Concept
An ingrown nail, also known as onychocryptosis from ὄνυξ () 'nail' and κρυπτός () 'hidden', is a common form of nail disease. It is an often painful condition in which the nail grows so that it cuts into one or both sides of the paronychium or nail bed. While ingrown nails can occur in the nails of both the hands and the feet, they occur most commonly with the toenails (as opposed to fingernails), and for the most part are only problematic and painful on the big toe. A common conception is that the nail enters into the paronychium, but an "ingrown toenail" can simply be overgrown toe skin. The condition starts first from a microbial inflammation of the paronychium, and then a granuloma, which results in a nail buried inside of the granuloma. A true ingrown toenail is caused by actual penetration of flesh by a sliver of toenail. Symptoms of an ingrown nail include pain along the margins of the nail (caused by hypergranulation that occurs around the aforementioned margins), worsening of pain when wearing tight footwear, and sensitivity to pressure of any kind, even the weight of bedsheets. Bumping of an affected toe can produce sharp and even excruciating pain as the tissue is punctured further by the nail. By the very nature of the condition, ingrown nails become easily infected unless special care is taken early to treat the condition by keeping the area clean. Signs of infection include redness and swelling of the area around the nail, drainage of pus and watery discharge tinged with blood. The main symptom is swelling at the base of the nail on the ingrowing side (though it may be both sides). Onychocryptosis should not be confused with a similar nail disorder, convex nail, nor with other painful conditions such as involuted nails, nor with the presence of small corns, callus or debris down the nail sulci (grooves on either side). The main contributor to onychocryptosis is footwear, particularly ill-fitting shoes with inadequate toe box room and tight stockings that apply pressure to the top or side of the foot.