What procedure would best address loose left platysma? (Photo)

I would consider thermi as a permanent solution or botox for something less permanent but much less non invasive.  Best, Dr. Emer.

To start, I recommend a proper exam and a review of the operative note to determine the degree of excess skin versus a true platysma separation following your face and neck lift. What you are suggesting is logical although pre-op photos, post op photos taken at 3, 6 and 12 months and a complete exam would provide a much clearer understanding of the problem as well as the best approach (submental vs. ear incision- skin excision vs. platysma tightening) to improve the left neck appearance.   In my opinion trying to answer your question based on 2 photos taken a one point in time 13 months after surgery is very challenging. It is usually best to first discuss with the operating plastic surgeon if you feel comfortable.  Otherwise, I recommend you find a well regarded board certified plastic surgeon in your area to discuss and review. 

Hi Chessmom, from the pictures you have provided, you appear to have some recurrent banding. This would need to be fixed by doing a revision platysmaplasty. It could likely be fixed through a single incision under the chin. The muscle could then be isolated, divided, and re-sutured in order to tighten it and restore contour.