Mauricio Riveras; Emiliano Ravera; David Ewins; Aliah F. Shaheen; Paola Catalfamo Formento
Gait and Posture
Abstract
Background: Minimum Toe Clearance (MTC) is defined as the minimum vertical distance between the lowest
point under the front part of the foot and the ground, during mid-swing. Low values of MTC and walking on
inclines are both related to higher probability of tripping and falling in lower limb amputees. New prosthetic
designs aim at improving MTC, especially on ramps, however the real effect on MTC still needs investigation.
The objective of this study was then to evaluate the effect of different prosthetic designs on MTC in inclined
walking.
Methods: Thirteen transtibial amputees walked on a ramp using three different prostheses: non articulating ankle
(NAA), articulating hydraulic ankle (AHA), and articulating hydraulic ankle with microprocessor (AHA-MP).
Median MTC, coefficient of variation (CV), and tripping probability (TP) for obstacles of 10 and 15 mm were
compared across ankle type in ascent and descent.
Findings: When using AHA-MP, larger MTC median values for ascending (P ≤ 0.001, W = 0.58) and descending
the ramp (P = 0.003, W = 0.47) were found in the prosthetic limb. Also significantly lower CV was found on the
prosthetic limb for both types of AHA feet when compared to NAA for descending the ramp (P = 0.014, W =
0.45). AHA-MP showed the lowest TP for the prosthetic leg in three conditions evaluated. On the sound limb
results showed the median MTC was significantly larger (P = 0.009, W = 0.43) and CV significantly lower (P =
0.005, W = 0.41) when using an AHA in ascent.
Interpretation: Both AHA prosthetic designs help reduce the risk of tripping of the prosthetic limb by increasing
the median MTC, lowering its variability and reducing TP for both legs when ascending and descending the
ramp. For most of the conditions, AHA-MP showed the lowest TP values. Findings suggest that AHA prostheses,
especially AHA-MP could reduce the risk of tripping on ramps in amputees.
Fig. 1.c) Estimation of the walking surface and MTC. MTC*: MTC according to definition, MTC: the value of MTC calculated in this study, MAXl: local maximum and minl: local minimum.
Keywords:
- Gait analysis
- Hydraulic prosthetic foot with microprocessor control
- Energy storage and return prosthetic foot
- Prosthetic safety
- Amputee gait