Radial Head Fracture

The radial head is the disc-shaped top of the smaller of your two forearm bones — the one that rotates when you turn your palm up and down. A radial head fracture is when that disc cracks or shatters, almost always from falling onto an outstretched arm. The shock travels up your forearm and the radial head slams into a corresponding bony bump on the upper-arm bone (the capitellum) and breaks. It's the most common elbow fracture — about 30% of all elbow injuries. Surgeons grade severity on a I-through-IV scale (the Mason classification) from a hairline crack to a shattered radial head with other ligament tears. Your provider also checks for nearby injuries that often happen at the same time — a torn inner-elbow ligament, a stretched nerve, or a more serious injury that splits the fibrous sheet running between the two forearm bones.

• Pain on the outer side of the elbow — sharp pain right over the radial head, starting immediately after a fall on an outstretched hand.
• Swelling and stiffness — the elbow fills with blood (hemarthrosis) within hours, making it feel tight and difficult to bend or straighten.
• Inability to rotate the forearm — turning your palm up (like accepting change) or down (like typing) is painful or blocked.
• Pain with gripping or lifting — any force transmitted through the forearm loads the fractured radial head and hurts.
• A clicking or catching sensation — if a bone fragment has shifted, you may feel something catching as you try to move the elbow.

Pain on the outer side of your elbow after a fall, with tenderness right over the radial head. Sometimes the joint fills with so much blood that it locks up — your provider can drain it with a needle, which both relieves the pain and lets them check whether the bone fragments are blocking the elbow from rotating. Three X-ray views, including a special radial head view, show the fracture. A CT scan adds detail when the bone is shattered into many pieces.

Surgery is needed when a piece of bone blocks the elbow from rotating, when the surrounding ligaments are also torn and the elbow is unstable, or when the fracture is displaced enough (more than about 2 mm with angulation) that it won't heal cleanly on its own. The operation pins the fragments back together, or — if the head is too shattered to rebuild — replaces it with a small metal implant.

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