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

¹ Department of Radiology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1088.
² Present address: The University of Arizona Health Sciences Center, 1501 N Campbell Ave., PO Box 245067, Tucson, AZ 85724-5067.
³ Department of Medicine, University Claude Bernard and INSERM Research Unit, Lyon, France.
⁴ Department of Radiology, University of California School of Medicine, San Francisco, CA.

Received September 9, 2003; accepted after revision March 24, 2004.

 
Address correspondence to L. Lenchik (llenchik{at}wfubmc.edu).

Introduction

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
Osteoporosis is a major public health concern. Recent evidence from clinical and epidemiologic trials on osteoporosis has increased the urgency for accurate diagnosis of vertebral fractures. Despite the fact that vertebral fractures are very common [1–8] and are associated with decreased quality of life [9–16], they are frequently undetected by clinicians [17, 18] and underdiagnosed by radiologists [19, 20]. We review the clinical consequences of vertebral fractures and explore the reasons why these fractures often evade diagnosis. More important, we urge radiologists to play a more active role in the diagnosis of vertebral fractures. Because many of the clinical consequences of vertebral fractures are preventable with prompt pharmacologic intervention, there is increasing rationale for accurate and unambiguous diagnosis of these fractures by radiologists. With an unambiguous approach to reporting of vertebral fractures, radiologists can make a significant contribution to the appropriate care of patients with osteoporosis.

Frequency of Vertebral Fractures

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
According to the National Osteoporosis Foundation, 30 million American women and 14 million men are affected by osteopenia or osteoporosis [21]. All are at an increased risk for fracture, and some have already experienced fracture [22, 23]. In the United Sates, the lifetime risk of osteoporotic fracture is 40% in white women and 13% in white men [7, 8]. Patients with osteoporosis commonly fracture their vertebrae, proximal femur, distal radius, or proximal humerus; the most common site is the vertebral body [6, 8]. With approximately 700,000 cases each year in the United States, vertebral fractures account for nearly half of all osteoporotic fractures and are at least twice as common as hip fractures [6].

As with most other osteoporotic fractures, the incidence of vertebral fractures increases with age. In the United States, the incidence rate for symptomatic vertebral fractures in white women under 45 years old is 0.2 per 1,000 person-years compared with 1.2 per 1,000 person-years after 85 years old [24]. Because many vertebral fractures are asymptomatic, these rates grossly underestimate the scope of the problem. More important, vertebral fractures generally occur earlier in life than hip fractures. In a large cross-sectional study in Europe, on the basis of standardized radiologic evaluation, the prevalence of vertebral fractures in men and women age 50 and older varied from 10% to 24% [1]. In both sexes, the prevalence of vertebral fractures increases dramatically with age [1, 2]. In one study [2], the prevalence in women increased from 5% to 50% between 50 and 85 years old. The epidemiology of vertebral fracture in nonwhites has not been thoroughly studied, but it appears that Hispanic and African American women have lower fracture rates than whites [25, 26]. Yet, the impact of vertebral fractures is best measured, not on the basis of their frequency, but rather on their effect on the patient's quality of life.

Clinical Consequences of Vertebral Fractures

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
Increasing evidence [9–16] indicates that quality of life is diminished in patients with vertebral fractures. Loss of physical function in patients after vertebral fracture is substantial and comparable to that of hip fracture [9–11]. Patients with vertebral fractures often have difficulty with activities of daily living such as rising from a chair, bathing, dressing, cooking, climbing stairs, and walking [9–11]. In addition, vertebral fractures are commonly associated with chronic back pain, limitation of spine mobility, reduction in pulmonary function, and social isolation [12–16].

Even asymptomatic vertebral fractures have significant consequences for the patient because of the increased risk of future fractures that may be symptomatic. Existence of one previous vertebral fracture increases the risk for subsequent vertebral fracture approximately fivefold and the risk of hip fracture approximately threefold [27–29]. Furthermore, the mortality rate associated with vertebral fractures is increased for both symptomatic (i.e., clinical) and asymptomatic (i.e., radiographic) fractures [30–34] and, in some studies [30, 35], approaches that for hip fracture.

