What is the recommended course of action for a patient with normal x-ray findings of the ankles and feet?

Management of Normal Ankle and Foot X-rays

For patients with normal bilateral ankle and foot radiographs, the recommended course of action depends entirely on the clinical presentation: if the patient is asymptomatic or has resolved symptoms, no further imaging or intervention is needed; however, if pain or clinical concern persists despite normal x-rays, proceed directly to MRI without contrast to detect occult fractures, soft tissue injuries, or early osteomyelitis that are not visible on plain films. 1, 2, 3

Clinical Decision Algorithm

If Patient is Asymptomatic or Symptoms Have Resolved:

• No further imaging is warranted - normal radiographs in the absence of clinical findings require no additional workup 1, 3
• Discharge the patient with return precautions to seek care if new symptoms develop 1
• This approach avoids unnecessary radiation exposure and healthcare costs while maintaining patient safety 1, 3

If Patient Has Persistent Pain Despite Normal X-rays:

For suspected occult fracture or bone stress injury:

• Order MRI of the ankle/foot without IV contrast as the next imaging study - this is the most sensitive modality for detecting occult fractures and bone marrow edema patterns before they become visible on plain radiographs 1, 3
• MRI can detect acute fractures 10-14 days before radiographic changes appear 2
• CT without IV contrast is an alternative if MRI is contraindicated or unavailable, though it is less sensitive for bone marrow edema 1, 3

For suspected osteomyelitis (particularly in diabetic patients or those with foot ulcers):

• Proceed directly to MRI without IV contrast - plain radiographs may remain normal for 10-14 days after infection onset, and negative initial films do not exclude the diagnosis 1, 2
• Consider the probe-to-bone (PTB) test if a foot ulcer is present - a positive test (feeling hard, gritty bone with a sterile blunt probe) has 87% sensitivity and 83% specificity for osteomyelitis 1
• Check inflammatory markers (ESR and CRP) - ESR >60 mm/hr plus CRP ≥80 mg/L has high positive predictive value for osteomyelitis when combined with other findings 1
• Do not delay MRI while waiting for repeat plain films in 2-3 weeks if clinical suspicion is high 1, 2

For suspected tendon pathology:

• Order either MRI ankle without IV contrast OR ultrasound of the ankle - both are appropriate for evaluating tendon abnormalities 1
• Ultrasound has the advantage of dynamic evaluation during specific movements and higher resolution for superficial structures 1
• MRI provides more comprehensive evaluation of all anatomic structures including deep tendons 1

For suspected ankle instability:

• Order either MRI ankle without IV contrast OR MR arthrography of the ankle - both are appropriate for evaluating ligamentous injuries 1
• MR arthrography may provide superior visualization of intra-articular structures 1

For suspected ankle impingement syndrome:

• Order MRI ankle without IV contrast - this is the preferred next study for detecting soft tissue impingement 1

For pain of uncertain etiology:

• Order MRI ankle without IV contrast - this provides global evaluation of all anatomic structures including bone marrow, tendons, ligaments, and soft tissues 1
• Consider ultrasound-guided diagnostic nerve blocks if peripheral nerve pathology is suspected 1

Critical Pitfalls to Avoid

Do not assume normal x-rays exclude significant pathology in high-risk patients:

• In diabetic patients or those with peripheral neuropathy, fractures may be present despite minimal pain or retained ability to walk 3
• Avulsion fractures appear as small bone fragments and are missed on routine radiographs in 40-50% of cases 3
• Early osteomyelitis is not visible on plain films for 10-14 days after infection onset 1, 2

Do not order repeat plain films as the next step when clinical suspicion remains high:

• If osteomyelitis is suspected, proceed directly to MRI rather than waiting 2-3 weeks for repeat radiographs 1, 2
• MRI is far more sensitive than delayed plain films for detecting early bone infection 1, 2

Do not rely solely on imaging in diabetic patients with foot ulcers:

• Combine clinical examination (probe-to-bone test), inflammatory markers (ESR, CRP), and imaging findings to diagnose osteomyelitis 1
• No single test can definitively diagnose or exclude osteomyelitis on its own 1

Do not confuse Charcot neuro-osteoarthropathy with osteomyelitis:

• Both conditions can present with similar radiographic findings in diabetic patients 1, 2, 3
• Bilateral comparison films are essential for differentiation 2, 3
• Initiate immediate knee-high immobilization/offloading for suspected Charcot foot even while awaiting confirmatory advanced imaging 3

Do not skip weight-bearing views when they were not initially obtained:

• Weight-bearing radiographs detect dynamic abnormalities and structural changes not apparent on non-weight-bearing images 2, 3, 4
• If the original films were non-weight-bearing and clinical concern persists, consider obtaining weight-bearing views before proceeding to advanced imaging 3, 4