In reply to mypyrex:
Sigh.
The first hurdle is GP support. If the GP feels it is inappropriate or inadvisable, they will not refer, and there may be many reasons for this - other conditions making surgery inadvisable being very common.
I don't know in Wales, but I expect it's similar to England, in which case hip replacements are what's known as "threshold dependent procedures" - the thresholds being set with recognition of several factors including the fact that it's a major operation with significant impact (and some risk), and with somewhat variable outcomes, as well as the issue of cost. The description of the threshold will be on your local health authority website. If you fall outside this your GP can put in a recommendation to a panel that reviews and decides funding for exceptions.
Once you've got a referral, the orthopedic surgeon may also decide that surgery is not the appropriate intervention, again for a variety of reasons to do with how well they feel the patient will do under surgery and the risks vs potential gains. The problem with hips and knees is that whilst some do very well, about 20% get worse and 40% stay about the same - so it's not a slam dunk win. Also, at 75 issues of a prolonged general anaesthetic may not be trivial, especially if the patient is over or under weight.
Finally, assuming your brother is of sound mind and can make his own decisions, maybe you should let him? The NHS and PALS should take zero notice of your views unless you have health power of attorney (actually they should rightly and properly refuse to discuss his care with you).