The term "cankle" is not a medical term, diagnosis or medical condition. It most commonly refers to thick ankles. The width of these ankles make it difficult to distinguish the normal anatomy of the muscles, tendons and bones of the lower leg. People come in all shapes and sizes and thick ankles may be due to obesity, pregnancy, conditions causing chronic ankle swelling or may simply be hereditary. Exercise directed at the muscles of the lower leg may help define the muscles and thereby reducing the nondescript appearance.
It is however, important to differentiate ankles with this persistent thickness in anatomy from those that develop the condition suddenly or even gradually. Many systemic conditions can cause gradual swelling of the ankles (examples include kidney disease, venous disease and heart disease) and certainly trauma can cause acute or sudden swelling. A deep vein thrombosis can also cause a swollen lower leg and ankle.
A podiatric physician, also known as a podiatrist, should examine any new swelling or thickness to rule out injury, trauma or damage to the tendons in the leg and ankle. Two very common tendons that would cause thick ankles are the Achilles tendon and the posterior tibialis tendon that supports the ankle and arch. Ankle sprains, both old and new, cause thickness around the outside of the ankle. Swelling of the ankles and lower leg is treated frequently by podiatrists using a soft cast, known as an unna boot.
It is also common for women beyond their forties to develop fatty ankles due to fat deposits around and below the ankle. Often, these deposits put pressure on the nerves and can be problematic.