I broke my ankle last year and recovered with a cast but i still sprain it a lot. also whenever i play ball without rolling the ankle it swells?

Ligament laxity: You may have developed some ligamentous laxity either as part of the fracture injury or something else. Regardless, it can be associated with instability (not necessarily gross instability) that can recurrebe associated with recurrent swelling, weakness, and or local muscular atrophy.

Cartilage damage: A broken ankle will typically not tear the same ligaments that rolling you ankle will. Ankle sprains can vary a great deal, but is still a discreet and separate injury from the broken ankle. Swelling without a sprain or rolling the ankle often points toward cartilage damage that causes swelling each time the damaged area is irritated and made to bleed. An MRI can often sort this out.

Sprains are common: Once injured, the area is at risk for re-injury. The ligaments in the area usually heal with scar tissue which is not as strong as the original tissue. You may want to wear an ankle support brace when performing sports to provide your ankle greater support and stability.