CORNS – How do corns occur and how can they be treated?
Corns occur in response to mechanical stresses applied to the skin of the foot. Corns are not an infection and do not have roots as is popularly believed.
Our feet undergo four main types of mechanical stresses on a day to day bases:
Compression stress results from the tissue being squashed between the ground and the boney structures in the foot. Compression also occurs when adjacent toes are pushed together in a tight shoe.
Tensile stress is the stretching of tissues under your body weight.
Shearing stress arises when two forces act in different planes and in opposite directions. It occurs when the foot moves in the shoe. The foot slides forward as the base of the shoe moves backwards.
Torsional stress is a combination of shearing with rotation. It typically occurs when the foot makes pivoting movements inside a shoe.
These stresses are often well tolerated by our feet but as soon as it goes beyond the threshold level then pathological changes occur. One such pathology, is the dreadful corn, medically known as Heloma.
Successful treatment of a corn requires identifying which stress is at work. It can often times be a combination of stresses. The stress could arise from a shoe that may not be appropriate for the foot-type of the wearer. It could also be due in an acquired misalignment in the bones and joints of the foot leading to uneven weight-bearing which causes the mechanical stress.
Removal of the corn is painless and is done with a surgical blade, without any local anaesthetic. This gives immediate relieve but the corn will reoccur if the mechanical stresses are still present. Once we combine surgical removal with the needed shoe inserts to correct the mechanical stresses the problem clears up over a few months to a year. Foot type must also be identified so as to know what types of footwear is suitable to reduce mechanical stresses.
When corns occur under the nail or between the nail and the nail sulci (side skin around nail) it is referred to as onychophosis. Onychophosis feels and looks like ingrown toenails. However, on careful inspection the differentiation can be made. See picture.
Correct diagnosis is extremely important since corns are often times incorrectly surgically excised under local anaesthetic. The corn reappears after a few weeks with the added complication of a scar which becomes very painful. Proper diagnosis is achieved by examining the leg and foot, the corn type, shoes and most importantly what happens during walking to identify and change the mechanical stresses.
The above treatments for corns are available at the Family Podiatry Centre.