what happens if i do not have any further surgery on my knee for my injury?

This of course depends on the injury. But, if we presume that your knee is stable and you have an isolated injury to your joint surface, then you can anticipate several things. If the lesion is very small, less the one centimeter in diameter, you may go for several years without any symptoms. If, however, your injury is larger or in one of the more important weight bearing areas, then, without appropriate treatment, you will have a greater than normal chance of arthritis. In that case, you can anticipate pain, swelling, occasional locking and giving way. These symptoms may well progress in severity with time.