One important entity to distinguish from osteochondritis dessicans is normal irregularity of the
ossification centers. Irregular ossification typically affects the posterolateral femoral condyle and usually occurs in children less than 10 years old, although there is slight variation depending on sex.
Scintigraphy study reports no alterations, while magnetic resonance reveals multiple
ossification centers of the femoral head with normal signal intensity and decrease in epiphysis size (6).
(12,13) Type I, or os tibiale externum, occurs when an
ossification center forms a sesamoid bone within the tibialis posterior tendon, near the navicular insertion.
Ebraheim, "Biomechanical rationale of ossification of the secondary
ossification center on apophyseal bony ring fracture: a biomechanical study," Clinical Biomechanics, vol.
The timing of appearance of elbow secondary
ossification centers shows considerable diversity regarding age, gender, and race.
The interscalar septum and the bone between the cochlea and the vestibule develop from the
ossification centers. Partly missing this bone suggests over-resorption, resulting in a defect of the cartilaginous capsule and a failure of ossification [6].
Our case had similar radiographic findings with at least one missing pedicle at the level of the midcervical spine along with obvious cervical kyphosis and incomplete/absent
ossification centers (Figure 3).
possessed significantly fewer
ossification centers in hindlimb phalanges and caudal vertebra.
The actual etiology of this condition which is thought to arise from defect of fusion of two primary
ossification centers of the clavicula is not known exactly.
It was established that
ossification centers in the cartilaginous anlages of fore limbs appear a day earlier than in the hind ones, and the process of ossification is slower.