Nonunion
Encyclopedia
Nonunion is permanent failure of healing
following a broken bone.
Nonunion is a serious complication
of a fracture and may occur when the fracture moves too much, has a poor blood supply or gets infected. Patients who smoke have a higher incidence of nonunion. The normal process of bone healing
is interrupted or stalled. In some cases a pseudo-joint (pseudarthrosis
) develops between the two fragments with cartilage
formation and a joint cavity. More commonly the tissue between the ununited fragments is scar tissue.
Since the process of bone healing is quite variable, a nonunion may go on to heal without intervention in a very few cases. In general, if a nonunion is still evident at 6 months post injury it will remain unhealed without specific treatment, usually orthopedic surgery
. A non-union which does go on to heal is called a delayed union.
plate of the fractured bone shows a persistent radiolucent line at the fracture. Callus
formation may be evident but callus does not bridge across the fracture. If there is doubt about the interpretation of the Xray, stress Xrays, tomograms or CT scan may be used to make sure.
causes (e.g. impaired blood supply to the bone fragments) or metabolic causes (e.g. diabetes or smoking
). Failure of initial union, for example when bone fragments are separated by soft tissue
may also lead to atrophic non-union. Atrophic non-union can be treated by improving fixation, removing the end layer of bone to provide raw ends for healing, and the use of bone grafts.
within 3 months, but the treatment may continue for many months beyond that.
Bone healing
Bone healing, or fracture healing, is a proliferative physiological process in which the body facilitates the repair of a bone fracture....
following a broken bone.
Nonunion is a serious complication
Complication (medicine)
Complication, in medicine, is an unfavorable evolution of a disease, a health condition or a medical treatment. The disease can become worse in its severity or show a higher number of signs, symptoms or new pathological changes, become widespread throughout the body or affect other organ systems. A...
of a fracture and may occur when the fracture moves too much, has a poor blood supply or gets infected. Patients who smoke have a higher incidence of nonunion. The normal process of bone healing
Bone healing
Bone healing, or fracture healing, is a proliferative physiological process in which the body facilitates the repair of a bone fracture....
is interrupted or stalled. In some cases a pseudo-joint (pseudarthrosis
Pseudarthrosis
Pseudarthrosis is the movement of a bone at the location of a fracture resulting from inadequate healing of the fracture.Pseudarthrosis can also result from a developmental failure.-Etymology:...
) develops between the two fragments with cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
formation and a joint cavity. More commonly the tissue between the ununited fragments is scar tissue.
Since the process of bone healing is quite variable, a nonunion may go on to heal without intervention in a very few cases. In general, if a nonunion is still evident at 6 months post injury it will remain unhealed without specific treatment, usually orthopedic surgery
Orthopedic surgery
Orthopedic surgery or orthopedics is the branch of surgery concerned with conditions involving the musculoskeletal system...
. A non-union which does go on to heal is called a delayed union.
Clinical features
A history of a broken bone is usually apparent. The patient complains of persistent pain at the fracture site and may also notice abnormal movement or clicking at the level of the fracture. An x-rayX-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
plate of the fractured bone shows a persistent radiolucent line at the fracture. Callus
Fibrocartilage callus
A fibrocartilage callus is a temporary formation of fibroblasts and chondroblasts which forms at the area of a bone fracture as the bone attempts to heal itself...
formation may be evident but callus does not bridge across the fracture. If there is doubt about the interpretation of the Xray, stress Xrays, tomograms or CT scan may be used to make sure.
Hypertrophic non-union
Callus is formed, but the bone fractures have not joined. This can be due to inadequate fixation of the fracture, and treated with rigid immobilisation.Atrophic non-union
No callus is formed. This is often due to impaired bony healing, for example due to vascularVascular
Vascular in zoology and medicine means "related to blood vessels", which are part of the circulatory system. An organ or tissue that is vascularized is heavily endowed with blood vessels and thus richly supplied with blood....
causes (e.g. impaired blood supply to the bone fragments) or metabolic causes (e.g. diabetes or smoking
Smoking
Smoking is a practice in which a substance, most commonly tobacco or cannabis, is burned and the smoke is tasted or inhaled. This is primarily practised as a route of administration for recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them...
). Failure of initial union, for example when bone fragments are separated by soft tissue
Soft tissue
In anatomy, the term soft tissue refers to tissues that connect, support, or surround other structures and organs of the body, not being bone. Soft tissue includes tendons, ligaments, fascia, skin, fibrous tissues, fat, and synovial membranes , and muscles, nerves and blood vessels .It is sometimes...
may also lead to atrophic non-union. Atrophic non-union can be treated by improving fixation, removing the end layer of bone to provide raw ends for healing, and the use of bone grafts.
Untreated prognosis
By definition, a nonunion will not heal if left alone. Therefore the patient's symptoms will not be improved and the function of the limb will remain impaired. It will be painful to bear weight on it and it may be deformed or unstable.Treatment
Surgical treatment includes removal of all scar tissue from between the fracture fragments, immobilization of the fracture with metal plates, rods and or pins and bone graft. In simple cases healing may be evident within 3 months. Ilizarov revolutionized the treatment of recalcitrant nonunions demonstrating that the affected area of the bone could be removed, the fresh ends "docked" and the remaining bone lengthened using an external fixator device. The time course of healing after such treatment is longer than normal bone healing. Usually there are signs of unionBone healing
Bone healing, or fracture healing, is a proliferative physiological process in which the body facilitates the repair of a bone fracture....
within 3 months, but the treatment may continue for many months beyond that.