Patients and athletes who complain about consistent discomfort in their anterolateral ankle may have come to develop a sinus tarsi syndrome (STS).
The sinus tarsi is the bony canal that is formed between heel bone (calcaneus) and the bone directly above it (talus). The bony canal is held together by ligaments and sinus tarsi syndrome is the injury of these ligaments.
Two main reasons for developing this syndrome are: from overuse in conjunction with over pronation or poor foot biomechanics or developed as secondary traumatic injury (Helgeson, 2009). The majority of patients have suffered an inversion ankle sprain at some point in the past.
The sinus tarsi has a lot of synovial fluid / tissue which becomes inflamed. It may also occur with inflammatory conditions such as gout or osteoarthritis.
Helgeson K., 2009, Examination and Intervention for Sinus Tarsi Syndrome, North American Journal of Sports Physical Therapy, 4(1); 29-37