Is biomechanical loading reduced in individuals with unilateral transtibial amputation during fast-paced walking when using different ankle/foot prostheses? A pragmatic randomized controlled trial.

Everyone had a well-fitting socket and came from private health care, and all of them normally used an energy-storing foot. Nobody had recent experience with the SACH foot, which the authors say may have made the SACH foot look worse than it is. People used each foot for only two weeks before testing, so they may not have fully adjusted to it, and the authors admit the acclimatisation period was short. Twenty people were tested at a single centre, 17 of them men, and all were relatively high-functioning walkers (K classification 3 or 4). Anyone with a less good socket fit, less walking ability, or amputated more recently is not represented. The study measured estimated joint loading, not osteoarthritis. It cannot say whether any of these feet change the risk of developing knee arthritis. The research team told people to slow down or speed up during testing to stop them running. The authors state this may be why the differences in walking pattern between the three feet were so small. The comparison with normal-paced walking draws on previously published data from the same participants, and the full percentage figures sit in supplementary tables that are not part of the article text.

The authors declared no competing interests. The research was paid for out of the supervisors' own research funds. Össur hf, the company that makes two of the three feet tested (the Vari-Flex and the Pro-Flex), pays for the open-access publication of this article.

Do not read this as proof that the Pro-Flex foot protects the knee joint. It lowered the peak sideways moment and peak force on the intact side, but the force arrived faster with that foot, the knee flexion moment on the intact side was unchanged, and the study measured estimated joint loads rather than arthritis in 20 people over short testing sessions.