Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
If you mean by weaves implanting the hair then there is no harm according to Islamic jurisprudence in hair implantation. This is not considered to be attaching artificial hair with natural hair as mentioned in the Hadith reported by Bukhari and Muslim, the text of which “Allah has Cursed the Wassilah (the woman who makes hair pieces and attaches them to other women’s hair) and Mustawsillah (the woman who has her hair lengthened by artificial hair)”.
Implanting the hair is not considered to be changing the Creation of Allah, because it is bringing back what Allah, The Most-High, has created in the beginning. It is a method of curing, which is permissible as it is an appropriate implantation.
The evidence about this could be found in what was reported by Abu Dawud, and narrated by Abdul Rahman bin Tarfa that his grandfather Arfaja bin Sa’d had his nose cut on the day of Kulab (a battle which took place at the time of Jahiliya), so he took a nose made of silver and attached it instead of his cutoff nose. But "The Prophet (Sallallahu Alaihi wa Sallam) ordered him to take a golden nose instead".
However, wearing wigs is permissible for a completely bald person since it is not considered as an act of attaching hair to the original hair which is forbidden.
Allah knows best.