Distal Biceps Tendon Rupture

The biceps tendon at the elbow anchors your biceps muscle to the forearm bone (the radius). It's the main muscle that turns your palm up — and a secondary contributor to bending your elbow. A complete rupture usually happens to men in their 40s or 50s when the arm gets caught fighting an unexpected sudden force with the elbow bent at 90 degrees. There's a distinct "pop," then pain at the front of the elbow, bruising, and the muscle balls up higher in the arm than it should — the so-called reverse Popeye appearance.

This is different from a biceps tendon rupture at the shoulder (which is mostly cosmetic). Without repair, you lose 30 to 40 percent of your palm-up turning strength permanently. For most active patients, prompt surgical repair is the right call to get full strength back.

The hallmark is a sudden pop at the front of your elbow during a forceful lift — typically when you're catching something heavy with your arm bent at about 90 degrees. Immediate sharp pain follows at the crook of the elbow, then bruising that can track down your forearm over the next day or two. The muscle balls up higher in your arm than normal, creating a visible lump near the shoulder — the so-called reverse Popeye deformity.

You'll notice weakness when you try to turn your palm up (like using a screwdriver or turning a doorknob) and, to a lesser extent, when bending your elbow against resistance. The front of the elbow feels hollow where the tendon used to be, and hooking a finger into the bend of the elbow confirms the gap. Some patients report a dull ache that persists for weeks even though the initial sharp pain fades relatively quickly.

Pain at the front of the elbow and bruising after the injury. Your surgeon will use the hook test — sliding a finger under where the biceps tendon should be at the bend of the elbow. In an intact tendon, the finger hooks under it; in a complete rupture, it doesn't — and that's essentially diagnostic. MRI confirms whether the tear is complete or partial and measures how far the muscle has retracted up the arm.

Early repair — done within the first few weeks before the tendon scars and pulls up the arm — is recommended for most active patients to get full strength back. The longer you wait, the more the tendon retracts and adheres to surrounding tissue, making the eventual repair technically harder and the result less reliable.

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

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