Radial head fracture

Radial head fractures are the most common elbow fractures, accounting for approximately 30% of all elbow injuries. They occur from a fall on an outstretched arm — the radial head impacts the capitellum. The Mason classification (I–IV) describes fracture severity from undisplaced to comminuted radial head with associated injuries. Associated injuries — including medial collateral ligament tears, posterior interosseous nerve injury, and Essex-Lopresti interosseous membrane disruption — must be evaluated.

Lateral elbow pain after a fall, with tenderness over the radial head. The "radiocapitellar joint aspiration test" (removal of hemarthrosis provides immediate pain relief and enables range-of-motion assessment) helps determine if a block to motion exists. AP and lateral X-rays with radiocapitellar view. CT characterizes comminution.

Mason Type II–III fractures with mechanical block to forearm rotation, associated ligament instability, or more than 2 mm displacement with significant angulation require operative treatment.

External patient-education references and related OSI pages for additional background:

• Britannica — Bone disease (fractures)
• Britannica — Joint (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language