One of the worst things for me has been jammed fingers, especially the proximal joint in my left thumb. If you've never suffered this particular affliction, consider yourself fortunate. I have managed to bang my thumb enough so that if I am not careful, I can -- literally -- sprain it while taking my sock off. (The reason for this is that every time you seriously strain or sprain a joint, you create some scar tissue. Scar tissue is less elastic than normal, undamaged stuff, and past a certain point, much less likely to stretch when put under tension -- instead, it tears. Once you have damaged a joint, it never will be 100% thereafter. Sorry, I didn't make the rules, but that's how it is.)
My affliction is known by various terms -- "Gamekeeper's Thumb," or "Skier's Thumb," "Nightstick Thumb," or "Boxer's Thumb ... " you get the idea.
I've had this for thirty years, and since I need my hands for activities other than martial arts, I have tried half a dozen orthopedic devices to stabilize that proximal thumb joint when it is apt to get jammed, including a couple I custom-made using Sculpey.
Most of these work really well when you are sitting in a chair watching TV, but not so well if you are moving. Those that allow thumb-motion generally aren't supportive enough; and those that are supportive enough, don't allow the range-of-motion I want. I need to be able to make a tight fist.
The appliances range from thick Spandex, to heavy-duty leather and Velcro, some with metal inserts, and they can get pretty spendy.
After some trial and error, I came across NexCare's Absolute Waterproof Tape™, a stretchy material that comes in a couple of widths. The one-inch works best for me. I've fooled around with wrapping patterns, and settled on one that seems to work pretty well. It gives my thumb support, but still allows me to open and close my hand.
The tape costs about four and a half bucks a roll, if you buy it in bulk, and I use about half a roll each session -- I do both hands, and most of my fingers' middle joints, so it adds two dollars and little to the cost of my workout. Cheap insurance any way you figure it. The tape is waterproof, doesn't slip off with sweat, and if you use the palm-wrap, stays in place. (I have managed to get sand under the palm-strip when we work out in the sand pit, but even so, it tends to stay on.)
It's not perfect, but it's the best I've been able to devise after a lot of looking. An ounce of prevention and all.
The short movie attached is how I apply the wrapping before each silat class. There is one caveat up front: DO NOT STRETCH THE TAPE AS YOU APPLY IT. Just like an Ace Bandage, you don't want to cut off circulation by stretching it, you want it to be able to give.
If you tension the wrap too much and your thumb rots off, it's your own damn fault, I just told you not to do it.