What imaging study should be ordered for a patient with chronic left shoulder pain worsening over the past three months, with audible crepitus and popping over the clavicle, and a negative X‑ray?

MRI Without Contrast Is the Next Imaging Study

For a patient with chronic shoulder pain, crepitus, and popping localized to the clavicle whose radiographs are negative, order MRI without intravenous contrast to evaluate for distal clavicular pathology, acromioclavicular joint derangement, and associated soft-tissue abnormalities. 1

Clinical Reasoning

Your patient's presentation—chronic pain with audible crepitus and popping specifically over the clavicle—strongly suggests acromioclavicular (AC) joint pathology or distal clavicular abnormality. The negative radiograph does not exclude significant pathology, because early AC joint degeneration, distal clavicular osteolysis, and soft-tissue injuries around the AC joint are often radiographically occult. 2

Why MRI Without Contrast

• MRI is the appropriate next step after negative radiographs for chronic shoulder pain when a specific anatomic pain generator (in this case, the AC joint and distal clavicle) is suspected based on clinical localization. 1, 3

• MRI detects distal clavicular bone marrow edema (increased T2 signal), which occurs in 12.5% of shoulder MRI examinations and can represent early osteolysis or stress reaction of the distal clavicle—a condition that may cause disabling AC joint pain despite normal radiographs. 2

• In patients with chronic AC joint pain and no radiographic abnormality, increased T2 signal in the distal clavicle on MRI may be the only imaging finding and can guide surgical decision-making (distal clavicle resection) when conservative therapy fails. 2

• Intravenous contrast is not required for evaluating bone marrow edema, AC joint degeneration, or associated rotator cuff pathology in the chronic setting. 1, 3

Alternative Imaging Considerations

• Bone scintigraphy (bone scan) has high sensitivity (82%) for AC joint pathology and, when combined with a positive Paxinos test (compression and anterior-to-posterior force across the AC joint), yields a 99% post-test probability of AC joint pain. 4 However, bone scanning is less commonly used in contemporary practice and provides less anatomic detail than MRI. 4

• Ultrasound is excellent for superficial soft-tissue masses and rotator cuff evaluation but has limited utility for assessing intra-articular AC joint pathology and distal clavicular bone marrow changes. 5, 3

• CT is not routinely indicated for initial soft-tissue or AC joint evaluation unless there is a need to characterize complex osseous anatomy or mineralization after radiography. 5

Pitfalls to Avoid

• Do not assume a negative radiograph excludes significant pathology. Early AC joint degeneration, distal clavicular osteolysis, and labral or capsular injuries are frequently radiographically silent. 2, 6

• Do not order MR arthrography in this chronic presentation. MR arthrography is reserved for suspected labral tears or glenohumeral instability, particularly in subacute or chronic settings where joint effusion is absent. 7 Your patient's symptoms localize to the clavicle, not the glenohumeral joint, making arthrography unnecessary. 7

• Recognize that AC joint tenderness has 96% sensitivity but low specificity for AC joint pathology; imaging confirmation is essential before proceeding to invasive treatment. 4

Clinical Algorithm

1. Confirm clinical localization: Palpate for AC joint tenderness and perform the cross-body adduction test and Paxinos test to corroborate AC joint as the pain source. 4, 6

2. Order MRI of the shoulder without contrast to evaluate:

   • Distal clavicular bone marrow signal (increased T2 signal suggests osteolysis or stress reaction) 2
   • AC joint degeneration, capsular thickening, or joint effusion 6
   • Associated rotator cuff pathology (common in older patients) 7, 6

3. If MRI confirms distal clavicular edema or AC joint pathology and conservative therapy (NSAIDs, activity modification, physical therapy) fails, consider referral for distal clavicle resection. 2

4. If MRI is negative or equivocal and clinical suspicion remains high, consider bone scintigraphy as an adjunct, particularly if the Paxinos test is positive. 4