2 years post-op. Left breast has doubled in size. Can a torn chest muscle cause swelling over an implant?

Thanks for your question! Couple notes: Usually a pulled muscle wont induce swelling of that size, and had you pulled a muscle you'd have fairly acute pain to incite swelling of that degree. I would recommend seeing your PCP and requesting imaging and/or returning to your surgeon. As a side note to consider, these symptoms are approximately how BIA-ALCL presented in a patient that came to me to have her textured implants removed. Rare, but not unheard of. Best of luck! 

This extent of swelling 2 years after surgery needs to be assessed by your surgeon in conjunction with an ultrasound scan as a minimum.It would be unlikely for a muscle tear to cause this degree of swelling, other causes need to be investigated.Good luck with your treatment.