The injury phase is the first and shortest phase of secondary fracture healing. It overlaps with the second phase, the inflammatory phase. During the injury phase, fracture fragments can injure internal organs in extreme cases.
What is the injury phase?
The injury phase is the first and shortest phase of secondary fracture healing. A fracture can be primary and direct or secondary and therefore indirect. In a primary fracture, the fracture fragments are in contact with each other or at least not much more than a millimeter apart. In a secondary fracture, on the other hand, there is a gap that must grow together during fracture healing. During secondary fracture healing, cells such as osteoblasts bridge the gap by forming a so-called callus of mesenchymal cells, which is mineralized with calcium in the late stages of fracture healing and thus stabilized. The healing of indirect fractures is called secondary fracture healing. It consists of five different phases. The injury phase is the first phase of the healing process. The following phases are the inflammation phase, the granulation phase, the callus hardening phase, and the remodeling phase, which consists of modeling and remodeling of the bone.
Function and task
Human bones are alive. They are accompanied by permanent growth and remodeling processes, which are also summarized as ossification. Osteoblasts build bone and osteoclasts remove bone tissue. In this way, bones can adapt to changing conditions. After fractures, they can grow back together in this way and even regenerate completely. In primary fractures, the periosteum is not destroyed and the fracture fragments can be joined by capillary-rich connective tissue. In secondary fracture healing more complex. Regeneration occurs in five phases that initiate callus formation to bridge the gap. The first phase of secondary fracture healing is the injury phase. Fractures result from a direct or indirect force that overstresses the elasticity or strength of the bone. The bone is completely severed because it can no longer withstand the forces applied. Two or more fragments form and the bone loses its stabilizing function. The injury or fracture phase begins when the force is applied. It ends only when there are no more forces acting on the bone or surrounding tissue. The affected area absorbs all the energy of the force. The injury phase is the shortest phase of secondary fracture healing and usually lasts no longer than a few seconds. During this phase, the extent, angle, and exact location of the fracture is decided. The cortical bone, bone marrow, periosteum and surrounding tissues are severed or at least injured during the injury phase. Subsequently, a hematoma forms in the fracture gap. It bleeds into the fracture because numerous blood vessels of the immediate surroundings have been destroyed. The hematoma spreads along the fissure. At this point, the fracture phase overlaps or merges with the inflammatory phase.
Diseases and complaints
Various complications can occur during the injury phase of secondary fracture healing. For example, depending on the location and severity of the force, the fractured bone fragments may damage organs in the immediate vicinity, causing severe internal bleeding. Apart from this extreme case, the fracture ends can move more or less far out of their physiological position depending on the angle of the violent impact. They must then be returned to a position that is as exactly anatomically correct as possible, otherwise the accompanying damage will rapidly worsen or the fractured bones will grow together in a malposition. The repositioned bones must also be prevented from leaving the anatomically correct position again during healing. Fractures are more common in diseases such as brittle bone disease or osteoporosis. Those affected by brittle bone disease suffer from a mutation on chromosomes 7 and 17. This genetic material codes for the collagen type I protein. The protein is an essential component of connective tissue. Since connective tissue plays a crucial role in bone formation, affected individuals suffer from abnormally structured bones with high brittleness.Patients with osteoporosis also suffer more frequently from bone fractures. This disease is characterized by reduced bone density. Those affected suffer from an imbalance of bone-building osteoblasts and bone-eroding osteoclasts. Thus, an imbalance occurs during the permanent demineralization and remineralization of the bone substance. Bone mass is degraded by osteoclasts to a greater extent than osteoblasts produce bone mass. A slight imbalance is physiological, especially in old age. Bones thus become more brittle in the later decades of life due to age physiology than they are at the beginning of life. However, in patients of osteoporosis, there is a pathological imbalance in the activity of osteoblasts and osteoclasts.