Can Implants That Have Been Placed over the Muscle Be Replaced Behing the Muscle?

Certainly  implants can be replaced in a different pocket and very commonly done under the muscle in patients with thin soft tissue coverage.

Implants placed behind the muscle have better coverage so they typically show less rippling than sublandular implants.  Also, submuscular position of implants have a lower risk of capsular contracture.  Change of pocket from subglandular to submuscular can be performed but, it has its inherant risks that must be discussed with the patient.