Thanks for your question and concern; I can understand your worries. I must tell you that if your husband is hit or kicked in the testicles it will not affect in the vasectomy of your husband. Your husband’s vasectomy will be unaffected. He will still remain infertile. There is about even less than 1% failure rate with this procedure. After the procedure the semen should be assessed and prior to other methods of contraception should be stopped which can ensure infertility. But above all this fact I must tell you that you do not have to be concerned. As you told me he had this procedure three years ago therefore, there is no reason that you should be worried on this matter. It has been three years since he had vasectomy and if everything is going smooth and fines you must relax and should not worry on this matter. However, if your husband experiences any problem then there comes a question of being worried but as you told me that it is going smooth and fine then there is no point of being worried unnecessarily. You should enjoy your life without worries and tensions.There is no chances of Knoppix seen in your case. So according to me if everthing is going fine then let it go but for the assurety see a doctor in person and get it consult. Best wishes.