Re: Which bone is most frequently broken ?

Dear Matt and Vince,

The bone most often broken in the human body is the clavicle. This s- shaped bone (also called the collar bone) connects the scapula ("shoulder bone") to the sternum ("breast plate"). See an x-ray here.

Why is this bone broken more often than any other? There is a pretty interesting answer. When people fall, they instinctually try to hold out their arms to brace themselves with their hands. This is important, because if the fall wasn't broken with outstretched hands, the body would smash against the ground, and possibly damage vital internal organs.

So when a person falls, they often jam their hands hard into the ground. There is quite a bit of force transferred from the hands up the person's arms. If the fall was hard enough, the large force will be passed through the shoulder joint to the clavicle. If there's still enough force, the clavicle will break at it's first curve, approximately 1/3 of the way along the bone.

Some people break their collar bones more often than others. The biggest factor is the strength of the bone. Bone strength is dramatically reduced in people with osteoporosis. There is a lot of good information about osteoporosis from the National Osteoporosis Foundation.

Professional athletes take hard falls all the time. But they don't break their collar bones as often as we'd predict. This is because they've been trained on how to fall in special ways to pass force to the outside of their bodies, instead of to the inside, where the clavicle lies.

Some martial artists are extemely good at this. See a picture of an Aikido roll. For a diagram of how such rolls are performed, see thi s diagram from the Aikido FAQ. Many video clips of different falls are available at the same site.


Thank you for your question,

John Carlson, MAD Scientist