There are several classifications for osteo porosis. For many years it has been separated into primary osteoporosis (osteporosis without associated disease), and secondary osteoporosis (with associated conditions) (Fig. 18.17).
A separate classification has been proposed in which primary osteoporosis is subdivided into type I (postmenopausal) and type II (senile). The type-I variant predominantly involved trabecular bone, occurs at an early age, is much more frequent in women, and is often complicated by vertebral fractures. The type-II variant occurs in men and women, is more common in the older age group, and is often complicated by hip fractures. Some workers have suggested that different pathogenic events may be involved in these two forms: type I due primarily to oestrogen deficiency, and type II due to a combination of impaired calcium absorption from the gut and impaired osteoblast function.
