Osteopenia is a general term meaning increased radiolucency of bone in a radiograph. Is is solely used to describe a radiographic finding and does not imply an etiology. This finding, however, is subjective and dependent upon technical factors such as kVp, mAs, SID, and processing time and temperature. There are specific patterns of osseous resorption in tubular bones that are more objective findings and can be used to assess osteopenia. These locations include:
The objective features of osteopenia differ, depending upon whether the underlying disorder is chronic or acute in nature.
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Normally, the endosteal and subperiosteal surfaces of the cortex are well-defined and continuous and the remainder of the cortex is radiopaque and homogeneous in density. In chronic cortical osteopenia, the endosteal surfaces are ill-defined, and there are lucent striations running through the cortex, parallel to the shaft (B). These striations are known as intracortical tunneling. Endosteal bone resorption and intracortical tunneling can be seen with osteoporosis and osteomalacia. Generalized subperiosteal bone resorption is characteristic of hyperparathyroidism.
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Cancellous bone is made of primary and secondary trabeculae. The primary trabeculae are also known as stress trabeculae and are found along lines of stress. Secondary trabeculae are found perpendicular or oblique to the primary or stress trabeculae. Secondary trabeculae give spongiosa a fine, homogeneous appearance. With chronic osteopenia, there is resorption of the secondary trabeculae, leaving the primary trabeculae to stand out in relief. As bone is laid down upon the remaining primary trabeculae, they become coarse in appearance. Transverse, well-defined linear increased densities in tubular bones are known as bone bars (aka growth arrest lines) (see below). They are typically incidental findings.
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A |
B |
C |
Acute osteopenia has a different radiographic appearance and is primarily an abnormal finding of density. Motheaten, mottled, or patchy areas of decreased bone density are seen in spongiosa, especially periarticular regions (B, A is a normal for comparison). It may additionally involve cortical bone and have a permeative appearance (C).
Diffuse, chronic osteopenia can be caused by many metabolic and endocrine disorders.
The three major metabolic disorders include:
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(The above example demonstrates a fracture. Did you identify it?)
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© Copyright 1998, Robert A. Christman, D.P.M.
These articles and figures may not be published, reposted, or redistributed without permission from Dr. Christman.
This page was updated May 5, 1998.
courtesy Louis P. Zulli, D.P.M.
