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Atraumatic osteolysis of the distal clavicle: MR findings
1Department of Radiology, University of Washington School of Medicine, Seattle.
Objective:
The purpose of this study was to describe the MRI appearance in atraumatic osteolysis of the distal clavicle (AODC).
Materials And Methods:
We retrospectively evaluated MRI, medical records, ancillary diagnostic imaging studies and clinical course in five men and two women (mean age, 39 years) in whom the final clinical diagnosis of AODC was established. None of the patients had significant shoulder injury, but all participated in activities involving repetitive strain of the acromioclavicular (AC) joint. In three of these patients, we performed follow-up MRI (ranging from 5 1/2 to 15 months after the initial MRI).
Results:
In all seven patients, signal intensity changes within the intramedullary portion of the distal clavicle on MRI were consistent with diffuse bone marrow edema. Marrow edema was most conspicuous on STIR imaging and occasionally could be misinterpreted as normal marrow signal patterns on spin-echo imaging. Cortical thinning or irregularity of the distal clavicle was seen in six cases and tiny subchondral cysts were seen in three, corresponding to subtle cystic changes on shoulder radiography. Limited bone scans obtained in two patients showed markedly increased uptake of radiotracer at the distal clavicle and AC joint. Histologic examination in one case showed disruption of articular cartilage, subchondral cysts, and metaplastic bone formation with increased osteoclastic activity. Follow-up MRI in three patients who were asymptomatic following conservative therapy showed normalization of marrow signal intensity.
Conclusion:
Atraumatic osteolysis of the distal clavicle is a relatively uncommon but important cause of shoulder pain. Particularly when the clinical history is suggestive of repetitive AC joint stress, MRI of the distal clavicle should be examined closely for marrow edema, cortical irregularity, and cystic changes. Such abnormalities may be especially conspicuous when STIR imaging techniques are used.
Insights
Atraumatic osteolysis of the distal clavicle (AODC) causes shoulder pain. MRI reveals bone marrow edema, cortical irregularity, and cysts, especially with STIR imaging, aiding diagnosis in repetitive AC joint stress cases.
Area of Science:
- Radiology
- Orthopedic Imaging
- Musculoskeletal Radiology
Background:
- Atraumatic osteolysis of the distal clavicle (AODC) is an uncommon cause of shoulder pain.
- Repetitive strain of the acromioclavicular (AC) joint is often implicated in AODC.
- Accurate diagnosis is crucial for effective management of shoulder pain.
Purpose of the Study:
- To characterize the magnetic resonance imaging (MRI) findings in atraumatic osteolysis of the distal clavicle (AODC).
- To correlate MRI findings with clinical presentation and other diagnostic modalities.
- To improve the diagnostic accuracy of AODC using MRI.
Main Methods:
- Retrospective review of MRI, medical records, and ancillary studies in seven patients diagnosed with AODC.
- Analysis of MRI findings including bone marrow edema, cortical changes, and cystic lesions.
- Correlation of imaging findings with clinical history of repetitive AC joint stress and follow-up imaging in three patients.
Main Results:
- All patients exhibited diffuse bone marrow edema in the distal clavicle on MRI, most evident on STIR sequences.
- Cortical thinning or irregularity was present in six patients; subchondral cysts were seen in three.
- Bone scans showed increased radiotracer uptake; histology revealed cartilage disruption and osteoclastic activity.
- Follow-up MRI demonstrated normalization of marrow signal intensity after conservative therapy.
Conclusions:
- MRI is valuable for diagnosing AODC, particularly when STIR sequences highlight marrow edema.
- Key MRI findings include bone marrow edema, cortical irregularity, and cystic changes in the distal clavicle.
- Recognizing these MRI abnormalities is important for patients with shoulder pain and a history of repetitive AC joint stress.