Thank you for your question. Any implant has the possibility to move yet it is relatively rare. If the calf implant was put under the fatty tissue, it is more likely to move. This is why most of us place the implants under the muscle fascia (I have done approximately 120 calf augmentations in Toronto Canada). They cannot easily move as they are bound by the fascia. Rarely however, a capsular contracture can occur (1-3%) and this can shift the implant. In those cases, it is recommended to change the implant. It has to do with the biofilm theory of capsular contracture. See my video on body implants. Hope this helps! Dr. Marc DuPere, Toronto Plastic Surgeon Board-Certified.