Robot-mediated overground gait training for transfemoral amputees with a powered bilateral hip orthosis: a pilot study.
Clara Beatriz Sanz-Morère, Elena Martini, Barbara Meoni and 12 others
PMID 34217307WHAT IT FOUND
Seven transfemoral amputees completed a four-week overground training program with a powered hip exoskeleton.
Walking speed and symmetry improved after training, but wearing the device during assessment slowed walking and increased metabolic cost compared to walking without it.
Key findings
01After training, participants walked further and faster without the exoskeleton, with median speed increases of 13.7% in the symmetry-focused group and 17.9% in the speed-focused group.
02Wearing the exoskeleton during assessment reduced walking speed by a median of 5.4% (symmetry group) and 4.7% (speed group), and increased metabolic cost in nearly all participants.
03Gait symmetry improved post-training, with the symmetry group showing a 3.6% improvement in temporal symmetry index, while the speed group showed minimal change.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
No control group: It is impossible to determine if the improvements were due to the exoskeleton or simply from increased exercise volume and conventional gait training. Small sample size: Only seven participants, with two completing only partial training, limits generalizability and statistical power. Heterogeneous population: Participants varied widely in amputation level, prosthesis type, and baseline mobility, making it difficult to isolate the device's effect. Assessment order: The 'with exoskeleton' condition was always performed after the 'without' condition, which may have introduced fatigue or learning biases. Metabolic cost findings: The increased metabolic cost while wearing the device contradicts some prior literature and may be related to the specific device design or tuning strategy used.
Declared interests
The study was supported by non-U.S. government funding. The authors are affiliated with research institutions developing the Active Pelvis Orthosis, which may introduce a conflict of interest regarding the device's evaluation.
The easy way to misread this
Do not conclude that the exoskeleton improves walking while it is being worn. The study found that wearing the device slowed walking and increased metabolic cost. The improvements in speed and symmetry were observed only after training, when participants walked without the exoskeleton, and without a control group, it is unclear if these gains were due to the robot or the additional exercise.