Pseudarthrosis
| Pseudarthrosis | |
|---|---|
 |
|
| Hypertrophic nonunion of the tibia | |
| Classification and external resources | |
| Specialty | rheumatology |
| ICD-10 | M84.1, M96.0 |
| MeSH | C21.866.404.468.627 |
Pseudarthrosis (commonly referred to as a nonunion or false joint) is a bone fracture that has no chance of mending without intervention. In pseudarthrosis the body perceives bone fragments as separate bones and does not attempt to unite them. Often this is the result of inadequate healing after the fracture, though it can also be the result of a developmental failure. In the U.S., FDA guidelines allow a period of 9 months for fracture union, after which intervention is considered to facilitate union.
The Greek stem "pseudo-" means false and "arthrosis" means joint. Pseudarthrosis, then, is a false joint. In the case of a "non-union", a fracture that does not heal, this is often evidenced by the obliteration of the medullary cavity of a long bone at the site of the non union. This non union is not a true joint, and has no ligamentous support, but often has motion, and remodels into a rounded end that looks like a true joint.
Judet and Judet, Muller, Weber and Cech, and others classified nonunions into two types according to the viability of the ends of the fragments: Hypervascular nonunions and avascular nonunions.
Hypervascular nonunions are subdivided as:
Avascular nonunions are subdivided as:
Paley classified tibial nonunions based on clinical and roentgenographic characteristics as Type A (Bone loss of less than 1 cm) and Type B (Bone loss of more than 1 cm). Type A is subclassified as Type A:1 Lax type; Lax nonunion have limited mobility and usually some fixed deformity, Type A:2:1 stiff nonunion without deformity and Type A:2:2 stiff nonunion with a deformity. Type B subclassified as Type B:1 bony defect with no shortening, Type B:2 shortening with no gap and Type B:3 there is both gap and shortening.
The point of movement can be treated with electrical stimulations that hopefully will trigger the bone cells to form the hydroxyapatite structure that keeps bones from bending too much. More recently, non-unions are treated by bone grafting, internal fixation, and external fixation, including a technique pioneered by Ilizarov, used to compress the bones at the site of the fracture. Ilizarov originally used bicycle spokes; the modern Taylor Spatial Frame is similar.
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