What is the next step in managing a patient with an acute on chronic stress fracture of L5 (lumbar vertebra 5) diagnosed on radiograph?

Management of Acute on Chronic L5 Stress Fracture

Obtain an MRI without IV contrast immediately to determine the full extent of injury, assess for complications (osteonecrosis, delayed healing, progression to complete fracture), and guide treatment planning. 1

Why MRI is the Next Step

The radiograph has already confirmed the diagnosis, but an acute-on-chronic presentation requires advanced imaging to answer critical management questions that plain films cannot address 1. MRI provides essential prognostic information beyond simple diagnosis, including marrow edema patterns, cortical signal abnormalities, and fracture line characteristics that predict healing time and guide whether conservative versus surgical management is appropriate. 2, 1

Specific Clinical Scenarios Requiring MRI

MRI is particularly indicated in your patient because:

• Acute-on-chronic fractures suggest failure of initial healing, raising concern for complications like delayed union, nonunion, or progression to complete fracture 1
• Persistent or worsening pain despite appropriate conservative management warrants re-evaluation with MRI 1
• MRI identifies complications such as osteonecrosis or delayed healing that would fundamentally alter management from conservative to surgical 1
• If the patient has osteoporosis or is on bisphosphonate therapy, MRI is critical as these patients are especially prone to progression from incomplete to complete fractures 1
• MRI evaluates the full extent of vertebral involvement, which is essential for surgical planning if conservative management has already failed 1

Alternative Imaging: CT Scanning

CT without IV contrast can be considered only if MRI is contraindicated or unavailable, but it is inferior to MRI for stress fracture evaluation 1. CT may be useful to:

• Identify possible etiologies in delayed healing, such as osteoid osteoma or suspected completion of fracture 1
• Serve as an adjunctive role when other imaging modalities are equivocal 2
• Note: CT with contrast provides no added benefit over noncontrast imaging for stress fracture evaluation 1

Clinical Management Framework

After MRI characterization:

• Most stress fractures respond to conservative management with clinical follow-up until pain-free, followed by controlled activity increase 2, 1
• However, the acute-on-chronic nature suggests initial conservative therapy may have failed, warranting careful MRI assessment before continuing non-operative treatment 1
• Failure of conservative therapy after MRI re-evaluation warrants consideration of surgical intervention, particularly if MRI shows high-grade injury patterns or complications 1

Critical Pitfalls to Avoid

• Do not assume all stress fractures can be managed identically—vertebral location and the acute-on-chronic pattern significantly impact management 1
• Do not delay advanced imaging when symptoms persist or worsen, as this may indicate progression or complications requiring surgical intervention 1
• Do not order CT with contrast, as it provides no additional information for stress fracture evaluation 1
• Do not rely on clinical follow-up alone without MRI in an acute-on-chronic presentation, as this represents a potential treatment failure requiring objective reassessment 1