Nail plate injuries that also affect the nail matrix can be complicated. The nail plate covers the nail matrix, which is divided into two matrices: germinal and sterile. The nail matrix (also known as matrix unguis) is formed by these two layers of cells at the base of the fingernail (or toenail).
This tissue consists of rapidly dividing skin cells that soon fill with the protein keratin. The matrix of finger nails consists of the most rapidly dividing skin cells in the body. The matrix is involved in growth and position of the nail plate.
A crush injury (however it is caused) compresses the nail matrix between the nail plate and the bone. Damage to the nail bed can lead to the formation of scar tissue and misalignment of matrices and nail plate. However, in the acute phase (immediately after the injury), the more immediate problem is the subungual hematoma. Healing may not occur until and unless that hematoma is removed, which it sounds like you have had this procedure done.
Because injury affects the growing nail plate, growth is slowed considerably. Infection and scar formation can slow nail plate growth even more. During the first three weeks after injury, growth is very stunted. Then for the next six weeks, you should experience a period of very rapid growth and recovery.
Eventually the nail plate is fully restored (usually two to four months after the injury). After that normal growth returns. Complications such as bone fracture (especially if the fracture site is unstable) can further delay recovery.