Osteodystrophy

Albright's hereditary osteodystrophy, which is also known as pseudohypoparathyroidism, occurs in patients with a characteristic phenotype (short stature, round face, short neck and shortening of metacarpal bones) and low serum calcium and high serum phosphorus levels consistent with hypoparathyroidism. In these patients the parathyroid glands are intrinsically normal, but the end-organ (renal) response to parathyroid hormone is abnormal. Typical radiographic features are short metacarpals, metatarsals and phalanges, exostoses, cone epiphyses, and wide bones. Basal ganglion calcification and thickening of the calvaria are also seen.

Renal osteodystrophy refers to bone disease in patients with chronic renal failure. Two main mechanisms are thought to be responsible for the bone abnormalities, and these factors may act in concert: secondary hyperparathyroidism and abnormal vitamin D metabolism. The pathological and radiological findings are those related to hyperparathyroidism, rickets and osteomalacia, osteoporosis, and soft tissue and vascular calcification.

Osteosclerosis is well known to occur in renal osteodystrophy, especially in the pelvis, ribs and vertebral bodies (rugger jersey spine). Periosteal bone formation in patients with renal osteodystrophy is termed periosteal neostosis and is seen most commonly in patients with hyperparathyroidism.

Rickets and osteomalacia produce the radiographic features of osteopenia, deformities, Loosers zones, irregularity and widening of the growth plate, and poor definition of the epiphysis.

A slipped epiphysis, especially a slipped capital femoral epiphysis, may occur in renal osteodystrophy and may be preceded by three signs: bilateral subperiosteal erosion on the medial aspect of the femoral neck, increase in width of the cartilaginous growth plate and bilateral coxa vara.

Pathologic fractures (III) and calcification of soft tissue and vascular structures are recognized complications of renal osteodystrophy. In addition, some patients may develop secondary gouty arthritis or oxalosis.

Hepatic osteodystrophy, or metabolic bone disease, is of multifactorial causation and occurs as a complication of chronic disorders involving the biliary ducts or hepatocellular disorders. Both osteoporosis and osteomalacia occur in this disorder sometimes with pseudofractures. Bone pain, tenderness and fractures may be significant. Hypertrophic osteoarthropathy has also been reported but is not common.

Sudeck's atrophy is discussed under the name reflex sympathetic dystrophy.

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