Treatment of Patients with Vertebral Fractures

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
The clinical treatment of patients with vertebral fracture is largely determined by the presence of signs and symptoms, in particular pain. The management of pain may include physical modalities (i.e., heat, cold, ultrasound, or electrical stimulation), physical rehabilitation and exercise programs, pharmacologic therapy, nerve blocks, vertebroplasty and kyphoplasty, or surgery. Pharmacologic therapy aimed at prevention of future osteoporotic fractures is vital for patients with vertebral fractures and is applicable to both symptomatic and asymptomatic fractures.

It is in the accurate diagnosis of asymptomatic vertebral fractures that radiologists make perhaps the most significant contribution to patient care. More specifically, the diagnosis of vertebral fracture by radiologists impacts patient treatment by enabling the diagnosis of osteoporosis, helping select patients for pharmacologic therapy, improving the ability to assess risk of future fracture, and providing rationale for bone mineral density (BMD) measurement.

Diagnosis of Osteoporosis
Many clinicians consider the presence of a fragility fracture as sufficient for diagnosis of osteoporosis regardless of the patient's BMD. Although bone densitometry is useful for assessing disease severity and monitoring therapy in patients with fractures, densitometry is not essential for the diagnosis of osteoporosis in this setting. Exclusion of malignancy and trauma as the cause of fracture and biochemical evaluation of serum or urine or both to exclude secondary causes for bone fragility are required. After the diagnosis of osteoporosis is made, most patients are offered pharmacologic therapy aimed at preventing future fractures. Thus, the ability to make the diagnosis of osteoporosis on the basis of the presence of vertebral fracture is not trivial.

Selection of Patients for Therapy
Increasing evidence [36–42] justifies offering pharmacologic therapy for osteoporosis to patients with vertebral fracture after nonosteoporotic causes (e.g., malignancy and trauma) have been excluded.

The presence of vertebral fractures has been one of the most common criteria for selecting individuals for clinical trials on osteoporosis therapy [36–42]. Individuals with existing vertebral fractures have a much higher incidence of subsequent fractures than those without fractures and have been used in most clinical trials on osteoporosis therapy [36–42]. Pharmacologic therapy for osteoporosis is effective in patients with vertebral fractures: trials with alendronate, calcitonin, raloxifene, risedronate, and teriparatide have shown 30–50% reductions in fracture incidence [36–42]. Although these agents also reduce the risk of vertebral fracture in patients with low BMD but without prevalent fractures, the absolute risk reduction is greater in those with prevalent vertebral fractures [36–42]. Thus, the decision as to whether a patient is a candidate for therapeutic intervention is based not only on the results of a bone densitometry examination but also on the presence of a vertebral fracture.

Improving the Ability to Predict Fracture Risk
The presence of vertebral fracture is an important factor in predicting the risk of future fractures. Clinical guidelines, including those from the National Osteoporosis Foundation [43] and the International Osteoporosis Foundation (IOF), [44] state that vertebral fractures are the key risk factor, other than low BMD, in the assessment of future fracture risk. The importance of vertebral fractures is also recognized in the World Health Organization (WHO) classification criteria for osteoporosis [45]. The WHO criteria define "severe osteoporosis" as low bone mass "in the presence of one or more fragility fractures."

Risk assessment for individual patients can be improved by combining BMD results and vertebral fracture assessment. For example, a woman with low BMD and one vertebral fracture has 25 times the risk of a patient with normal BMD and no fracture [46]. Thus, the diagnosis of vertebral fractures by radiologists helps clinicians and their patients to be better informed about the overall fracture risk.

Indication for Bone Densitometry
Many insurance carriers (including the Centers for Medicare and Medicaid Services) consider vertebral fractures as one of the indications for bone densitometry. Practically, the approach of measuring BMD even in patients with vertebral fractures has merit because patients with low bone density and vertebral fractures are not only at the highest risk for future fractures but are also most likely to benefit from pharmacologic therapy.

