I have previously mentioned that I am somewhat plagued by osteoarthritis (mostly) in the knees - and the main problem is pain; and the main problem with this pain is that due to side effects (and side effects of the drugs used to combat these side effects) I cannot take any of the effective analgesics (NSAIDs or Aspirin).
The only effective and tolerable analgesic that I have so far discovered is to wear 'tubigrip' - tubular elasticated bandages - around the knee joints...
(and extending down to the ankle, to reduce the risk of deep vein thrombosis if I was to have only knee bandages constricting blood supply above the calf).
These tubigrip bandages offer substantial analgesic benefits (i.e. they significantly reduce pain both at rest and when walking), and do so instantly (as soon as the bandages are applied) - which implies that, to be so rapid, the analgesic effect must be via nerves and not (for example) by reducing-swelling or providing support to the joint.
The likely mechanism by which tubigrip bandages work is by counter-irritation, or the Gate Theory - in other words the tubular bandages stimulate superficial touch receptors in the skin (which have rapid-conducting, myelinated nerve fibres); and these skin sensations then block (or gate) the more slowly-conducting (unmyelinated fibres) pain stimuli from within the knee joint.
The principle is the same as rubbing a limb - quickly and lightly - which you have just bumped and which you know will start to hurt in a couple of seconds time. But if you can start rubbing the skin over the injury immediately, then the touch sensation will travel faster to the central nervous system than the pain sensation (because the myelinated touch fibres beat the unmyelinated pain fibres); and therefore the pain is, to some extent, blocked and reduced.
I have in fact been using tubular bandages on sore joints, including elbows, wrists and ankles, for many years - but used to suppose that they worked by giving support and reducing swelling.
If bandages worked by increasing joint-support and reducing swelling, this would predict that stronger and more compressive bandages would be more effective that lighter and less compressive bandages.
However, I have found the lighter and less-compressive bandages to be more effective (as well as more comfortable). Thus my assumption that the counter-irritation Gate Theory is most likely.
If I am correct about the analgesic mechanism of tubigrip bandages, then the principle could be applied to devise other methods of touch receptor stimulation as an analgesic manoeuvre to treat joint pain; from topical agents (creams) that produce some kind of 'irritation'/ stimulation, perhaps temperature change, perhaps transcutaneous electric stimulation?