Aug 26, 2022 – Healing a broken bone isn’t always a straightforward process of putting on a cast and waiting for the body to do its work over time. The many materials that make up our bones have different density and interact in many ways that affect whether or not the fracture heals properly.
A fracture that is not treated properly is called non-healing and takes a long time bone, like the shin bone, can be disabled. Doctors can’t always tell when a misunion occurs, let alone how to predict how early it is likely to occur. But research into bone imaging techniques is on track to change that and give clinicians a glimpse into the future to help them find problems early.
Mechanical engineering researchers at Lehigh University in Bethlehem, Pennsylvania, are using bone imaging and virtual mechanical tests to develop more accurate model of the healing process.
The hypothetical model could help clinicians recognize bone abnormalities from the healthy healing process so they can intervene sooner. The key is to better understand the physical process in the healing area where the fracture is repaired.
Inside the cast
The healing process begins when the body recognizes the fracture and sends immune cells to cause it ignition. Swelling is a warning signal for the body to stop using the affected part.
Blood cells also collect around the injury, and this mass of cells – a hematoma, or a blood clot Fills the void in the break. Over the next week, a type of soft bone called a callus gradually replaces the blood clot and holds the bone together, although it’s not strong enough to start using the bone yet. Several weeks later, callus It has time to harden, then the hard bone begins to replace the hard callus.
But it’s hard to see how well these late stages occur on an X-ray, as hard callus and tough bone look so much alike. Engineers are working to understand the mechanical properties of the bone and the callus, such as mass and density, so they can better predict when the hard bone has completely replaced the screw. Expecting it too early can hinder the healing process if a person is using the bone normally before it has completely healed.
Previous computer models were unable to accurately distinguish a hard callus from hard bone, in large part because the callus itself is composed of different types of tissue with different physical properties.
But this new research is based on testing the stress on bones during a sprain. The researchers fed test results and corresponding CT images into a computer to model the healing process. The brighter areas in the image represent stiffer, harder bone, so their work helped the investigators figure out when the material stopped being callus and changed into the bone. Knowing this break point can help determine when a nonunion occurs sooner, which in turn can help doctors better understand how and why the healing process fails so they can help.