Vertebral Fracture Assessment on DXA

Understanding Vertebral Fracture Assessment on DXA

Vertebral Fracture Assessment (VFA) is a specialized application of DXA scanning that detects compression fractures of the spine. These fractures are often silent—causing no symptoms—but provide crucial information about bone health and fracture risk.

Unlike traditional spine X-rays, VFA uses the same DXA machine that measures bone density, adding vertebral fracture detection without additional radiation exposure or significant time. This valuable tool can change management by identifying fractures that warrant osteoporosis treatment.

What Is Vertebral Fracture Assessment?

VFA is a low-dose imaging technique that visualizes the thoracic and lumbar vertebrae to detect compression fractures. It's performed at the same time as bone density measurement, providing a comprehensive assessment of bone health.

Types of Vertebral Fractures

Wedge fracture (most common):

• Anterior aspect of vertebra compressed
• Middle and posterior aspects preserved
• Creates wedged appearance
• Common in thoracic spine

Biconcave fracture:

• Central portion compressed
• Endplates concave
• "Fish mouth" appearance
• Creates loss of central height

Crush fracture:

• Entire vertebra compressed
• Uniform height loss
• Most severe type
• Often multiple vertebrae affected

Grading Vertebral Fractures

Fractures are graded by percentage height loss:

Mild (Grade 1):

• 20-25% height loss
• May be difficult to detect
• Still clinically significant

Moderate (Grade 2):

• 25-40% height loss
• Clearly visible on VFA
• Definite fracture present

Severe (Grade 3):

• ＞ 40% height loss
• Easily recognizable
• Significant deformity

Epidemiology and Risk Factors

Vertebral fractures represent the most common complication of osteoporosis:

Age and sex distribution:

• Women: 2x more likely than men
• Prevalence increases with age: 5% at 50-55, 25% at 70+, 40%+ at 80+
• Silent epidemic: Up to 70% are undiagnosed until detected incidentally

Major risk factors:

• Age: Risk increases dramatically after age 65
• Sex: Women, especially postmenopausal
• Low bone density: Osteopenia or osteoporosis on DXA
• Prior fracture: Having one fracture dramatically increases risk of another
• Family history: Parent with hip fracture or kyphosis
• Medications: Long-term corticosteroids, proton pump inhibitors
• Medical conditions: Rheumatoid arthritis, hyperthyroidism, diabetes
• Lifestyle: Smoking, excessive alcohol, sedentary lifestyle

DXA VFA Procedure and Findings

How VFA Is Performed

VFA adds only a few minutes to a standard DXA examination:

The VFA procedure:

1. Positioning: Patient lies supine on DXA table
2. Lateral imaging: Scanner moves laterally to capture spine image
3. Coverage: Typically T4 to L4 vertebrae visualized
4. Duration: Adds approximately 5-10 minutes to standard DXA
5. Radiation: Minimal additional exposure to the spine
6. Analysis: Computer-assisted measurement of vertebral heights

Advantages over standard spine X-rays:

• Lower radiation dose
• Performed at same time as bone density measurement
• Quantitative height measurements
• No additional appointment needed
• Lower cost than radiography

What VFA Detects

Primary fracture signs:

• Anterior wedging: Reduced anterior vertebral height compared to posterior
• Central compression: Reduced middle height compared to ends
• Endplate deformity: Irregular or compressed endplates
• Overall height loss: Reduced total vertebral height

Secondary signs:

• Kyphosis: Increased thoracic curvature
• Reduced disk space: May appear narrowed adjacent to fracture
• Sclerosis: Increased density at fracture site (healing response)

Comparing Normal and Fractured Vertebrae

Clinical Presentation and Detection

When to Consider VFA

Indications for VFA

According to the International Society for Clinical Densitometry (ISCD), VFA is indicated when:

Strong indications:

• Height loss ＞ 4 cm (1.5 inches)
• Self-reported but undocumented vertebral fracture
• Historical radiographs suggesting vertebral abnormality
• Glucocorticoid therapy (≥ 3 months)
• Presence of kyphosis or dorsal kyphosis on exam

Possible indications:

• Height loss 2-4 cm
• Chronic back pain (unrelated to disc disease)
• Mild to moderate trauma in patients over 50
• Significant osteopenia on DXA

Symptoms of Vertebral Fractures

Many vertebral fractures are asymptomatic, but when symptoms occur:

• Sudden onset back pain: Often after minor trauma like sneezing or lifting
• Pain location: Mid-back (thoracic) or lower back (lumbar)
• Pain character: Worse with standing, walking; better with lying down
• Height loss: Progressive over time
• Kyphosis: Forward curvature of upper back (dowager's hump)
• Reduced mobility: Difficulty bending or twisting
• Early satiety: Feeling full quickly due to compressed abdomen

