Do you have to wear a cast after an ankle arthroscopy?

Depends: If you are having a procedures that involves fixation of bone, then most likely yes. If it is just to scope out your ankle, then most likely no. A compression bandage is usually applied to minimize swelling.

Generally no: Ankle scopes requires two small 1cm portal incisions where cameras are used to evaluate the anke joint then to clean out synovitic tissue, loose bodies, or repair focal areas of cartilage damage. This would generally require a short boot or splint. If you had a scope assisted ankle fusion or or boney/structural procedure needing post op stability then a cast may be necessary.