Overview 

Trench foot might sound like an old wartime problem, but it is still a medical condition today. It occurs when the feet experience prolonged exposure to cold, damp and sometimes unsanitary conditions. This causes the skin and tissues to break down, heightening the risk of compromising customary body activities that keep us active and healthy.¹ 

The history of trench foot was first documented in Napoleon’s army in the early 1800s, and gained its notoriety during World War I when the condition claimed the lives of 2000 American and 75,000 British soldiers in the cold and waterlogged trenches - hence the name!² 

Due to poor blood circulation, the immediate symptoms of the condition are tingling, itching, and numbness. If the disease progresses, odour, swelling, blisters, and bacterial infections may occur. In some extreme cases, soldiers may experience pain so that they cannot walk. Amputations may be necessary to avoid the progression of the disease and other problems, including sepsis and death.¹ 

Military physicians soon discovered that by keeping the feet dry, small adjustments like routinely changing into clean socks can save more lives. Fast forward to the modern day, nonfreezing cold injury (NFCI) is the present-day classification for trench foot.³ The disease still affects hikers, fishermen, outdoor workers, and even music festival go-ers who spend a lot of time in soggy boots.⁴ The complications of trench foot can still be severe even though our medical care has significantly advanced now. To avoid the long-lasting effects of the condition with infections, tissue death, and nerve damage, prevention is the best cure.¹ Therefore, the next time you are out in cold, wet conditions, remember: dry socks could be the difference between happy feet and a serious medical issue!

Foot infections: when bacteria take over

If the feet stay wet for too long, the outer layers of the skin start to break down due to the disturbance of the natural conditions of the skin barrier. The moisture creates tiny cracks and openings developing blisters, holes, and open sores where the tissues will be exposed to bacteria, weakening the body’s innate defences by making infections a big risk especially when left untreated.¹ Infections do not always start with dramatic symptoms, but there are some key signs to look out for: 

• Any redness and swelling in the foot 
• Pain and warmth even with a slight touch to the foot
• Pus or oozing fluid seeping out of the skin 
• Chills and fevers are signs that the infection is spreading and the body is attempting to combat it
• A bad odour could indicate that tissue is deteriorating and dying 

Trench foot narrows the blood vessels which directly affects blood circulation to the toes¹. Since bacteria can grow rapidly, it becomes more challenging for the body to fight off the infection with insufficient oxygen and white blood cells reaching the foot and toes. If treatment is not received, the infection may travel from the foot up and up the leg and create life-threatening consequences by disrupting the bloodstream. Therefore, bacteria can cause a variety of infections if they penetrate the broken skin barrier:⁴ 

• Cellulitis: a painful soft tissue skin infection that causes redness, swelling, and warmth. After taking antibiotics for a day or two, the infection usually starts to resolve. However if left untreated, it can spread within deeper tissues
• Sepsis: the most deadly infection in which bacteria enter the bloodstream causing a blood infection and inflammatory damage. This results in an infection that spreads throughout the whole body and can lead to organ failure. In its worst form, the body is deprived of an adequate oxygen supply to maintain its normal function so the patient will enter septic shock, which is highly fatal⁴  

Gangrene 

When tissues in the foot die, one of the most dangerous consequences of trench foot is gangrene.¹ If the essential components that sustain our normal bodily functions become insufficient, the skin and deeper tissues will begin to decompose around the area. This is explained by a decreased supply of oxygen and nutrients in the blood flow in the foot and the dying tissue becomes a breeding ground for bacteria that induces a critical infection.⁵ 

In this scenario, the dead tissue may become black and give off a foul odour.⁵ The risk of gangrene increases significantly if trench foot is left untreated. In severe cases of gangrenous limbs, the damages are irreversible so the only solution is amputation to prevent infection from progressing onto other tissues to save the patient’s life.¹

Types of gangrene

There are three main types of gangrene that manifest in different forms, and two can originate from trench foot.⁵ Wet and dry gangrene can arise as a problem for trench foot, each with its distinctive characteristics and risks. 

Wet gangrene

In wet gangrene, tissue death spreads quickly due to a bacterial infection. Because of the pus and bacterial toxins in the skin, the afflicted area smell unpleasant and swell up a lot. 

It is the more alarming form of gangrene because bacteria can enter the bloodstream and cause sepsis, which is a potentially fatal reaction. Therefore, wet gangrene requires immediate medical attention. The typical treatment involves surgical removal of the dead tissue and strong antibiotic therapy to control the infection.⁵

Dry gangrene 

Unlike wet gangrene, dry gangrene happens more gradually without a bacterial infection. It is caused by a reduction of blood flow to the tissues as a result of peripheral artery disease or frostbite. As the tissue dies, the affected area turns dark brown, purple, or black and becomes dry and shrivelled. Dry gangrene progresses slowly, but it should still not be ignored because it may also need surgical removal to prevent future problems.⁵ 

All in all, to avoid any severe outcomes, both forms of gangrene highlight how important it is to detect and treat trench foot as soon as possible.¹ 

Long-term nerve damage

In some cases, even after trench foot recovery, the damage does not always leave and the foot may not regain its complete function.¹ One of the lasting effects is nerve damage, which can leave patients with uncomfortable or aching sensations in their feet for years or even life-long discomfort.⁶ 

When the feet experience cold and wet for a long period, the tiny blood vessels tighten up which leads to inadequate circulation and recurrent tissue damage, so the nerves in the extremities are deprived of oxygen and nutrients from the blood. This leads to peripheral neuropathy causing the nerves to deteriorate over time.³ 

Signs of permanent injury of the nerves include:⁶

• Painful cold
• Burning
• Itching
• Loss of feeling
• Tingling
• Persistent ‘pins and needles’ 

A study conducted on the UK armed services with trench foot demonstrated that the density of the nerves decreased by 91% whilst experiencing neuropathic pain.⁴ In extreme cases, the affected limb may even be paralysed.⁷ 

A person’s day-to-day activities and mobility may be greatly affected by these symptoms because even exposure to the cold or slight pressure on the feet can cause discomfort. Furthermore, it also increases higher risk of future injuries. Regarding possible treatments, topical treatments such as Lidocaine are used to anesthetise the nerves and reduce pain and electrical therapy is used to trick your brain to stop pain messages. In essence, trench foot is not just a temporary condition, but a blood vessel crisis that evolves into a chronic nerve disorder, with both systems amplifying each other’s damage.⁷ 

Summary 

Trench foot is mistakenly known as an old war-related problem but it is still a health issue in today’s society. The condition occurs when the feet are exposed to wet and cold conditions for an extended period of time. It can be further complicated by infections by bacteria, which can manifest into gangrene, sepsis, tissue loss and long-term nerve damage due to a lack of blood flow. People should know the signs of the condition and seek medical attention immediately if they develop any related symptoms to avoid further damage that may never fully heal or at the very worst, result in amputation. To speed up recovery and prevent recurrence, patients should be informed on appropriate footwear (shoes, socks, and insoles) and wound protection. Whether you are a soldier, hiker, or just someone caught in bad weather, the most important prevention advice is to avoid staying in wet and cold environments for an unnecessary amount of time, and change into dry socks!