Diagnosis of Vertebral Fracture

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
The diagnosis of a vertebral fracture may be suspected on clinical evaluation and confirmed with radiography. However, unlike other fractures, vertebral fractures are commonly present on radiographs obtained for other reasons in patients who may not show signs or symptoms suggestive of fracture.

Clinical Diagnosis
Although vertebral fractures are common in postmenopausal women and older men, they are often difficult to identify clinically (i.e., without radiographs). Only about one in four vertebral fractures is clinically recognized [47]. The lack of recognition is due to both the absence of symptoms and the difficulty in determining the cause of symptoms. Because most episodes of back pain are not related to vertebral fractures, vertebral fractures are not commonly suspected in patients reporting back pain, unless the back pain is associated with trauma. Height loss, another indicator of vertebral fractures, is also difficult to assess clinically [48, 49]. Some height loss is expected with aging, because of compression of the intervertebral disks. Studies [48, 49] have concluded that height loss is an unreliable indicator of fracture status until it exceeds 4 cm. Kyphosis in the elderly is associated with vertebral fracture but is difficult to measure in a clinical setting without the use of radiography [50].

For these reasons, vertebral fractures are not commonly considered in the clinical evaluation of patients. Even when patients are being evaluated for the presence of osteoporosis, it is far less common for them to be referred for spine radiographs than for bone densitometry.

Radiologic Diagnosis
Vertebral fractures suspected at clinical evaluation require radiologic confirmation. Most radiologists make the diagnosis of vertebral fracture on the basis of a qualitative impression. In contrast, those who conduct research typically make that diagnosis on the basis of a semiquantitative assessment or a quantitative measurement of vertebral dimensions (e.g., vertebral morphometry).

Radiologists qualitatively analyze radiographs of the thoracolumbar spine to identify vertebral fractures in patients whose clinical indications suggest trauma, osteoporosis, malignancy, or acute back pain. While diagnosing the vertebral fracture in question, the observer also considers the potential differential diagnoses of this deformity. The radiologist's decision can be aided by additional radiographic projections (i.e., oblique views) or by complementary examinations (i.e., bone scintigraphy, CT, or MRI).

In a research setting, many different approaches have been used to diagnose and characterize vertebral fractures. The most widely used have been those initially described by Fletcher [51], Barnett and Nordin [52], Hurxthal [53], Smith et al. [54], Minne et al. [55], Melton et al. [56], Black et al. [57], Eastell et al. [58], McCloskey et al. [59], and Genant et al. [60]. Typically, the approaches involve quantitative assessment of vertebral dimensions. Unfortunately, little standardization exists in both the quantitative and qualitative approaches to vertebral fracture diagnosis. This may, in part, explain why a substantial proportion of vertebral fractures remains undetected.

Underdiagnosis of Vertebral Fractures
Vertebral fractures often go undetected by clinicians and undiagnosed by radiologists [17–20]. According to data from the National Ambulatory Medical Care Survey from 1993 to 1997, primary care physicians diagnosed vertebral fracture (or osteoporosis) in 2–13% of white women age 60 years and older, whereas the estimated prevalence in this age group was 20–30% [17–18]. A recent retrospective study of 934 women 60 years old and older found radiographic evidence for 132 moderate or severe vertebral fractures (14%) and showed that only 50% of contemporaneous radiology reports mentioned these fractures [19]. A multinational study [20] of 2,000 postmenopausal women with osteoporosis was conducted, in part, to assess the accuracy of radiographic diagnosis of vertebral fractures by comparing results of local radiographic reports with those of subsequent central readings. This study [20] reported false-negative rates from 27% to 45%, despite a strict radiographic protocol that minimized underdiagnosis due to inadequate film quality. The investigators concluded that the failure to diagnose vertebral fracture is a worldwide problem due in part to the lack of fracture recognition by radiologists and the use of ambiguous terminology in radiology reports.

