, the forefoot stiffness of these devices need not be a design consideration.
To ensure these insights are not taken out of context, we wish to make explicit that the following discussion applies only to the gait of persons with TMT and Lisfranc amputations.
Results from this investigation make clear that the device must be designed to control the external moments caused by loading the prosthetic forefoot because in persons with TMT and Lisfranc amputations, the calf musculature is not providing this control because of weakness (Table 2), disuse, or discomfort on the distal plantar aspect caused by concentric contraction.
This investigation provides insights into the effect of device design on the gait of persons with TMT and Lisfranc amputations.
an anterior tibial shell) if they wish to restore the effective foot length in persons with TMT and Lisfranc amputations.
During terminal stance, consistent reductions in the magnitude of the horizontal GRF were observed, along with premature timing of the peak, in the subjects with TMT and Lisfranc amputation (Figure 1(b)).
The vertical GRF patterns observed on the sound limbs were quite variable during loading (Figure 2(a)), with the magnitude of the vertical GRF increased in the subjects with Lisfranc amputation beyond the 95% CI of the control cohort.
In the subjects with TMT and Lisfranc amputation, the GRF remained at a relatively fixed position (40%-50% of shoe length) until about contralateral heel contact, which occurred at 50 percent GC (Figure 3(b)).
Peak ankle dorsiflexion was delayed and exaggerated compared with the control group on the affected limbs of the subjects with TMT and Lisfranc amputation, and peak plantar flexion was reduced compared with the control group as well (Figure 6(b)).
On the affected limbs of the subjects with TMT and Lisfranc amputation, a normal knee moment pattern was observed until just after foot flat (Figure 8(b)), after which an extension moment was maintained until about 40 percent GC, when the magnitude of the moment was close to zero.
The subjects with TMT and Lisfranc amputation exhibited a peak plantar flexion moment of between one-third and two-thirds that of the control group (Figure 9(b)).