Fingernail Exam

Historical Overview

• Injuries to the fingertip, which often include damage to the fingernail, are common in all populations. One study found that involvement of the fingertip was present in ~50% of all hand injuries seen in EDs.¹
  • Fingertip injuries are particularly common in children, and up to 24% of these injuries also involve the nail bed.²
• Nail bed injuries that are not managed appropriately can lead to chronic gross deformities of the nail bed, nail plate, and fingertip with possible long-term functional deficits. Therefore, when the fingernail is injured, it is essential to consider potential damage to other local structures, such the distal phalanx, nail bed, soft tissue, and nerves of the fingertip.^2,3

Description

• A fingernail exam is a visual examination of the nail and its surrounding structures that is required after all fingertip injuries to detect for subungual hematomas, nail plate avulsions, nail bed lacerations, and other associated diagnoses.

Pathophysiology

• Most fingernail injuries are caused by a blunt or sharp trauma from a crushing force, such as from a heavy object, car accident, slammed door, industrial workplace mishap, or sports game. This trauma causes compression of the nail matrix, which leads to a simple or complex nail bed laceration. A cut directly to the nail bed may also be responsible.^4,5
• Sharp lacerations can occur when objects land with enough force to penetrate the nail plate, while avulsion injuries from a crushing or grinding force are also possible, and often result in partial loss of the nail bed.⁴
• That majority of fingernail injuries involve children and young adults, and ~50% of cases are associated with distal phalanx tuft fractures.^1,3
• Subungual hematomas are common after crushing injuries and nail bed trauma. This may conceal the nail bed laceration type, and deformities from the nail bed injury may not be recognized for months because the new nail takes months to grow back to the preinjury length.⁶

Instructions

1. Obtain a complete and accurate patient history, including any relevant information on the injury mechanism.
2. Perform a visual examination of the injured fingertip and fingernail, noting any signs of discoloration, blood, or swelling.
3. Ask the patient to move the distal phalanx of their injured digit to evaluate active range of motion (ROM), taking note of difficulty or pain while doing so.
4. If the patient struggles to actively move the distal phalanx, apply pressure to the fingertip to evaluate passive ROM.

Related Signs and Tests

• X-ray
  • Always required in fingertip injuries before the physical examination to assess for fractures and/or foreign bodies.³
  • Anteroposterior (AP) and lateral views are usually sufficient.²

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• A positive result occurs when the injured fingernail displays marked discoloration and blood beneath the nail plate, and the patient experiences difficulty actively and/or passively moving the distal phalanx.

• A negative result occurs when the injured fingernail does not display any marked discoloration or blood beneath the nail plate, and the patient can actively and passively move the distal phalanx.

• There are no clear guidelines regarding the diagnosis and treatment of nail bed injuries, as the literature on nail bed lacerations is often grouped with other finger injuries. As a result, despite the frequency of nail bed injuries, emergency physicians frequently misdiagnose and underestimate the severity of nail bed damage.⁶
• The fingernail is a distinct feature of the fingertip and has specialized neurovascular structures surrounding it, allowing for the unique functions of the finger, including 2-point discrimination, pincer grasp, and regulation of peripheral circulation of the fingertip. Understanding the anatomy of the fingertip is critical for appropriately evaluating injuries to this structure.²

1. Traumatol 2012;13(2):57-62. PMID: 21984203
2. Patel, L. Management of simple nail bed lacerations and subungual hematomas in the emergency department. Pediatr Emerg Care 2014;30(10):742-5.PMID: 25275357
3. Kearney, A and Canty, L. Assessment, management and treatment of acute fingertip injuries.Emerg Nurse 2016;24(3):29-34. PMID: 27286030
4. Bharathi, RR and Bajantri, B. Nail bed injuries and deformities of nail. Indian J Plast Surg 2011;44(2):197-202. PMID: 22022029
5. Inglefield, CJ, D'Arcangelo, M and Kolhe, PS. Injuries to the nail bed in childhood. J Hand Surg Br 1995;20(2):258-61. PMID: 7797986
6. Al-Qadhi, S, Chan, KJ, Fong, G, et al. Management of uncomplicated nail bed lacerations presenting to a children's emergency department. Pediatr Emerg Care 2011;27(5):379-83. PMID: 21494165