Lets start with the sternum. This dagger shaped breast bone is the most commonly fractured bone in the body - because of heart surgery. We as cardiac surgeons break and fix more bone than most other bone handling surgeons including orthopods.
The sternum is a cancellous bone which means it is thin and has a hollow interior with marrow in it. It is also spongy or trabecular bone. It is very porous and contains red bone marrow, where blood cells are made. It is weaker and easier to fracture than cortical bone, which makes up the shafts of long bones. Little wonder that this bone that we typically break in a controlled fashion as we enter the chest and then bring together at the end of the heart operation - is prone to complications in terms of healing, pain, infection, etc.
Historically, this has been closed with wire cerclage - getting the 2 halves of the sternum together and lashing them together with stainless steel wire. However, this may be not sound bio-mechanically because the chest is constantly moving and complete immobilization of the bony components is not possible. Rigid fixation of the bone without movement of the bony fragments is vital for bone healing.
We have over the past 18 years been witness to changing paradigms in the closure of the sternum with rigid fixation slowly gaining credence.
Lets explore that in the next post....