Diagnosis of Osteoporotic Vertebral Fractures: Importance of Recognition and Description by Radiologists

Leon Lenchik; Lee F. Rogers; Pierre D. Delmas; Harry K. Genant

Disclosures

Am J Roentgenol. 2004;183(4) 

In This Article

Rationale for Adapting the Genant Method to Clinical Practice

In Genant's method,[60] the severity of a fracture is assessed by visual determination of the extent of a vertebral height reduction and morphologic change, and vertebral fractures are differentiated from other nonfracture deformities. The approximate degree of height reduction determines the assignment of grades to a vertebra. Unlike the other approaches, the type of the deformity (i.e., wedge, biconcavity, or crush) is not linked to the grading. In addition to height reductions, careful attention is given to alterations in the shape and configuration of the vertebra relative to adjacent vertebrae and expected normal appearances. These features add a qualitative aspect to the interpretation and render this method less readily definable as either qualitative or quantitative.

The main reasons that this method is ideally suited to serve as a basis for a standardized interpretation of vertebral fractures in clinical practice are the following: It is less time-intensive and cumbersome than morphometric methods (i.e., in which all vertebral dimensions are measured), it is more accurate than nonstandardized qualitative assessment,[19] it is highly reproducible,[61,62] and it is already well known to most clinicians who have an interest in osteoporosis.

More Practical for Clinical Practice Than Morphometry

Many standardized approaches to describing vertebral fractures have been used in research.[55–60] Can any of these approaches be easily adapted to clinical practice? The answer seems largely dependent on whether measurement of vertebral dimensions is required. It is unlikely that such measurements would be practical in most clinical settings. Ideally, the standardized assessment would assign distinct categories (or grades) to vertebral fractures according to their severity in a reproducible manner without making measurements of vertebral dimensions. The Genant method[60] accomplishes just that.

More Accurate Than Nonstandardized Qualitative Assessment

Why not use a purely qualitative approach to vertebral fracture diagnosis? The answer is because assessment of vertebral fractures using standardized grading schemes has been found to be more reproducible and generalizable than the inspection of radiographs without specific criteria for fracture diagnosis.[19,63,64] In the absence of distinct characteristics of fracture, a reviewer using a solely qualitative approach could rather arbitrarily consider a mild wedge deformity normal, anomalous, or fractured. In such a case, well-defined quantitative criteria may be useful. This possible arbitrary interpretation explains in part why standardized approaches have been found to be such valid research tools.[1,15,57–60]

High Reproducibility

The rationale for adapting this method to clinical practice is further supported by its high reproducibility in evaluating both prevalent and incident vertebral fractures. In the prevalent vertebral fracture study of 400 postmenopausal women with low BMD,[61] the interobserver agreement was about 94% for the dichotomous fracture–nonfracture diagnosis and 91% using the whole-grading scale. In the study of incident vertebral fractures in 335 women with low BMD who underwent follow-up radiography 12 months after the initial examination,[62] the kappa scores among the three reviewers were good, ranging from 0.80 to 0.84.

Limitations of the Genant Method

The Genant method has several limitations that may also apply to the other standardized approaches. For example, from morphometric data on healthy subjects, we know that vertebrae in the mid thoracic spine and in the thoracolumbar junction are slightly more wedged than in other regions of the spine. As a result, normal variations may be misinterpreted as mild vertebral deformities. The same findings apply to a lesser extent to the lumbar spine, in which some degree of biconcavity is frequently seen. Another possible limitation is that the diagnosis of mild vertebral fractures may be quite subjective and these fractures may be unrelated to osteoporosis.[65] However, mild fractures detected with the Genant method are associated with a lower BMD than normal and predict future vertebral fractures, although to a lesser extent than moderate or severe fractures.[66]

For these reasons and despite the stated limitations, the Genant method should be adopted by radiologists as the standard for reporting of osteoporotic vertebral fractures. The joint initiative of the IOF and the European Society of Skeletal Radiology has endorsed this approach. We hope that other professional organizations will follow their lead.

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