Onychophosis (Callus on the Sulci)

Onychophosis is also known as callus on the sulci. This condition involves the build-up of callus on the sulci. The callus forms as a protective measure on the edge of the sulcus.

Causes of onychophosis

Tight footwear that impinges the toes, and people that pronate too much may be the cause.

The inward rolling of the feet leads to rubbing and shearing on the outside of the big toes and to the inside of the big toe as it is pushed against the second toe.

The shearing can also occur on lesser toes and it manifests as a build-up of hard skin on the edges of the nails.

Onychophosis treatment

  • Treatment involves careful scalpel technique to scrape the callus clean, and to clear the side of the nail away from the sulci.
  • Change of footwear may help. Toe separators can protect the inner side of the big toe.
  • Improving foot function through exercise and orthotic correction can reduce the shearing.
  • In more severe cases, surgical removal of the side of the nail can allow the sulci more space to play. As long as the skin does not touch the side of the toe, it cannot form callus.