Background: 209 patients with osteogenesis imperfecta type I, III and
IV were studied to provide data on the natural course of the disease u
ntil the end of the second decade. Results: Weight and length at birth
were normal in most cases of type I and IV, markedly reduced in type
III. Fractures and deformities at birth were most frequent in type III
. High fracture rates occurred in type III and IV up to 8-10 years of
age. Skeletal deformities developed primarily in the lower extremities
and the spine, again most frequently in type III. Radiological featur
es were - besides osteopenia - Wormian bones of the skull, pseudoarthr
oses, deformity of the pelvis, popcorn epiphyses (most frequent in typ
e III) and hyperplastic callus (most frequent in type IV). Longitudina
l growth of patients with type I was in the lower normal range, while
patients with type III and IV developed marked growth deficiency. Moto
r performance was not severely impaired in most cases of type I; howev
er, all type III patients and 71% of type IV patients were confined to
a wheelchair in later life. Conclusion: As defined, type I patients h
ad a mild clinical course until early adulthood. Type III and IV repre
sented a spectrum of severely affected patients. Although type IV pati
ents were less affected at birth, their postnatal course in some respe
cts resembled that of type III.