Migration of implants: a problem with injectable polyacrylamide gel in aesthetic plastic surgery.

Polyacrylamide gel (PAAG) has been used as a soft tissue filler material for cosmetic purposes in Europe and China since 1997. The various complications of PAAG have been reported. A total of 15 patients who received PAAG injections at other institutions were treated for gel migration in the authors' hospitals. During treatment, the authors found that the injected PAAG had not formed capsules within the muscle and was encapsulated only by thin fibrous tissue in skin and mammary glands. Consequently, the filler material migrated easily because of muscular activity or the influence of gravity, especially when the capsule was broken by incorrect massage or incidental force. It is suggested that PAAG should not be injected into muscular tissue or subcutaneous areas with active movement, such as joints and muscles involved in facial expression with thin skin. After years of gel implantation, the thinned capsule may result in an increasing incidence of this complication. Management and some clinical findings in relation to the complication also are discussed.