My left leg has been really thinner than my right from birth, Can I get calf implant done on my left leg only?

Hi, 
You are a perfect candidate for custom made implants. These are built using 3D CT scan technology to design and manufacture implants to give you the desired shape. You can have implants on the left side only, to match the right, or on both sides (bigger on the left) to enlarge both. 
Alternatively you can have implants or fat transfers. 
Choose a certified plastic surgeon who is familiar with all these techniques. 

Other than favorable genetics combined with rigorous consistent exercise, there is no other way to augment or restore (in the cases of genetic or aquired disease/trauma) the calf muscles besides calf implants. I do not recommend fat transfer to the calfs for several reasons: 1) it is highly unlikely that the fat will survive in this area, 2) the dying fat may get infected and likely infect the implant as well, 3) whatever fat does survive may be lumpy-bumpy and uneven with the opposite side. Bottom line, fat transfer will NOT work, period! About the same can be said about “fillers” with the addition that they have a high potential for migration when injected in large volumes such as this.
Please know that an extremely few number of board certt plastic surgeons specialize in calf implants so make sure you seek consultation with one that is indeed a reputable and experienced specialist. Glad to be of help.

One of the common uses for calf implants is in the treatment of lower leg asymmetry. Thus you could have only the smaller calf treated with an implant.