Have you ever worked with a patient who suffered from thumb pain? Or have you as an occupational therapist suffered from thumb pain?
The thumb does 50% of the work of your hands. So if you don’t believe me, try to do ANYTHING without your thumbs.
Why do you think when someone cuts off their thumb, it’s replaced with a toe?
YES! Thumbs are so important. They are important for your patients, and they are important for you as the hand therapist.
Anatomy of the thumb and why you should know it.
Think about the shape of the thumb joint. It’s complex concave and convex shaping allows it great mobility.
Think about how the ligaments of the thumb give the thumb stability. It has to be lax enough to allow mobility, and strong enough for stability. When we think about ligaments, we think about what ligaments are, then we think about capsules.
So what are ligaments? Ligaments are just connective tissue that’s made out of collagen fibers. Sometimes people are a little bit more loosey-goosey, which means they have a lot of play in their ligaments. The purpose of a ligament is to connect the two bones and give stability. It holds the joint in place, and then the capsule gives it extra stability. The capsule is created by many things like collagen fibers, connective tissue, and a lot of ligaments.
When it comes to the thumb, there’s a couple of important ligaments. The anterior oblique ligament, your ulnar collateral ligament, your posterior oblique, your intermetacarpal ligament, and then your dorsal radial. Now, a lot of these ligaments, oblique means at an angle, collateral means to the side, and the posterior is to the back.
Now, your thumb’s CMC ligaments, the ulnar collateral ligament is if you injure it, it’s a gamekeeper’s thumb, but not at the CMC. So this is the same ligament because at the MP is the gamekeeper’s thumb also.
They have the same name, but they do different things, so injuries are different. Pay attention when you’re dealing with these types of injuries. The anterior oblique ligament is very important because it is the major stabilizer, and it’s tight when the thumb is in abduction, extension, and opposition, right, at the CMC level. It is tight in abduction, extension, and opposition.
The other two that are as important as this one are the posterior oblique and the dorsal radial. These two ligaments stop against subluxation during power and stop against dorsal subluxation during power, grip, and pinch. So the thumb’s ligaments at the CMC hold that base of the thumb, giving it stability and mobility. The joint capsule around there is complete, but it’s loose to allow mobility.
Anytime you think, “Oh, what’s going on with the CMC ligaments?” they’re supposed to be loose to give you a certain amount of motion. But what happens when it’s too loose?
Here’s what you’re going to have to think about as it pertains to rheumatoid arthritis.
Why are the ligaments important for people with rheumatoid arthritis and those with different types of thumb CMC problems? Because these ligaments give them stability, and their thumb moves places or falls into their palm if they don’t have it. This is why the different types of arthritis are going to challenge your knowledge of the thumb CMC.
Now, when it comes to the metacarpal joints, the carpal, metacarpal joints. Right, two and three don’t have any motion because three gives us weight-bearing potential, and two is the largest and doesn’t move. And you could feel it in your hand, I encourage that because when you feel it, you’re going to feel between four and five, there is some give, there’s a small amount of motion.
If you take a look at your metacarpal all at the base, there’s a little bit of motion that you have. That mobility that you have here on the ulnar side of your hand is what allows you to move. It will enable fine motor and cupping of your hand like when you cup up some water.
It also allows you to have a grip because when you grip, these two are your power grip, and it’s because you’re CMC at three and four have more motion. So with those, you don’t have to really dive into all the ligaments of that because, again, these are your stability ones between the carpal bones and the metacarpal bones at the base.
Now, we’re going to move the metacarpal’s head to P1, to the proximal phalanx, and that’s your MPs. So here comes, really, a lot of where the confusions are. Yeah, so the CMC at four and five, at four and five.
Understanding the anatomy of the thumb CMC joint is the key to applying how you look for where the problems are for your patients and is the guide to helping to apply what you know for treatment.
Once you know the structures, you have a great chance of knowing what to look for in an evaluation and how to treat the injury for the best possible results.
This is not only important for your patients. It’s important for you. I often hear of therapists who go into hand therapy thinking that it will be easier.
Yes, it may be easier on your back, but certainly not on your hands.
Take care of your thumbs because when you have pain that you can’t get rid of, it’s too easy for you to think that your patients can’t get rid of theirs either.Want to become a Certified Hand Therapist? Grab the details of our Hand Exam Prep program to help you become the critical thinker, problem solver, and decision maker – and pass the exam!