Regarding topical analgesics, in general it's true that they don't penetrate enough to relieve joint pain. There may be a few exceptions when the joint is immediately below the skin without a thick layer of fat or muscle. However over the past few weeks I've tried everything on my aching shoulder (injured when I was hit by a car last month): muscle rubs containing menthol, eucalyptus, salicylates, camphor, capsaicin, you name it, I've tried it. None of it worked.
What probably does help some folks is the rubbing and massaging action that goes along with applying those topical concoctions. It gets the blood flowing, applies pressure that can feel good, etc.
But I got more benefit from a friend's massaging chair with those kneading finger doodads on my neck and shoulders -- no ointments needed. Ditto, cold and hot packs, and soaking in a hot bath.
Unfortunately over the weeks since my right shoulder was injured, I've also injured my left shoulder by using it too heavily for house work, vacuuming and trying to reach across my chest and behind my back to massage my right shoulder. I accidentally dislocating my own left shoulder and now it aches, pops and crunches almost as badly as the impact-damaged right shoulder.
I've tried a CBD topical -- no effect. I suspect CBD and any material claimed to offer analgesic properties through the skin would need to be used with DMSO as a carrier to be effective.
However CBD ingested -- in capsule form, as a tea, powder or oil -- seems to be effective. But I described that in more detail a couple of days ago, above.
A more recent topical analgesic -- Voltaren or diclofenac -- is claimed to penetrate the skin effectively enough to deliver NSAIDs to joints. I don't know whether the diclofenac itself penetrates the skin or the topical version is in a carrier that penetrates the skin. It was prescribed for me but after waiting two weeks and another two hours in the hospital pharmacy waiting room I gave up and tried something else. The literature says it's proven useful only for osteoarthritis, which I don't have. I'm recovering from a shoulder injury and inflammation and pain related to trauma. So I suspect the prescription was a distraction by health care professionals who are under pressure -- at threat of disciplinary action -- to stop prescribing opiates.
I'm pretty sure these doctors and nurse practitioners know that most patients don't abuse prescription pain relievers, and that there are no equally effective commercially available substitutes. Opiates have been used for millennia because they work to reduce severe pain, far more effectively than anything else. And it's pretty obvious when the same doctors and NPs who told us five years ago not to take so much ibuprofen, but are now advising us to take 800mg four times a day, realize how ridiculous it sounds to well informed patients. But their hands are tied, under threat, and apparently they aren't even permitted to discuss it with patients.
And, as I mentioned earlier in this thread, our health network pain management clinic -- the only place authorized to prescribe opiates or controlled pain relievers beyond 10 days -- has a three month waiting period. Clearly they're overwhelmed and not serious about actually providing pain relief for patients. Right now the entire health system is in a cover-their-own-butts phase.
So those of us suffering chronic pain, or new pain due to trauma, are pretty much on our own. Fortunately there are some effective alternative remedies and it's possible more of the cannabis and/or hemp based products will become more mainstream. The main obstacle right now is the FDA, which hasn't officially agreed with court decisions. For those of us who suffer from occasional severe headaches due to migraine, cluster headaches or trigeminal neuralgia, I'm hoping they'll approve some THC based products that have been proven effective at relieving those types of severe headaches. I've tried various prescription meds and all carry significant health risks, particularly cardiovascular complications with risk of heart attack and stroke.