Synchondrosis

Synchondroses (singular: synchondrosis) are primary cartilaginous joints mainly found in the developing skeleton, but a few also persist in the mature skeleton as normal structures or as variants.

Structure

Synchondroses are cartilaginous unions between bone composed entirely of hyaline cartilage. Most exist between ossification centers of developing bones, and gradually ossify.

Immature skeletal examples

• growth plates
• synchondroses related to apophyses
• synchondroses of the pelvis e.g. ischiopubic synchondrosis
• spheno-occipital synchondrosis at the skull base
• manubriosternal synchondrosis

Mature skeletal examples

• first sternocostal joint between first rib and manubrium 
  • all other sternocostal joints are synovial joints
• petro-occipital synchondrosis at the skull base

Variant examples

• tarsal coalitions (cartilaginous type)
• os acromiale