The growth of a nail in an asymmetrical or slanted direction, known as nail deviation, affects both fingernails and toenails. While often appearing cosmetic, this deviation can indicate an underlying physical problem or lead to painful complications like ingrown nails. Understanding why the nail plate is pushed off its straight course is the first step toward management. The causes of slanting are rooted in either external forces acting upon the digit or internal changes within the nail unit.
The Anatomy of Nail Growth
The direction and shape of a healthy nail are determined by the nail matrix, which acts as the growth center for the nail plate. This specialized tissue is located beneath the skin at the base of the nail; the visible crescent, or lunula, is only a small part of it. The germinal matrix produces the keratin cells that form the nail plate, which are continuously generated and pushed forward, hardening to create a smooth, uniformly shaped nail. For the nail to grow straight, the matrix must be perfectly aligned and undamaged. Even slight misalignment or chronic irritation causes new nail cells to be produced on an uneven plane, resulting in a slanted or curved growth direction.
Mechanical Causes and External Pressure
Many instances of slanted nail growth are traceable to physical forces applied to the toe or finger. Acute trauma, such as a crushing injury, can damage the delicate matrix cells. This damage can result in permanent structural changes, causing the nail to grow out with a ridge, a dent, or a persistent sideways slant. Chronic, repetitive pressure is particularly damaging for toenails, often caused by ill-fitting footwear. Shoes that are too narrow or shallow exert uneven force, physically deforming the underlying nail unit. This sustained pressure can lead to the classic “pincer nail” shape, where the edges curve inward and the nail appears slanted or severely bowed.
Grooming and Habitual Stress
Poor grooming and persistent habits also contribute to mechanical distortion of the nail matrix. Aggressively pushing back the cuticle or habitually picking at the skin around the nail places stress directly over the matrix area. This constant irritation interferes with the cell production process, resulting in a wavy or unevenly growing nail plate. Cutting the nail much shorter on one side than the other can also encourage an uneven growth pattern.
Internal Factors and Underlying Conditions
Slanted growth can originate from structural issues deeper within the digit or from systemic health conditions. Anatomical variations, such as a curved nail bed or an angled phalanx bone, can predispose an individual to non-straight growth. This type of deviation is often genetic and may manifest as a mild slant on multiple digits.
Bony Projections
A complex internal cause is the development of an abnormal bony growth, such as a subungual exostosis (a type of bone spur). This benign projection forms on the tip of the phalanx bone, typically of the big toe, located beneath the nail bed. The spur pushes up against the nail bed and matrix, physically forcing the nail plate to grow upward and often severely to one side.
Medical Conditions
Underlying medical conditions can also distort the nail’s growth path. Fungal infections (onychomycosis) often begin in the nail bed and cause it to thicken significantly. This hyperkeratosis, or excessive build-up of keratin debris, detaches the nail plate and forces it into a thickened, discolored, and misaligned position. Chronic skin diseases like psoriasis can involve the nail matrix, resulting in a crumbling, pitted, or distorted nail that grows unevenly.
Corrective Techniques and Management
Managing a slanted nail starts with eliminating external pressure and adopting proper nail care practices. Toenails should be trimmed straight across rather than rounded at the edges to prevent the nail from curving into the skin. Wearing footwear that provides ample space for the toes relieves the chronic pressure that leads to pincer-type curvature.
For severely curved or slanted nails, a podiatrist may recommend professional solutions like toenail bracing (Orthonyxia). This method involves applying a small brace to the nail surface to gently apply tension, training the nail to flatten and grow in a straighter direction over several months.
If the nail is painful, severely thickened, discolored, or if the slant is a sudden change, consultation with a healthcare professional is necessary. A doctor or podiatrist can diagnose issues requiring medical intervention, such as a chronic fungal infection or a bone spur. Addressing the underlying cause is the most effective way to encourage the nail to return to a normal, straight trajectory.