How To Address Nail Bed Injuries
Injuries involving the toe nail bed and adjacent tissues are very common. Acute injuries to these structures are frequently caused by dropping a heavy object on the toe or by stubbing the toe into a solid object. Less common mechanisms of acute injury include nail bed lacerations and puncture wounds. Chronic nail trauma is usually caused by repetitive mechanical pressure associated with hammertoe or claw toe deformities aggravated by weightbearing and shoe gear contact. This can also lead to toe nail and bed hyperkeratosis and nail plate dystrophy.
Failure to identify and repair an acute nail bed defect in a timely fashion may result in less than satisfactory nail plate regeneration. This would be due to the formation of a nail bed scar that prevents plate adherence to the bed and the subsequent development of onycholysis of the newly formed nail plate.
Clinicians can provide appropriate acute care of most nail bed injuries in the office or emergency department. When it comes to nail bed injuries that are proximal to the lunula, those that are heavily contaminated or infected, or nail bed injuries among patients with less than optimal vascular status or uncontrolled systemic disease, it may be best to treat these injuries in the operating room.
Functional as well as cosmetic defects can develop following injuries involving the nail bed and associated structures (also see “An Overview Of Nail Anatomy And Physiology” below). Sequellae of such injuries include permanent nail plate thickening and discoloration, distorted orientation and onychocryptosis, and chronic onycholysis with exposure of the subungual space and nail bed. It is not uncommon to observe a patient who relates the development of a deformed or mycotic toenail following an injury wherein a subungual hematoma developed secondary to disruption of the nail bed.
Baden has described arrest of nail plate growth for up to three weeks following injury to the nail bed or significant systemic disease.4 This results in the development of a Beau’s line that involves relative thickening of the nail plate proximal and distal to a visibly thinner transverse line secondary to the temporary arrest of nail plate production. Injuries that simultaneously disrupt the proximal portion of the nail bed and the proximal nail fold (PNF) may heal with the nail fold adherent to the bed, thereby inhibiting matrix function at the site of the adhesion and resulting in a split nail (canaliformis) deformity.
An Overview Of Nail Anatomy And Physiology
The perionychium consists of the proximal nail fold (PNF), medial and lateral nail grooves and folds, the nail matrix and the nail bed.1 The nail plate is secured proximally in the groove of the PNF, where the stratum corneum of the PNF extends distally over the dorsum of the nail plate as the cuticle. The cuticle acts to seal the plate into the adjacent folds. The plate itself originates from the germinative matrix situated deep to the PNF and extending distally to the level corresponding to the distal margin of the lunula.