It would seem that the detection of vertebral fractures should pose no great difficulty. Why then, are so many vertebral fractures being missed? One explanation may relate to the lack of standardization in the radiologic interpretation of vertebral fractures, especially when attention is not focused specifically on the issue of fracture. In this setting, radiologists often fail to recognize or mention many mild and some moderate fractures, or they use terminology that is nonspecific and does not adequately alert the referring clinician to the presence of a vertebral fracture. The diagnosis of vertebral fracture is often unsuspected clinically; this oversight makes accurate radiologic diagnosis essential for proper patient management.

Thus, we propose a call to action, in which radiologists begin to use a simple but standardized approach to diagnosis of vertebral fracture.

Call to Action

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
Because of the serious clinical consequences of vertebral fractures, radiologists must make an effort to improve the accuracy of their diagnoses. They must also reduce the variability in terminology when describing vertebral fractures in patients with osteoporosis. The purpose of this section is to provide the basis for accurate radiologic interpretation and standardized reporting.

Accurate Interpretation
When evaluating imaging studies in which the vertebrae are included (i.e., not just spine radiography but also lateral chest radiography), the following questions are important.

Is there a fracture?—Vertebral fracture should be diagnosed when there is loss of height in the anterior, middle, or posterior dimension of the vertebral body that exceeds 20% (Fig. 1). Special effort should be made not to hedge on the diagnosis of vertebral fractures. If the radiologist cannot decide whether a fracture is present, additional views or additional imaging studies should be recommended. A radiologic hedge can adversely affect patient care by preventing a patient who would otherwise benefit from pharmacologic therapy from receiving it.

View larger version (47K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1. —Drawings show diagnosis and grading of vertebral fractures using semiquantitative method [60]. Vertebral fracture is diagnosed when reduction of height in anterior, middle, or posterior dimension of vertebral body exceeds 20%. Approximate degree of height reduction determines assignment of grade to vertebra. Fractures are classified as wedge, biconcave, or crush, depending on whether anterior, middle, or posterior portion of vertebral body is most diminished in height.

In addition to changes in dimension, vertebral fractures are detected on the basis of the presence of endplate deformities, the lack of parallelism of the endplates, and the general altered appearance compared with neighboring vertebrae (Fig. 2A, 2B, 2C). Radiologists should become familiar with pitfalls in the diagnosis of vertebral fractures. For example, poor technique in which the lateral projection is really an oblique projection may lead to the vertebrae appearing fractured (Fig. 3A, 3B). Similar pseudofractures may be seen on lateral projections in patients with scoliosis. Other abnormalities in vertebral shape may mimic a fracture. Examples include cupid's bow (a developmental variant), limbus vertebra (a developmental variant), Schmorl nodes (vertebral osteochondrosis or Scheuermann's disease), and H-shaped vertebrae (sickle cell disease or Gaucher's disease) (Figs. 4A, 4B, 5, 6, 7, 8). Obviously not every deformed vertebra is a vertebral fracture caused by osteoporosis.

View larger version (82K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A. —Pitfalls in diagnosing vertebral fractures. In all examples, note presence of endplate deformities, lack of parallelism of endplates, or altered appearance compared with neighboring vertebrae. Lateral radiograph of lumbar spine shows mild wedge fracture (grade 1) of L3 vertebra.

View larger version (96K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B. —Pitfalls in diagnosing vertebral fractures. In all examples, note presence of endplate deformities, lack of parallelism of endplates, or altered appearance compared with neighboring vertebrae. Lateral radiograph of lumbar spine shows moderate wedge fracture (grade 2) of L3 vertebra and moderate crush fracture (grade 2) of L2 vertebra.

View larger version (90K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2C. —Pitfalls in diagnosing vertebral fractures. In all examples, note presence of endplate deformities, lack of parallelism of endplates, or altered appearance compared with neighboring vertebrae. Lateral radiograph of thoracic spine shows severe wedge fracture (grade 3) of T7 vertebra.