Differential Diagnosis

Several conditions can mimic vertebral fractures on imaging:

Diagnostic Performance and Limitations

Accuracy of VFA

VFA limitations:

• Upper thoracic spine: T4-T6 may be poorly visualized due to shoulders or overlying calcified vessels
• Mild fractures: Grade 1 fractures may be missed
• Obesity: Image quality reduced in very obese patients
• Degenerative changes: Severe scoliosis or osteoarthritis may interfere

When additional imaging is needed:

• Indeterminate VFA findings
• Suspicion of malignancy or pathologic fracture
• Need for better visualization of upper thoracic spine
• Pre-surgical planning

Management Based on Findings

Impact on Treatment Decisions

Finding a vertebral fracture significantly changes management:

If vertebral fracture is present:

• Diagnosis changes: Osteoporosis diagnosis can be made even with T-score ＞ -2.5
• Treatment indicated: Pharmacologic therapy generally recommended
• Monitoring: More frequent follow-up needed
• Fall prevention: Critical to prevent additional fractures

If no fracture detected:

• Reassurance: No silent fractures present
• Continue monitoring: Based on bone density and risk factors
• Focus on prevention: Lifestyle measures to maintain bone health

Treatment Options

Prevention Strategies

Preventing Vertebral Fractures

For those with osteopenia/osteoporosis:

• Pharmacologic treatment: When indicated based on bone density and fracture risk
• Calcium and vitamin D: Adequate intake for bone health
• Weight-bearing exercise: Stimulates bone formation
• Spine-strengthening exercises: Core stability and back extension
• Posture awareness: Prevent kyphosis progression
• Fall prevention: Home safety, balance training, vision correction

Lifestyle modifications:

• Smoking cessation: Smoking accelerates bone loss
• Alcohol moderation: Limit to 1-2 drinks daily
• Healthy weight: Avoid being underweight
• Protein intake: Adequate protein for bone and muscle health

Prognosis and Outcomes

Impact of Vertebral Fractures

After a vertebral fracture:

• 5-fold increased risk of additional vertebral fractures
• 2-3 fold increased risk of hip and other fractures
• Increased mortality: Similar to hip fracture risk
• Functional decline: Reduced mobility, independence
• Quality of life: Chronic pain, depression, social isolation

With appropriate treatment:

• Fracture risk reduced by 50-70% with effective therapy
• Height stabilized: Prevention of further loss
• Pain improved: With appropriate management
• Quality of life: Can be maintained with comprehensive care

Frequently Asked Questions

Do vertebral fractures always cause pain?

No, approximately two-thirds of vertebral fractures are asymptomatic ("silent"). This is why VFA screening is so important—these fractures often go undiagnosed until detected incidentally on imaging. However, silent fractures still increase risk of future fractures and indicate the need for osteoporosis treatment.

How is VFA different from a regular spine X-ray?

VFA uses lower radiation than standard X-rays and is performed on the same DXA machine used for bone density measurement. It's done at the same appointment, adding only a few minutes. While VFA is excellent for detecting moderate-severe fractures, standard X-rays may be needed for indeterminate findings or better visualization of the upper thoracic spine.

Does a vertebral fracture mean I have osteoporosis?

The presence of a vertebral fracture establishes a diagnosis of osteoporosis regardless of your bone density (T-score). This is because fractures indicate that the bone is weak enough to fracture. Many people with vertebral fractures have osteopenia rather than osteoporosis on DXA—the fracture itself confirms the diagnosis.

Can vertebral fractures be treated?

While existing fractures cannot be reversed, their consequences can be managed. For acute painful fractures, vertebroplasty or kyphoplasty can provide rapid pain relief. The most important treatment is addressing the underlying bone weakness to prevent additional fractures. With appropriate osteoporosis treatment, fracture risk can be reduced by 50-70%.

Will I become shorter with vertebral fractures?

Height loss is a common consequence of vertebral compression fractures. Each fracture can cause 1-2 cm of height loss. Multiple fractures can lead to significant height loss and the development of kyphosis (dowager's hump). Treatment can prevent further height loss by preventing additional fractures.

References

1. International Society for Clinical Densitometry. ISCD Official Positions on Vertebral Fracture Assessment. 2023.
2. National Osteoporosis Foundation. The Clinician's Guide to Prevention and Treatment of Osteoporosis. 2023.
3. Gehlbach SH, et al. Vertebral Fracture Assessment. Radiographics. 2022.

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Medical Disclaimer: This information is educational only. Always discuss findings with your healthcare provider for personalized medical advice.