Lower Leg X-Ray: Indications and Management Algorithm
X-ray is the first-line imaging modality for lower leg evaluation in suspected trauma or stress fractures, with specific clinical decision rules guiding when imaging is necessary. 1, 2
When Lower Leg X-Ray is Necessary
Acute Trauma Scenarios
- Apply Ottawa rules to determine imaging necessity in acute lower extremity injuries—these rules are highly sensitive and NICE-recommended, though they should not be used in patients with penetrating trauma, pregnancy, skin wounds, altered sensorium, neurologic abnormalities, or underlying bone disease 2, 3
- Standard radiographic protocol includes three views: anteroposterior, lateral, and mortise views 2, 4
- Weight-bearing radiographs are preferred when possible, particularly for suspected fracture instability, as they detect dynamic abnormalities not apparent on non-weight-bearing images 2
Suspected Stress Fractures
- X-ray is rated 9/9 (usually appropriate) as the first imaging study for suspected stress fractures of the lower extremity excluding pelvis and hip 1
- Initial radiographs may be negative in early stress fractures, but they remain the appropriate starting point due to low cost and radiation exposure 1
Special Populations Requiring X-Ray
- Diabetic patients with neuropathy and suspected fractures should undergo X-ray imaging, as Ottawa rules should not be applied in this population 2
- Suspected Charcot neuro-osteoarthropathy in diabetic patients requires bilateral plain X-rays as initial imaging 2
- Patients on long-term bisphosphonate treatment (3-5 years) with thigh or groin pain should undergo X-ray evaluation 2
Pediatric Considerations (Age <5 Years)
- Limited tibial/fibula radiographs are suggested as initial evaluation in walking children with acute limp, rather than total lower extremity radiographs 1
- Spiral tibial fractures are the most common fractures in children <4 years presenting with nonlocalized limp or refusal to bear weight 1
- Approximately 10% of tibial fractures are only visible on follow-up radiographs, not initial imaging 1
Next Steps in Management
When Initial X-Rays Are Negative
For Suspected Stress Fractures:
- MRI without IV contrast is rated 9/9 (usually appropriate) as the next imaging study when radiographs are negative but clinical suspicion persists 1
- Repeat X-ray in 10-14 days is rated 7/9 (usually appropriate) and represents a less sensitive but reasonable alternative to MRI 1
- CT without contrast (rated 5/9) and bone scan with SPECT (rated 5/9) are "may be appropriate" alternatives when MRI is unavailable 1
For Acute Trauma:
- Follow-up clinical reassessment is necessary if initial evaluation is negative and symptoms persist or worsen 1
- Repeat radiographs or imaging of adjacent areas may be useful, as some fractures become visible only on follow-up imaging 1
Pregnant Patients
- MRI without contrast is the initial imaging test of choice (rated 9/9) for suspected stress fractures in the pelvis 1
- For long bone stress fractures in pregnant patients, radiographs should be initial imaging, with MRI performed as complementary study if radiographs are equivocal or negative 1
- Fetal absorbed dose from lower extremity radiographs is minimal (<1 mGy), and benefit far outweighs risk for diagnostic imaging not involving abdomen or pelvis 1
Critical Pitfalls to Avoid
Timing of Manipulation
- Perform X-rays BEFORE attempting manipulation of deformed ankle injuries in the absence of neurovascular deficit or critical skin compromise 5
- Manipulation before X-ray significantly increases risk of re-manipulation (44% vs 18%, RR=2.72) without improving surgical timing 5
- Only manipulate before imaging if there is documented vascular compromise, nerve symptoms, or critical skin compromise 5
Application of Clinical Decision Rules
- Do not apply Ottawa rules in patients with diabetes and peripheral neuropathy, as sensitivity is reduced in this population 2, 3
- Ottawa rules have limited benefit in patients with altered sensorium or underlying bone disease 2