When surgery has been performed to help reposition ears that protrude to far (otoplasty), there needs to be adequate healing time before one subjects those ears to additional trauma such as contact sports. Healing proceeds in everyone for many months, and typically by 4-5 months collagen (scar tissue) is reasonably strong. But some sports are more risky than others and it would be wise to avoid injuring any facial feature (nose, mouth, eyes, ears, etc) if possible. Volleyball would usually be less risky than soccer which is less risky than boxing. Blows to the ear which are commonly seen in boxing, wrestling and MMA, can permanently injure cartilage of the ear, resulting in a buildup of too much scar, known as "cauliflower ear". So weigh the risks versus benefits of activities that are very physical. If the rewards of the contact sports exceed the pain of physical injury, then that person will continue with the sport. If one decides that preservation of one's face is more important, then an alternate sport will be found.