Anterior Interosseous Nerve Syndrome occurs when the interosseous nerve—a major nerve located about two inches below the elbow—becomes entrapped or compressed by surrounding muscles, blood vessels, ligaments or scar tissue.

Common symptoms include vague pain in the upper forearm and the inability to pinch the thumb and index finger together (into the “OK” sign).

Conservative treatment includes rest and stretching.

Surgery to release the nerve from entrapment may be necessary in cases that do not respond to rest.