All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
The ruling on cosmetic surgery differs according to the purpose of the procedure; whether it is done for beautification purposes or to correct physical deformities (corrective surgery). We have clarified that in several Fataawa, and we ask you to review Fatwa 87848.
You certainly know your own situation better than anyone else and you can decide whether this defect is obvious and embarrassing, causing you emotional distress, or not. If the defect is very embarrassing, causing you considerable emotional distress, then there is no harm - Allaah Willing - in undergoing the cosmetic surgery. However, if this defect does not cause embarrassment and considerable emotional distress, then it is impermissible for you to undergo that surgery because it constitutes changing the creation of Allaah.
If the surgery is permissible for you and an implant is placed under the skin, then it does not affect the validity of Wudhoo' because what is required is that water reaches the skin and this would be achieved.
Allaah Knows best.