Which disorder is commonly associated with the duplication of the healthy nail structure?

Onychogryphosis is a disorder that involves the thickening and curling of the nail, leading to an appearance where the nail grows unusually thick and elongated. This condition often results in the nail resembling a claw or horn, effectively representing a duplication or exaggeration of the healthy nail structure. The abnormal growth patterns can be attributed to various factors, such as neglect, trauma, or vascular disorders, which can lead to the nail's structural changes.

The duplication aspect refers to the significant changes in the nail's thickness and shape compared to normal nail growth, which makes onychogryphosis the most relevant answer regarding the disorder associated with the duplication of healthy nail structure.

In contrast, nail pterygium involves skin growth that adheres to the nail plate and doesn’t reflect a duplication of nail structure, while verruca vulgaris refers to warts caused by the human papillomavirus that appear on the skin. Nail ridges can occur as a normal part of aging or other conditions, but they do not exhibit the characteristic duplication seen in onychogryphosis. Hence, the emphasis on structural alteration and disproportionate growth firmly aligns with onychogryphosis as the correct disorder.