In a patient with a one‑month history of new‑onset thumb interphalangeal joint pain and popping on flexion, no trauma, and a normal plain‑film X‑ray, should I obtain an MRI now?

Thumb IP Joint Pain with Popping: MRI Not Indicated Now

In a patient with one month of thumb interphalangeal joint pain and popping on flexion, with normal radiographs and no trauma, you should NOT order an MRI at this time. The clinical presentation most likely represents a soft-tissue pathology (trigger thumb or stenosing tenosynovitis) that does not require advanced imaging for diagnosis or initial management.

Clinical Reasoning

Why MRI Is Not Appropriate Now

• Normal radiographs exclude fracture and significant bony pathology that would require immediate surgical intervention, such as avulsion fractures involving ≥1/3 of the articular surface or subluxation 1
• The ACR Appropriateness Criteria indicate that MRI is reserved for specific clinical scenarios where radiographs are nondiagnostic AND there is suspicion for occult fracture, stress fracture, or specific soft-tissue pathology that would change management 2
• Your patient has no trauma history, making occult fracture extremely unlikely—the primary indication for MRI after negative radiographs in joint pain 2

What This Clinical Picture Suggests

The combination of popping with flexion + no trauma + normal X-ray strongly suggests:

• Trigger thumb (stenosing tenosynovitis): The popping or clicking sensation during flexion is pathognomonic for tendon catching at the A1 pulley 2
• Ultrasound would be the appropriate advanced imaging if needed, as it can directly visualize the flexor tendon, tendon sheath thickening, and dynamic catching during flexion 2

Appropriate Next Steps

Initial Management Without Advanced Imaging

• Clinical diagnosis is sufficient for trigger thumb—the history of popping/clicking with flexion is diagnostic 2
• Conservative treatment should be initiated first: splinting in extension, NSAIDs (topical preferred over oral for safety), and activity modification 1
• Ultrasound can be considered if diagnosis is uncertain or to guide therapeutic injection of the tendon sheath, as US is validated for guiding soft-tissue injections 2

When MRI Would Be Indicated

MRI without contrast would become appropriate only if:

• Symptoms persist despite 6-8 weeks of conservative management AND there is concern for alternative diagnoses (ligamentous injury, occult ganglion cyst, or inflammatory arthritis) 2
• Clinical suspicion shifts to inflammatory arthritis with systemic symptoms or multiple joint involvement—MRI with contrast can detect synovitis and bone marrow edema that predicts disease progression 2
• Palpable mass develops, suggesting occult ganglion cyst, though ultrasound would still be first-line imaging 2

Common Pitfalls to Avoid

• Do not order MRI reflexively after normal radiographs—this leads to unnecessary cost, patient burden, and potential overtreatment of incidental findings 2
• Do not miss the clinical diagnosis of trigger thumb—the popping sensation is the key clinical feature that makes this a clinical diagnosis, not an imaging diagnosis 2
• Do not delay conservative treatment while waiting for imaging—splinting and NSAIDs should begin immediately based on clinical findings 1
• Remember that MRI findings in asymptomatic individuals are common—bone marrow edema and other "abnormalities" may not represent true pathology requiring treatment 2