Laws of Medicine – Find the ‘Key Sign’

Doctors are men who prescribe medicines of which they know little, to cure diseases of which they know less, in human beings of whom they know nothing.


In orthopedics, I found the most value in finding what a patient knows will cause the pain. Then I make them do it – over and over again. Honestly, my table starts to creak for particularly difficult cases.

I constantly retest the problem after doing a treatment. In a 60 minute session, the patient may do the same activity 30 times. Each time the goal is to find what makes it feel better with treatment. When I find that ‘treatment’ that works, I use it until it stops improving the key sign. I normally search for an 80% improvement.

Key sign

The key sign is a surprisingly simple and useful tool.

After reading, The Laws of Medicine by Siddhartha Mukherjee, I realized that most practitioners practice different laws. These laws develop naturally to improve outcomes. In my experience, the most useful ‘law’ is what hurts and when.

What thing were you able to do yesterday but cannot do today?

Was there a way you used to sit that now hurts? Then I will make you sit to see if the treatment made it better.

Does running now hurt right when you hit the ground? Then I need to make you run and make it not hurt.

Can you no longer stand a full day without debilitating heel pain? Then I need to see you at the end of the day when your heel hurts. If I can make it feel better, then I can help you get better.

Does your knee hurt when you walk? Then lets see if we can make you walk more than you have in the past month without pain.

Too often, we get scared of the key sign instead of excited that there is an easy retest that shows treatment is working. If Voltaire is correct, we can never know enough, but if we make the most bothersome problem better, then maybe we don’t need to.