[Muscular involvement in osteomalacia: clinical, hystoenzymologic and ultrastructural study in 10 cases]

Osteomalacic myopathies are rare. They can prevail, however, and occur before bone abnormalities. The diagnosis must rest on clinical observation since the histopathologic images are not specific. On the other hand the demonstration of muscular weakness is very frequent during osteomalacia. In fact two types of manifestations correspond to the same anatomopathologic lesions. These are myopathic changes observed also during light microscopy, histoenzymologic and ultrastructural examination in the 10 patients examined. On the basis of these morphologic changes, muscular involvement can be considered to be part of the osteomalacia syndrome. The contribution of various factors including secondary hyperparathyroidism, vitamin D metabolism disorders, and phosphorus depletion is discussed. It is probable that many of them act together, causing reversible changes in muscular fibers. The intimate mechanisms of these changes are unknown.