Radiology of Osteogenesis Imperfecta, Rickets and Other Bony Fragility States

Abstract

This section gives an overview of radiological findings in bony fragility states, with a special focus on osteogenesis imperfecta (OI) and rickets. Conventional radiological assessment of bone density is inaccurate and imprecise and only reliably detects severe osteopaenia. However, other aspects of bone structure and morphology can be assessed, and it is possible to distinguish between osteopaenic and osteomalacic states. OI is a heterogeneous group of disorders of type 1 collagen formation and processing that are characterised by varying degrees of bony fragility, with presentations varying from perinatal lethality to asymptomatic. Radiological diagnosis of severe forms is usually straightforward, but that of milder disease may be challenging because specific features are often absent. However, a multidisciplinary approach is usually successful. Features of OI, including Wormian bones, skull base deformities, vertebral involvement and long bone fractures and deformities, are reviewed in this section. Rickets is best defined as a disorder of the growth plate characterised by the impaired apoptosis of hypertrophied chondrocytes. Vitamin D deficiency is a common cause of rickets. The patho-anatomical basis of radiological findings in rickets is reviewed and illustrated. Rickets is frequently accompanied by hyperparathyroidism and osteomalacia. Rickets used to be classified as calciopaenic or phosphopaenic but is now referred to as parathyroid hormone or fibroblast growth factor 23 mediated, respectively [1]. The radiological features of the two forms are reviewed.

Imaging Findings of Metabolic Bone Disease

“…Any problem in the bone mineralization pathway, including insufficient calcium or phosphate levels, abnormal pH, or the presence of inhibitors of mineralization, can result in osteomalacia (Fig 3). Causes of rickets and osteomalacia are listed in Table 1 (23)(24)(25). The radiographic findings observed in rickets are listed in Table 2 and illustrated in Figure 4.…”

“…The findings are observed on the metaphyseal side of the growth plate because unmineralized osteoid is concentrated along the metaphyseal side of the growth plate. Failure of mineralization leads to disorganized chondrocyte growth, and hypophosphatemia leads to impaired apoptosis of hypertrophic chondrocytes, which results in excessively long cartilage cell columns and the radiographic findings of widening of the growth plate and cupping and fraying of the metaphyses (23)(24)(25)(26).…”

“…Some of the common locations of Looser zones are similar to those of stress fractures, such as the inner margin of the femoral neck or the pubic rami. However, Looser zones also occur in non-weight-bearing bones, which are atypical locations for stress fractures, such as the lateral aspect of the femoral shaft at the level of the lesser trochanter, the ischium, the iliac wing, and the lateral scapula (23,24).…”

“…In the infantile and childhood forms, there can be craniosynostosis; and in the childhood form, characteristic "tongues" of lucency extend from the growth plate to the metaphysis. Skeletal findings can improve after enzyme replacement therapy with asfotase alfa, a recently developed recombinant tissue-nonspecific alkaline phosphatase (Fig 8) (23,24,28).…”

Vitamin D deficiency in individuals with a spinal cord injury: a literature review

“…An adequate vitamin D status has been shown to be important for the elderly, 1,2 children 3,4 and athletes. 5 It has been suggested that a vitamin D deficiency might be related to a number of health issues such as rickets, 6,7 osteoporosis, 8 osteomalacia, 9 cardiovascular diseases, 10 hypertension, 11 multiple sclerosis, Parkinson's and Alzheimer's disease 12 and cancer. 11,13 In addition, an insufficient vitamin D status might affect neuromuscular function 14 that could lead to injuries and might also generate a higher risk for falls in the elderly.…”