What is the pathophysiology of nailbed injuries?

Updated: Sep 27, 2017
  • Author: Darrell Sutijono, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
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Answer

Longitudinal nail growth takes between 70 and 160 days to cover the entire length of the nail. After an injury, nail growth is stunted or absent for up to 21 days. The nail then grows rapidly for approximately the next 50 days and then slows again before a normal and sustained growth rate resumes. These relative accelerations and slowdowns in nail growth create the characteristic lump that is often observed on most nails that regrow after trauma.

As a result of scar tissue being unable to produce nail material, damage to specific components of the perionychium will lead to characteristic defects during regrowth of the posttraumatic nail. A scar of the dorsal roof of the nail fold creates a dull streak on the nail surface, while a scar of the germinal matrix may cause a split or absent nail, and a scar in the sterile matrix results in a split or nonadherent nail beyond the scar.

The nailbed is supplied by two volar arterial arches that are anastomoses between digital arteries of the finger or toe, just above the periosteum of the distal phalanx. Venous drainage coalesces in the proximal nailbed and proximal to the nail fold and drains over the dorsum of the finger. Abundant lymphatic vessels are present in the nailbed. The perionychium is innervated by the dorsal branches of the paired digital nerves, one to the nail fold, one to the fingertip, and one to the pulp.


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