Silva announced his retirement after breaking down in preseason.
He told El Diario Vasco: "The signing was done very quickly. The truth is that I was right to come, because I am loving it in San Sebastián, as well as the three years I was with the team.
"My family is delighted here, the people have always shown us a lot of love, and that is why we decided to do the knee recovery here and stay in San Sebastián. We had everything planned to continue playing for another year and the children's schools were booked."
On his recovery, he added: "It's going very well, really. Right now it is my priority and I don't think about anything else."