When I think of Lady Gaga, besides the mental image of the “meat dress” and the like, I can’t help but ponder those incredible, unwearable feats of fashion engineering known as the “Armadillo” shoes by the late, great Alexander McQueen (see http://www.vogue.co.uk/blogs/the-vogue-blog/articles/091026-alexander-mc... 
In my mind, those 10- to 12-inch high shoes are a cross between ballet pointe shoes and the footwear I have seen in the Shoe Museum at Temple University. When considering both the Armadillo shoes and pointe shoes, my mind is filled with the various toenail dystrophies that can occur. What are some of the signs of common toenail trauma that can be induced by shoes?
After a few hours of a patient wearing a shoe like the Armadillo, practitioners would see a subungual hematoma or two on the fashionista’s toes. Over time and the repeated trauma of the shoe, we would see hyperkeratosis of the nails much like one would see in a jogger’s toe. Considering there are only a limited number of the Armadillo shoes in existence, let us consider general nail trauma that might be induced by shoes.
Beau’s lines. These are depressions that run transversely across the nail plate. The width of the depression correlates with the length of the insult to the proximal nail matrix.1 Beau’s lines can occur singly (one event or illness) or with multiple bands (multiple repeated trauma). I see this nail manifestation in people who chronically get pedicures, those who play basketball or tennis (or any sport that stops and starts with the nails hitting the front of the shoe), and those who wear tight fitting shoes and clogs.
Onycholysis. Onycholysis is the separation of the nail plate from the nail bed. According to Bodman, it is caused by repetitive microtrauma, which can be caused by ill-fitting shoe gear and subsequent nail unit impingement.2 As his study notes, this commonly occurs not only in longer toes, but also in the hallucal and fifth toenails especially in “slip-on shoes that hug the heels and grab the toes to stay on the foot.”
One may also see onycholysis in patients who have hallux limitus and compensate by increased motion in the hallux interphalangeal joint, which ultimately causes impingement of the nail against the toe box.
Personally, I also see distal onycholysis in patients who chronically get pedicures and, in my clinical research, patients who have the mildest presentation of onychomycosis.
Onychoatrophia. This condition typically occurs in the fifth toes and is a size and thickness reduction of the nail plate. Onychoatrophia may be caused by shoe induced microtrauma and other causes include peripheral vascular disease or lichen planus. The condition also may have a congenital origin.
In the office, when patients have presented with these onychodystrophies, the patient usually feels the affected nail is onychomycotic. While onycholysis can be the starting point for onychomycosis, Beau’s lines can occur in fungal nails and onychoatrophia on the fifth toes may appear similar to nail fungus. It is important for the practitioner to distinguish between these traumatically induced deformities of the nail unit and true dermatophyte infection.
Besides obtaining a history of everyday footgear, the practitioner can send the nail specimen for periodic acid-Schiff (PAS) stain or KOH/fungal culture to determine if the nail is infected. When dealing with more of the cosmetic side of these dystrophies such as Beau’s lines, it is useful to file the nail and use a ridge filler or another topical nail product in addition to changing the offending shoegear.
1. Zaiac MN, Daniel CR. Nails in systemic disease. Dermatologic Therapy 2002 June; 15(2):99-106.
2. Bodman MA. Nail Dystrophies. Clin Podiatr Med Surg 2004 Oct; 21(4):663-87, viii.