Fractures in patients with myopathies.

During the past 4 years, 15 fractures in 10 patients were encountered among 48 hospitalized patients with myopathies. The dominant sites were the femur (supracondylar) and humerus (subcapital). By assessing the total body potassium volume, bone mineral content, serum calcium, inorganic phosphorus, 25-OH vitamin D3, parathyroid hormone, and calcitonin, it is concluded that the proclivity to fracture in myopathic patients is caused by bone atrophy due to a lack of muscle tension related to decrease in muscle volume.