When a nail sustains a significant injury, the quick answer is that a broken nail does not fuse or “grow back together” like mending bone. The visible part of the nail, the nail plate, is composed of hardened, dead keratin protein. Because this material is non-living tissue, it lacks the biological ability to repair itself once fractured or separated. The only way to resolve a break is for the damaged nail plate to be pushed off and completely replaced by new growth.
The Biology of Nail Growth
New nail cells originate from the nail matrix, a specialized tissue located beneath the skin at the base of the nail. This matrix acts as the growth center, continuously producing new cells responsible for the entire nail plate. The matrix is typically hidden beneath the cuticle, and its health is paramount for normal nail formation.
The cells produced by the matrix harden and flatten into the translucent nail plate as they move forward over the nail bed. The nail bed is the soft, vascularized tissue that lies directly beneath the nail plate and provides support. Damage to this growth center can lead to permanent changes in the shape or texture of the new nail.
The Healing Process After a Break
The recovery process focuses entirely on growing a new, healthy nail to replace the damaged one. New growth begins at the matrix and slowly migrates forward along the nail bed. As the new nail plate advances, it naturally pushes the old, broken portion of the nail off the digit. Complete regrowth is time-consuming.
A fingernail takes about four to six months to replace itself fully. Toenails grow significantly slower, often requiring 12 to 18 months for full regeneration. This difference in speed is due to reduced blood circulation in the toes compared to the fingers.
While the new nail is growing, protecting the exposed nail bed is important to prevent discomfort and complications. Keep the area clean and dry. A thin layer of petroleum jelly covered with an adhesive bandage can protect the sensitive tissue.
If a portion of the nail is detached but still partially attached, trim the loose part to prevent catching and further trauma. If the nail has been completely lost, the empty space must be protected until the new plate is strong enough to cover the nail bed.
Signs of Serious Injury
Most minor nail injuries can be managed at home, but certain signs indicate that professional medical evaluation is necessary. Persistent or severe throbbing pain not relieved by over-the-counter medication is a cause for concern. A large subungual hematoma—pooling blood under the nail covering more than 50% of the nail bed—may require drainage to relieve pressure.
Signs of a developing infection should also prompt a visit to a healthcare provider. These signs include increasing redness, swelling, warmth around the nail folds, or pus draining from the wound. Deep lacerations to the nail bed or injuries associated with a potential bone fracture, such as a severely crushed fingertip, require immediate medical attention.