Energy expenditure of transfemoral amputees walking on a horizontal and tilted treadmill simulating different outdoor walking conditions

Background and aim: Transfemoral amputees often report that walking on tilted pavements or in terrain with the prosthesis on the highest side is quite strenuous. This study investigates the energy expenditure of transfemoral amputees (n=8) walking on altered treadmill positions simulating different outdoor walking conditions. Method: Oxygen uptake at self selected speed of gait was measured during walking at three different treadmill positions: (I) Horizontal treadmill, (II) 3 % tilt in the sagittal plane and (III) 3 % tilt in both the sagittal and frontal plane of the treadmill. Results: The difference in oxygen uptake between position I and II was in median 4,3%, and 16,4% between position II and III (p≤ 0, 05 for all comparisons). The subjects utilized about 50% of their VO_2_max when walking in position I and II while energy expenditure increased to about 60% of the amputees VO_2_max when walking in position III. Conclusion: Transfemoral amputees use significantly more energy when walking on a moderately tilted surface in the frontal plane compared to walking with a tilt in the sagittal plane only. The prosthetic leg becomes functionally too long when the walking surface is tilted sideways, and the transfemoral amputees adopt a more energy consuming gait pattern