Introduction

This chapter deals with pediatric disorders which are characterized by increased bone fragility and decreased bone mass. Compared with adults, such diseases are relatively rare in children, but may have devastating consequences. Osteoporosis can occur as a primary bone disorder or may be secondary to other diseases and/or their treatment (Table 13.1). The primary forms of childhood osteoporosis comprise osteogenesis imperfecta and idiopathic juvenile osteoporosis. Secondary pediatric osteoporosis is most frequently seen as a consequence of immobilization and of long-term steroid treatment in a variety of chronic diseases.

Osteogenesis imperfecta

Osteogenesis imperfecta (OI), also called brittle bone disease, is a hereditary form of osteoporosis. In many patients the disease is due to abnormalities in collagen type I. Therefore, the disease manifests itself not only in bone, but also in other tissues that contain collagen type I, such as skin, teeth and sclerae. OI is thought to affect between 1/10000 and 1/15000 individuals of all racial and ethnic origins (Byers & Steiner, 1992).

Clinical presentation

Family history

In most familial cases of OI, heredity follows an autosomal dominant pattern. However, new mutations are frequent, especially in the more severe forms. There may also be germline mosaicism for OI mutations, so that unaffected parents can have more than one affected child (Rowe & Shapiro, 1998).