Humeral Shaft Fracture

A humeral shaft fracture is a break in the long middle section of your upper arm bone. They happen from direct blows, falls, or sudden twisting forces. The clinically important feature: the radial nerve wraps closely around the humerus in a groove on the back side. About 10 to 15 percent of these fractures stretch or pinch the nerve, which causes wrist and finger drop (you can't lift your wrist or fingers up). Almost all of these nerve injuries are temporary and recover on their own over weeks to months as the fracture heals. Most humeral shaft fractures themselves heal successfully in a functional brace, without surgery.

You'll know something is wrong immediately — sudden severe pain in the middle of your upper arm, swelling that comes on fast, and often a visible bend or deformity in the arm. Moving the arm or rotating it reproduces a deep grinding sensation. Bruising typically tracks down the inner arm toward the elbow over the first day or two as blood settles with gravity.

The key symptom to report: if you can't lift your wrist or straighten your fingers (called wrist drop), the radial nerve has been stretched or pinched where it wraps around the back of the bone. This happens in roughly 10 to 15 percent of humeral shaft fractures and is almost always temporary — the nerve recovers on its own as the fracture heals — but your surgeon needs to know about it right away so it can be tracked.

Upper arm pain, swelling, often a visible deformity, and grinding when the bone ends move. A careful nerve exam is essential — your surgeon will specifically check that you can lift your wrist and fingers, spread your fingers, and feel sensation in all areas of the hand. Front and side X-rays of the humerus confirm the fracture. A CT scan is added when the fracture is around an existing implant or when the bone looks abnormal (suggesting an underlying tumor or weakness).

Surgery is needed when there's osteomyelitis (bone infection), an open fracture (bone broke through skin), an injury to the artery, a floating elbow (humerus fractured at the same time as a forearm bone), the bone won't stay aligned in a brace, or the fracture is around an existing implant.

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

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