Use of posturography in patients with ankylosing spondylitis: A systematic review.

Only five studies were included, they were all cross-sectional snapshots, and most were small. Only one study explained how it decided on its sample size, so several were probably too small to give a reliable answer. Each study measured a different set of centre-of-pressure values and used a different test protocol, so the results could not be pooled and the studies disagreed about which direction of sway is most affected. A cross-sectional study takes one measurement in time. It can show that people with AS sway more than healthy people, but it cannot say whether the balance problem comes before the disease, tracks with its severity, or responds to treatment. The review covered only quiet standing on a force platform and left out dynamic balance testing, so it says nothing about balance during walking, turning or reaching. One included study had only four patients with AS and another included people over 70 while the others did not, so the patients described across the studies are not a uniform group.

The only declaration in the paper is about funding: the authors state the review received no specific grant from any public, commercial or not-for-profit funding source. No other conflict of interest statement is given.

Do not read this as evidence that balance training works in ankylosing spondylitis. The review only compared how people with AS stand on a force platform against healthy controls; no treatment was given to anyone. The suggestion that balance and postural control exercises should be considered in practice is the authors' recommendation, not a result from this study.