Subgroups of Osteoporosis: From Different Points of View

Abstract

Osteoporosis may be localised to one or more skeletal regions i. e., focal or regional osteoporosis, as distinct from the classic generalised osteoporosis (systemic, global). The most important causative factors responsible for local bone loss are:

• Inactivity (immobilisation osteoporosis): The classical example is the regional osteoporosis which occurs when an extremity is immobilised either because of a fracture or a motor-neuron injury. The lack of use and movement results in increased osteoclastic resorption which, if sufficiently extensive, is also accompanied by hypercalciuria and hyperphosphaturia. On cessation of immobilisation and resumption of activity the process can be reversed and the bones normalised, especially those of children and young people.

• Complex Regional Pain Syndrome (CRPS, Sudeck’s disease, algodystrophy, sympathetic reflex dystrophy): This effects mainly the hands, knees, and ankles and is characterised by swelling, pain, hyperesthesias, and vasomotor reactions. This condition is dealt with extensively in Chap. 23.

• Transient (transitory) osteoporosis: Transient osteoporosis is a regional process first described in the pelvic bones in pregnant women. Since then, it has also been observed in knee and ankle joints in both young men and young women. The pain appears to start spontaneously without apparent prior trauma. The diagnosis is established by means of magnetic resonance imaging (MRI), which shows extensive edema of the bone marrow around the painful joint. Clinically, the process is self-limiting with complete restitution within a year.