Which of the following nail conditions is NOT typically associated with injury?

The condition associated with onychorrhexis refers specifically to the presence of ridges or split ends along the nail plate. This condition is often a symptom of systemic issues such as nutritional deficiencies, excessive exposure to harsh chemicals, or environmental factors rather than direct injury to the nail.

In contrast, the other conditions listed—bruised nail beds, leukonychia, and nail pterygium—are typically associated with trauma or injury. Bruised nail beds result from blunt force trauma leading to bleeding under the nail. Leukonychia, often visible as white spots or lines on the nails, can occur after trauma to the nail matrix. Nail pterygium involves the growth of skin onto the nail bed and can result from damage or chronic irritation.

Thus, onychorrhexis stands out because it is generally related to non-traumatic factors, emphasizing its distinction from the other conditions linked to injuries.