Q. How do I tell a corn from a callus?

A corn forms where pressure gathers on a small area; a callus forms from pressure spread over a wider area.

• There is a sharp, stabbing pain when you walk
• A core is visible at the centre of the lesion
• Only two or three are seen, at the spots taking pressure

These point to a corn. Left alone, pain makes you step on the side that does not hurt, and as the gait changes, load falls on the ankle, knee and hip. As muscles stiffen and weaken, it can lead on to claw toes, Achilles tendon damage or plantar fasciitis.