Traction apophysitis at the base of the 5th metatarsal (MT). Also known as Iselin’s disease.
Do not confuse this with a base of the 5th MT fracture. These are typically horizontally oriented whereas the 5th MT apophysis is almost vertically oriented. Another important differentiator between Iselin disease and 5th MT fractures is time course. Although patients may report acute worsening of symptoms or feel that the symptoms began when they ‘landed wrong,’ a more detailed history may elicit similar previous pain, indicating a more subacute process.
Read more on ALiEM about 5th metatarsal fractures