The sesamoids are two tiny bones underneath the joint of the big toe. An X-ray may show a space within the sesamoid bone. If the line looks jagged, it is probably a fracture.
In some cases, the line is smooth. This suggests a condition called bipartite sesamoid. About 10% of people have this condition. When people have a bipartite sesamoid on one toe, there’s a 25% chance that they’ll also have one on the other toe. If a doctor suspects a bipartite sesamoid, he or she may check the other toe to try and confirm the diagnosis. It would be unlikely to have a sesamoid fracture in both toes, so another line on the second X-ray would definitely suggest a bipartite sesamoid.
If the diagnosis still isn’t clear, the doctor may order a bone scan. A bone scan involves injecting a radioactive chemical, called a “tracer,” into your blood. When the tracer is circulating in your bloodstream, a technician takes pictures using special imaging equipment that detects the radiation. Accumulations of the tracer show up in fractures.