It marked the beginning of the end of Smith's United career - but he hopes Valencia can make a full and speedy recovery.
Smith, 29, told The Sun: "I can relate to what Antonio is going through.
"There's no getting away from the fact it is a hard road back from an injury like that but with determination, you can do it.
"It means weeks of doing virtually nothing then long days with the specialists, the physios and in the gym building your ankle up before you can even think about kicking a ball again.
"But the thought of being able to get back on the field is what keeps you going, no matter how far away that day may seem.
"Valencia is in good hands. United's medical team are excellent and always keep your spirits up.
"He will get so much support from the fans too. They were always sending me messages while I was out and I'm sure it will be the same for Antonio. I really felt for him and it brought back memories of my injury at Anfield.
"It's strange sometimes what causes serious injuries. Mine was caused by blocking a free-kick when there was no one near me.
"I just hope, like everyone in football, that Antonio can work his way through rehab and wish him all the best for a complete recovery."