Distal tibiofibular radiological overlap: Does it always exist?

OBJECTIVES: Overlap between the distal tibia and fibula has always been quoted to be positive. If the value is not positive then an injury to the syndesmosis is thought to exist. Our null hypothesis is that it is a normal variant in the adult population. METHODS: We looked at axial CT scans of the ankle in 325 patients for the presence of overlap between the distal tibia and fibula. Where we thought this was possible we reconstructed the images to represent a plain film radiograph which we were able to rotate and view in multiple planes to confirm the assessment. RESULTS: The scans were taken for reasons other than pathology of the ankle. We found there was no overlap in four patients. These patients were then questioned about previous injury, trauma, surgery or pain, in order to exclude underlying pathology. CONCLUSION: We concluded that no overlap between the tibia and fibula may exist in the population, albeit in a very small proportion.