Abnormal bone ossification

What it means

Any anomaly in the formation of bone or of a bony substance, or the conversion of fibrous tissue or of cartilage into bone or a bony substance.

All bones are formed by the replacement by osteocytes of mesenchyme-derived connective tissue. Intramembranous ossification refers to the direct replacement of primitive mesenchyme with bone, and is responsible for bones such as the calvarium (e.g., frontals, parietals, interparietal) and the clavicula. In endochondral ossification, the mesenchyme differentiates into a cartilaginous intermediate, which serves as a template (anlange) that is subsequently removed and replaced by bone. Most bones are formed via endochondral ossification, including those at the base of the skull, the vertebral column, pectoral and pelvic regions and long bones of the extremities. A reduction in the amount of mineralized bone compared with that expected for a given developmental age. In clinicakl parlance, reduced ossification and delayed ossification are often used synonymously, but in principle a bone delayed ossification in a child can display normal ossification at a later developmental stage. The HPO will therefore treat poor, reduced, and decreased officiation as synonymous, and delayed ossification as a specific kind of reduced ossification.

Rare diseases that can present with this20

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Abnormal bone maturation