If budgerigar is lame, consider spraying Yunnan Baiyao spray on the bird's wound, which can help clean, stop bleeding and reduce swelling. However, please be careful not to spray drugs into birds' eyes or mouths.
In addition, the bird's leg can be restored and wrapped with sterile gauze, then wrapped with a straw and fixed with adhesive tape. Change gauze and medicine every two days to promote wound healing.
If budgerigar's legs are splayed, they need to be tied with ropes to correct them.
Please note that the above suggestions are for reference only. If the bird is seriously injured, it is recommended to seek the help of a professional veterinarian as soon as possible.