View larger version (89K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A. —Pitfalls in diagnosing vertebral fractures. Oblique radiograph of thoracic spine shows apparent wedge fracture.

View larger version (86K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B. —Pitfalls in diagnosing vertebral fractures. Lateral radiograph shows normal vertebral shape.

View larger version (89K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4A. —Abnormalities in vertebral shape mimicking fracture. Lateral radiograph of lumbar spine shows deformity of inferior endplates that may mimic vertebral fracture.

View larger version (84K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4B. —Abnormalities in vertebral shape mimicking fracture. Frontal radiograph in same individual shows cupid's bow deformity, a developmental variant.

View larger version (104K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5. —Abnormalities in vertebral shape mimicking fracture. Lateral radiograph of lumbar spine shows limbus L4 vertebra, a developmental variant.

View larger version (100K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6. —Abnormalities in vertebral shape mimicking fracture. Lateral radiograph of thoracic spine shows H-shaped vertebrae in patient with sickle cell disease.

View larger version (98K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7. —Abnormalities in vertebral shape mimicking fracture. Lateral radiograph of lumbar spine shows Schmorl nodes at inferior endplates of L2 and L3 vertebrae.

View larger version (100K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8. —Abnormalities in vertebral shape mimicking fracture. Lateral radiograph of thoracic spine shows endplate irregularity and vertebral wedging characteristic of Scheuermann's disease.

What is the age of the fracture?—This question is particularly relevant in deciding whether a patient's current symptoms are due to that fracture. Unfortunately, on conventional radiographs, it is often difficult to determine the age of the fracture unless prior radiographs are available. When there is cortical disruption or impaction of the trabeculae, the diagnosis of acute fracture is obvious (Fig. 9A). When cortical disruption is not seen and the vertebra appears similar in density to the adjacent vertebrae, the diagnosis of an old fracture is equally apparent (Fig. 9B). However, in many instances, neither criterion is met and additional imaging studies may be useful. Lack of edema on MRI (Fig. 10A, 10B) or lack of radiopharmaceutical uptake on a bone scan (Fig. 11A, 11B) indicates an old fracture. However, even with advanced imaging, it may be difficult to accurately determine the age of a vertebral fracture (Fig. 12A, 12B). Note that even old vertebral fractures are important to mention because they increase the risk of subsequent fractures.

View larger version (132K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9A. —Differentiating acute and old fractures. Lateral radiograph of lumbar spine shows acute vertebral fracture. Note impaction of trabeculae.

View larger version (138K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9B. —Differentiating acute and old fractures. Lateral radiograph of lumbar spine shows old vertebral fracture. Note that fractured vertebra appears similar in density to adjacent nonfractured vertebra.

View larger version (119K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10A. —Lack of edema on MR images indicating old fracture. A Sagittal T1-weighted (A) and T2-weighted fat-suppressed (B) MR images show old L1, L2, and L3 vertebral wedge fractures. Note isointensity of fractured vertebrae compared with nonfractured L4 vertebra.

View larger version (129K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10B. —Lack of edema on MR images indicating old fracture. B Sagittal T1-weighted (A) and T2-weighted fat-suppressed (B) MR images show old L1, L2, and L3 vertebral wedge fractures. Note isointensity of fractured vertebrae compared with nonfractured L4 vertebra.

View larger version (125K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11A. —Lack of radiopharmaceutical uptake on bone scan idicating old fracture. Radionuclide bone scan shows no increase in uptake in lumbar spine.

View larger version (80K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11B. —Lack of radiopharmaceutical uptake on bone scan idicating old fracture. Lateral radiograph shows old mild biconcave fracture of L2.

View larger version (121K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12A. —Bone scanning for determining age of fracture. Radionuclide bone scan shows uptake in L2 vertebra that may indicate acute or subacute fracture.

View larger version (113K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12B. —Bone scanning for determining age of fracture. Lateral radiograph shows severe crush fracture of L2.

