In rely to Vikkiwill:
I have had knee problems occasionally from repetitive stresses (skiing) and individual wrenches (mountain walking). The first bad one was skiing over 30 years ago and I bought a neoprene sleeve with a hole over the kneecap with fairly rigid, hinged, bilateral inserts with two straps. Somewhat unexpectedly it enabled me to continue skiing normally.
I still have the same support and still use it: last time successfully at the end of a skiing holiday last year. It is labelled Snow and Rock and is at least superficially similar to the Bioskin Hinged Kneeskin on their website.
I occasionally carry a couple of cheap, simple, neoprene supports in case of a strain, but they are of comparatively little help.
Presumably the degree of support required varies. More rigid ones are available (I believe the NHS supplies tailor made ones for chronic cases). Lidl had a similar but much more flexible support recently.
Obviously it depends on your problem: I have never had mine diagnosed. These supports are presumably only of use to limit lateral movement.