It all depends on how long ago you had the procedure. Your wound slowly accumulates its previous strength but it will never be as strong as it was. The max strength that you get compared to native untouched skin or tissue is 89%. This is based on studies that test wound strength through tension experiments that test at what point a wound was likely to come a part.

After your procedure, you will gain 60% at 6 weeks, 80% at 6 months, and 88-89% at 2 years.  So, it takes a while to regain most of the strength back. This is important to know when you start exercising after your procedure.

Contact sports is okay especially if you wear head gear. There is no exact answer to which contact sport is or is no okay. The more trauma the worst the damage that you can create to your ears. Otoplasty is dependent most of the time from sutures earlier on and then later scarring that holds the ear in place. Trauma early on based on the above information and previous studies is worse than if it happens later.