Synchondrose

Synchondrose, or synchondrosis, is a type of cartilaginous joint in which two bones are joined by hyaline cartilage. It is classified as a primary cartilaginous joint and is typically considered an amphiarthrosis, allowing only limited movement.

In a synchondrosis, the bones are connected by a plate or bridge of hyaline cartilage rather than a fibrous capsule or synovial cavity. This arrangement provides stability while permitting some growth or bending. Many synchondroses are temporary: they allow longitudinal bone growth during development and later ossify to become a synostosis, leaving only a bony line.

Common examples include the epiphyseal plates (growth plates) of long bones, which enable lengthwise growth in children and adolescents; the basilar or spheno-occipital synchondrosis at the base of the skull, which typically fuses during adolescence; and the costochondral joints between ribs and their costal cartilages. Some other cranial base joints also belong to this category.

Clinical relevance centers on growth and development and on potential injuries or abnormal fusion. Persistent or premature ossification of synchondroses can affect bone growth and skeletal proportions. Since these joints lack a synovial cavity, they are not prone to the same types of inflammatory arthritis seen in synovial joints, but trauma or metabolic disorders can alter their normal pattern of ossification and fusion.