What Causes Detachment For Testicle From Spermatic Cord?

the pediatrician said that my 18 month old grandson, while healthy, appears to have one of his testicles detached from the spermatic cord. (What he actually said is one of his balls seems to swing within the scrotum . He said it needed to simply be watched and rechecked when the boy is 2 years old. What is this condition? What are its implications? Thanks