My under the muscle saline implants are 20 years old. Now having pain. What could be causing this long term soreness and ache?

Thanks for your question. It's possible that with compression on your back, the scar tissue around your implants has become stretched or torn to create the discomfort that your experiencing. This is otherwise known as a closed capsultomy, and is not intentionally performed nowadays. Capsular contracture may also be to blame. Implant rupture is a possibility, with subsequent implant deflation and tethering on the implant capsule. It may be time to consider removal with or without replacement. An in person eval will always help to clarify. All my best.

Hi sunny.Your pain/discomfort may be due to muscle strain, stretch of the implant capsule, or a newly developing capsular contracture.  Nonsteroidals like Advil may help if you can tolerate them.  I would visit with your doctor to see if he has anything else to add.  I would also ease off of the exercises to let the muscles heal.sek

Without examining you, it's difficult to diagnose why you are having pain.  However, from what you describe, it's possible that the pressing on your back and compressing the implants caused some small tears in the scar tissue capsules that surround the implants.  Any damaged body part will develop inflammation while it heals and that causes pain.  For now, NSAIDS such as Advil (Ibuprofen) may relieve your symptoms.  See you plastic surgeon if the symptoms persist more than a week or two.  

Also seek in person boarded PS examination of your breasts. If after the examination no findings than logic dictates the chiropractic changes initiated you issues..I do believe exchanging to newer implants is a necessity...

Your situation is not at all unusual. I often see under-muscle patients whose pain is immediately relieved, when they awaken from anesthesia, after moving the implants from under to over. 

Most likely the implant capsule around your implant was torn or severely stretched during the forceful compression of your chiropractic adjustment. If pain continues seek an exam by a board certified plastic surgeon.