Cold-weather warfare
Trench foot is a medical condition caused by prolonged exposure of the feet to damp, unsanitary, and cold conditions at temperatures as warm as for as few as 13 hours. Exposure to these environmental conditions causes deterioration and destruction of the capillaries and leads to morbidity of the surrounding flesh. Affected feet may become numb, affected by erythema (turning red) or cyanosis (turning blue) as a result of poor blood supply, and may begin emanating a decaying odour if the early stages of necrosis (tissue death) set in. As the condition worsens, feet may also begin to swell. Advanced trench foot often involves blisters and open sores, which lead to fungal infections. If left untreated, trench foot usually results in gangrene, which may require amputation. If trench foot is treated properly, complete recovery is normal, though it is marked by severe short-term pain when feeling returns. Trench foot affected tens of thousands of soldiers engaged in trench warfare in World War I. Keeping feet warm and dry, or at least changing into warm and dry replacement footgear, is the best way to avoid trench foot.
Surgical treatment of ingrown toenails
In case of recurrence after complete removal, and if the patient never felt any pain before inflammation occurred, the condition is more likely to be "onychia" which is often confused for an ingrown or ingrowing nail ("onychocryptosis"). Complete removal of the whole nail is a simple procedure. Anaesthetic is injected and the nail is removed quickly by pulling it outward from the toe. The patient can function normally right after the procedure and most of the discomfort goes away in a few days. The entire procedure can be performed in approximately 20 minutes and is less complex than the wedge resection. The nail often grows back, however, and in most cases it can cause more problems by becoming ingrown again. It can get injured by concussion and in some cases grows back too thick, too wide or deformed. This procedure can result in chronic ingrown nails causing more pain. Accordingly, in some cases as determined by a doctor, the nail matrix is coated with a chemical (usually phenol) so none of the nail will ever grow back. This is known as a permanent or full nail avulsion, or full matrixectomy, phenolisation, or full phenol avulsion. As can be seen in the images below, the nail-less toe does not look like a normal toe. Fake nails or nail varnish can still be applied to the area to provide a normal appearance. In a few cases phenolisation is not successful and has to be repeated. Podiatrists routinely warn patients of this possibility of regrowth.