Knee rotationplasty: motion of the body centre of mass during walking.
Viviana Rota, Maria Grazia Benedetti, Yusuke Okita and 2 others
PMID 27685013WHAT IT FOUND
In three patients with knee rotationplasty, muscle work during walking was in line with normal values for speed, but push-off power was asymmetric.
The unaffected limb supplied most power, while the rotated limb supplied much less.
Key findings
01For the KRP patients, muscle work per distance and pendulum recovery were in line with normal values for the corresponding walking velocity.
02There was a trend toward higher pendulum recovery and lower work per distance in the KRP patients than in amputees and healthy controls.
03In KRP patients, most positive power at push-off came from the unaffected lower limb, and much less power was provided when the affected lower limb was in rear position.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only three KRP patients were studied, and they were all athletes, so this does not show what happens in a broader KRP population. The comparison groups were not measured alongside the KRP patients; healthy control and amputee data came from earlier studies. Walking speed and measurement method differed between groups: controls and above-knee patients walked at 0.75 m/s, while below-knee and KRP patients walked at about 1 m/s. Only six strides were analysed, although previous work found no significant reduction in variance between series of five or 10 walks. KRP is rare; the authors report 42 survivors in Italy, all operated at the same hospital. The study reports walking mechanics, not a treatment effect, so it cannot show that any intervention improves function.
The easy way to misread this
Do not read the trend toward higher efficiency as proof that knee rotationplasty walking is better than amputation. The study had only three professional athletes, compared them with earlier control and amputee data, and used different walking speeds and methods.