If the bone edges at the site of a fracture are kept close together and held fairly still, they will heal together. This is because in most areas, bone is an active, vital component of your body, which is in a constant state of change. New bone is continuously being produced with old bone resorbed. Even when a broken bone heals slightly out of position, normal stresses on the bone will cause it to assume a more normal shape over time. This remarkable process does not always go as it should.
Several factors can affect the healing.
Problems such as a systematic disease or a vitamin deficiency can produce a significant delay in fracture repair, but this is mostly seen in the elderly or infirm. For a healthy adult in the prime of life, this kind of problem is rare. In any age group, when there is motion at a break, abnormal or delayed healing will result. Although casts are fairly easy to apply, they still allow some motion to occur at the edges of a break. Techniques pioneered in Switzerland have led to the use of bone screws and plates to keep bones in position.