What does an MRI of an adult patient's elbow with no significant past medical history indicate?

What an Elbow MRI Reveals

An elbow MRI provides comprehensive evaluation of soft tissue structures (ligaments, tendons, nerves, muscles) and osteochondral pathology that cannot be adequately assessed on plain radiographs, making it the gold standard for detecting ligamentous injuries, tendon tears, nerve entrapment, osteochondral lesions, and intra-articular pathology. 1, 2

Primary Diagnostic Capabilities

Ligamentous Injuries

• Ulnar collateral ligament (UCL) tears are detected with 87.5% concordance between MRI and surgical findings, though interobserver reliability for UCL assessment is notably lower than for lateral collateral complex injuries 1
• Lateral collateral ligament complex injuries show the best interobserver agreement on MRI with 90.9% concordance with surgical exploration 1
• Anterior capsule tears are routinely identified in acute elbow dislocations, along with associated medial and lateral collateral ligamentous injuries 1

Tendon Pathology

• Distal biceps tendon tears are detected with 92.4% sensitivity and 100% specificity for complete ruptures, though sensitivity drops to 59.1% for partial tears 1
• Partial rupture of the long head of the biceps with intact short head represents the most common injury pattern, while isolated complete ruptures of the long head are least common 1
• Triceps tendon tears can be characterized by mechanism: indirect injuries (fall on outstretched hand) typically affect lateral and long heads with intact medial head, while direct injuries more commonly cause full-thickness ruptures 1
• Lateral epicondylitis demonstrates 90-100% sensitivity and 83% specificity with characteristic intermediate to high T2 signal within the common extensor tendon and paratendinous soft tissue edema 1, 2, 3
• Medial epicondylitis shows 90-100% sensitivity on MRI 2, 4

Specialized Imaging Techniques

• FABS (flexion-abduction-supination) view provides an unraveled view of the entire distal biceps tendon on a single image, with better interrater reliability than standard views and significantly more accurate grading of pathology extent compared to surgical findings 1
• This specialized view may benefit challenging cases of high-grade partial versus complete tendon tears by identifying subtle residual tendon fibers 1

Nerve Pathology

• T2-weighted MR neurography serves as the reference standard for ulnar nerve entrapment, demonstrating high signal intensity and nerve enlargement 2, 4

Osteochondral and Intra-articular Pathology

• Osteochondral lesions of the capitellum or medial trochlea are identified on standard sequences 2, 4
• Loose bodies are best detected on T2-weighted images 2
• Occult fractures not visible on radiographs can be identified 2, 4
• Heterotopic ossification and soft tissue calcification within tendons are visualized 2, 4

Important Limitations and Pitfalls

Diagnostic Accuracy Concerns

• MRI may overestimate triceps tear severity compared with surgical assessment 1
• Cartilage abnormality detection is limited, with accuracy of only 45% for the radius, 64% for the capitellum, 18% for the ulna, and 27% for the trochlea 2
• Standard MRI without contrast may be insufficient for complete evaluation of collateral ligament injuries—MR arthrography at 3T provides superior accuracy with 81% sensitivity, 91% specificity, and 88% accuracy for UCL tears 1, 2, 4

Interpretation Challenges

• Normal anatomic variants may be misinterpreted as pathologic, requiring careful correlation with clinical findings 2, 4
• Pain may be referred from cervical spine pathology or radial tunnel syndrome, necessitating broader diagnostic consideration when MRI findings don't correlate with symptoms 2, 4, 3

Clinical Context for Interpretation

When MRI Changes Management

• Facilitates surgical planning by demonstrating associated findings such as radial collateral and lateral UCL injuries in epicondylalgia 1, 3
• Differentiates partial from complete tears, particularly important for UCL injuries in throwing athletes 1
• Documents injury severity to estimate recovery time and guide treatment decisions 5, 6
• Identifies acute trauma superimposed on chronic tendinopathy or repetitive microtrauma injuries 6

Athletic Injuries

• UCL injuries predominate in overhead throwing athletes and Olympic-level competitors 1
• Traumatic ruptures have significantly higher association with short head biceps tendon involvement, while atraumatic ruptures involve the long head in 89% of cases 1