What is hypertrophic callus?

Hypertrophic callus is a callus formation that is very fast and usually excessively strong. This can have various causes. However, the most common cause of excessive callus formation after a fracture is probably insufficient or inadequate immobilization of the fractured bone. This type of callus formation, in contrast to atrophic callus, shows good blood supply and thus the function of building up new bone tissue. Hypertrophic callus can be avoided or reduced by immobilising the fracture gap.

What is atrophic callus?

Atrophic callus is the term used to describe reduced callus formation. The reduced callus formation is often caused by greatly reduced blood flow in the area of the bone fracture. The cause of the reduced blood flow is usually to be found in the fact that dead bone fragments accumulate in the fracture gap.The reduced blood flow prevents the build-up of bone-forming cells, so that the fracture site remains unstable for a long time. In case of atrophic callus formation, surgery is often unavoidable. In this case, the bone pieces are removed from the fracture site and the bone is stabilized with plates and nails if necessary.

At what point can callus be seen in the X-ray image?

In the course of secondary (indirect) fracture healing, the bone goes through various phases of healing. The first of these phases consists of a slight shortening of the bone due to necrosis in the area of the fracture, and thus a widening of the fracture gap can be seen in the X-ray image. After about two weeks, the healing phase is completed.

The injury phase described above is followed by the inflammatory phase. This usually lasts another two to four weeks. The inflammatory phase is followed by the granulation phase, in which a soft callus is formed.

In most cases, the callus can be seen in the X-ray image four to six weeks after the fracture. In contrast, even if the callus is visible in the X-ray image, one can conclude that the fracture occurred at least four weeks ago. Callus appears in the X-ray image as a somewhat thickened, usually less strongly pigmented and blurredly limited expression between the ends of the fracture. In contrast, primary fracture healing does not result in callus formation, so that it is not visible in the X-ray image at any time.