Do you love your thumbs?
I do. My thumbs are amazing. If you pinch something between your thumb and index finger tip, the force which goes through the base of your thumb is amplified by 12 times. So a 1kg pinch (picking up a needle / pen) would put 12kg of force through the base of the thumb. If you grip with any kind of force (such as a hammer or tennis racquet) the force can increase to 120kgs!
This is fairly amazing in itself but then you realise that your thumb balances all this force mainly through ligament support. The shape of the joint is built for movement not stability, so external support is required. There are many ligaments with amazing names, but the main stabilisers are on the front (palm side) and the Dorso-radial (back and towards the thumb side). These are supported by the muscles around the thumb.
We should think about how we support and protect these muscles and ligaments, so the joint can continue to bear the forces we are asking of it, long into the future, without developing arthritic changes. How do we do this? A few simple modifications through our day can help. 1) get some key fobs. The wider the thing you are pinching, the less force is required to pinch it (thus reducing the load at the base). 2) get some pen grips. For the same reason as (1). Or write in pencil. Or any free flow ink pen. Try to avoid biro for long term writing as they are narrow so you grip hard, and you have to press hard to get a mark on the paper. 3) try not to text with one thumb, on the same hand you are using to hold your phone. I know it makes you look daft but typing with both sides equals the balance a bit, 4) use aids to increase the surface area you grip: tape around your racquet handle, a glove to grip the golf club / handlebars / weights. 5) make sure your equipment is the correct size for you, not too heavy or light and you are balancing it correctly (such as when shooting) to avoid unnecessary force production 6) use aids like easy open scissors, electric tin openers, and ensure your tools are sharp – easier to use and therefore less force is required.
Love your thumbs. I do. – Anne Alexander, Specialist Hand Therapist