Can it be a pathologic fracture?—Critical to the evaluation of vertebral fractures on imaging studies is the fact that not all vertebral fractures are due to osteoporosis. In particular, antecedent trauma, infection, and tumor must be excluded. In many cases, MRI is useful for differentiating osteoporotic fractures from pathologic fractures by showing contrast enhancement of bone marrow and adjacent soft tissues in pathologic fractures. However, early after fracture, enhancement may be seen even in the absence of tumor (Fig. 13A, 13B).

View larger version (88K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 13A. —MRI for determining age of fracture. MR images show acute wedge fractures of T12 and L1 and old wedge fracture of L2. T1-weighted image shows that acutely fractured T12 and L1 vertebrae have lower signal intensity than chronically fractured L2 vertebra.

View larger version (102K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 13B. —MRI for determining age of fracture. MR images show acute wedge fractures of T12 and L1 and old wedge fracture of L2. T1-weighted fat-suppressed image obtained after administration of contrast agent shows enhancement in T12 and L1 vertebrae but no enhancement of L2 vertebra.

Standardized Reporting
After the fracture is detected (and traumatic and pathologic fractures have been excluded), it should be classified as wedge, biconcave, or crush (Figs. 1 and 2A, 2B, 2C). All visualized thoracic and lumbar vertebrae that are fractured should then be graded on the basis of the percentage of reduction in anterior height, middle height, or posterior height (Figs. 1 and 2A, 2B, 2C). This approach to reporting vertebral fracture assessment is based on one that has been widely used in clinical research, the semiquantitative method of Genant et al. [60].

Rationale for Adapting the Genant Method to Clinical Practice

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
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.

Assessment of Fractures on DXA Images

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
Lateral spine images obtained with fan-beam dual-energy X-ray absorptiometry (DXA) systems (Fig. 14A, 14B) offer a potential alternative to radiographs for vertebral fracture diagnosis because vertebral fracture status is frequently unknown at the time of patient evaluation with bone densitometry.

View larger version (85K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 14A. —Alternative to radiography for diagnosing vertebral fractures. Lateral dual-energy X-ray absorptiometry image shows mild thoracic wedge fracture.

View larger version (97K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 14B. —Alternative to radiography for diagnosing vertebral fractures. Lateral radiograph of thoracic spine confirms fracture seen in A.

Several clinical studies have shown the feasibility of visual evaluation of lateral DXA spine images [67–70]. A study of 161 postmenopausal women who had lateral radiographs assessed using the Genant method reported that the DXA images permitted visual assessment of 95% of all vertebrae [70]. Among the vertebrae that could be visualized, there was 92% sensitivity and 96% specificity for detection of moderate-to-severe fractures. A strong overall agreement was found between visual evaluation of DXA images and radiographic results.

The same standardized approach to reporting vertebral fractures described previously should be applied to lateral DXA images. However, some degree of caution is warranted when using lateral DXA images for assessment of vertebral fractures for the following reasons: Many fractures seen on DXA should be confirmed with standard radiographs to exclude the possibility of a pathologic fracture, and patients with indeterminate DXA images (common in the upper thoracic spine) should be referred for radiography.

Conclusion

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 
Despite the difficulties inherent in the assessment of vertebral fractures, their diagnosis is essential for appropriate clinical management. Having a vertebral fracture is a strong risk factor for subsequent fractures, both at new vertebral sites, at the proximal femur, and at other sites susceptible to osteoporosis. As many as two thirds of vertebral fractures do not manifest as acute painful events; therefore, careful scrutiny of all pertinent imaging studies (including lateral chest radiography and DXA) for the presence of vertebral fracture should be encouraged. Using a standardized approach to reporting of vertebral fractures should lead to better communication with clinicians and thus improve the care of patients with osteoporosis.

References

Top Introduction Frequency of Vertebral Fractures Clinical Consequences of... Treatment of Patients with... Diagnosis of Vertebral Fracture Call to Action Rationale for Adapting the... Assessment of Fractures on... Conclusion References

 

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