What is Onychauxis?
Onychauxis refers to the abnormal thickening (hypertrophy) of the nail plate. Unlike fungal infections that cause powdery debris to build up underneath the nail, onychauxis involves the actual hard keratin of the nail becoming excessively thick, making it nearly impossible to cut with standard clippers.
Clinical Presentation
Thick nails are often misdiagnosed as fungus. Here is how onychauxis differs clinically.
Visual Signs
- Uniform thickening across the entire nail plate
- Opaque, yellow, or brownish discoloration
- Loss of natural translucency
- Nail remains relatively straight (unlike Ram's horn)
Complications
- Severe pain when wearing closed-toe shoes
- Subungual ulcerations (pressure sores under the nail)
- Increased risk of secondary fungal colonization
Why Do Nails Thicken?
The nail matrix (root) produces cells at a specific rate. When the matrix is damaged or blood flow is compromised, it produces thicker, more disorganized keratin cells.
- Aging & Poor Circulation: As we age, peripheral blood flow to the toes decreases, fundamentally altering how the nail matrix functions.
- Biomechanics & Micro-trauma: Decades of wearing tight shoes or having a hammertoe that rubs against the shoe causes chronic defensive thickening.
- Systemic Disease: Diabetes and peripheral neuropathy can lead to both poor circulation and a lack of sensation, allowing trauma to go unnoticed.
- Psoriasis: Nail psoriasis causes rapid, disorganized cell turnover, leading to thickening and pitting.
Podiatric Management
Thickened nails should not be cut at home with standard clippers, as the pressure required can shatter the nail or tear it from the bed. A podiatrist will use a specialized electric micro-drill to painlessly grind the nail down to a normal thickness (debridement). This relieves shoe pressure instantly. For permanent relief in painful cases, a surgical matrixectomy can permanently remove the nail.