Introduction 

Trench foot is a non-freezing cold injury, synonymous with World War I, despite being referenced by armies as early as the Napoleonic Wars. This article will describe the trench foot and discuss its role in World War I, as well as in other historical conflicts. 

What is trench foot?

Definition 

Trench foot, also known as immersion foot, is a non-freezing cold injury caused by prolonged exposure to lower temperatures and wet conditions.^1,2

Trench foot is similar to conditions such as cold urticaria, chilblains, and Raynaud’s Phenomenon because these conditions are all caused by exposure to cold, but not freezing, temperatures. However, the aforementioned conditions cannot be classed as non-freezing cold injuries because they do not involve exposure to moisture.¹ 

Trench foot is also different to frostbite because trench foot occurs at temperatures above freezing temperature (0℃), whereas frostbite occurs at temperatures much lower than freezing temperature.^1,2 

Trench foot predominately affects the feet, but the legs, hands buttocks and knees can also be affected.⁵

Symptoms 

The symptoms of trench foot differ depending on the stage of the condition. 

 The first stage involves the initial exposure to cold temperatures. Symptoms include:^1,3,4

• Loss of sensation/sensitivity
• Numbness 
• Initially red, then pale or completely white extremities 
• Difficulty walking 

The second, post-exposure, stage starts after an individual is moved from a cold to a warm environment and continues during and after re-warming. Symptoms include:^1,3,4

• Extremities appear pale blue and mottled (this may be difficult to see in darker skin tones)
• Cold and numb extremities 
• Swelling 
• Delayed capillary refilling 
• Initially, a weak peripheral pulse which becomes stronger 

The third stage involves hyperemia and results in the following symptoms:^1,3,4

• The affected area becomes swollen and bright red
• Increased/stronger pulse 
• Continued delayed capillary refilling 
• Extreme pain and sensitivity but distal parts of the affected limbs may still be numb
• Severely damaged areas may have blistering, but there is usually no noticeable tissue damage
• Blistering and skin discolouration are rare but suggest imminent necrosis 

During the fourth post-hyperemia stage, the affected limbs appear normal unless, in the rare case, there is tissue necrosis. Other symptoms include:^1,3,4

• Cold or cold-sensitive limbs
• Vasoconstriction 
• Limbs that remain cold for hours despite short exposure time to cold 
• Chronic pain 
• Hyperhidrosis
• Gangrene occurs in severe cases, although this is rare

Figure 1: A severe case of trench foot.¹¹

How does trench foot develop? 

While the pathophysiology of trench foot is not well established, it has been suggested that prolonged exposure to cold temperatures causes damage to the blood vessels of the brain and spinal cord, which leads to peripheral vasoneuropathy.² 

Cold temperatures, moisture, and pressure (for example, from tight footwear) lead to increased blood flow and oedema, the injury and destruction of the capillaries and other small blood vessels.^1,2 This impairs how fluid moves through the circulatory and lymphatic systems in the foot, destroys nerves, and leads to tissue necrosis. 

Early recognition

Although trench foot was recognised as a new disease during World War I (WWI), it has affected multitudes of armies throughout history.¹⁰

One of the earliest references to trench foot was made by Dominique Jean Larrey, a French soldier who became surgeon-in-chief to Napoleon. During the winter of 1812 to 1813, the French army retreated from Russia, and having seen that soldiers experience “painful tingling…numbness [and] discomfort” in variable low temperatures, Larrey recommended slow warming and rubbing feet with snow.^6,9 A little over a hundred years later, in the winter of 1914 during WWI, medical authorities would receive reports of cases of a “not yet defined” condition and “chilled feet”, which would later be called trench foot.⁸

Trench foot during World War I

Conditions in the trenches

WWI saw the Allied Powers (Great Britain, France, Russia, United States and Italy) fight against the Central Powers (Germany, Austria-Hungry, and the Ottoman Empire) from 1914 to 1918. 

Trench warfare was a tactical strategy whereby soldiers fought from long, deep ditches. While providing cover from attacks, trenches would often flood after rain. There were only 18 days of dry weather between 25th October 1914 and 10th March 1915, and soldiers were often immersed up to their waist and even armpits in mud or cold water at near-freezing temperatures.⁷ Conditions such as these meant soldiers’ feet were constantly exposed to cold and moisture, precipitating factors of trench foot. 

Figure 2: A flooded dug-out on a front-line trench. ¹²

Role of footwear and clothing

In addition to the low temperatures and moisture, many soldiers only possessed one pair of ill-fitting boots, tight puttees, and one pair of socks and would often not remove these for several days. This meant that soldiers’ feet would have prolonged exposure to cold, dampness and constriction.⁸

Prevalence in WWI

In the winter of 1914 to 1915 alone, more than 20,000 British soldiers were treated for trench foot, ultimately resulting in the deaths of approximately 75,000 British soldiers and 2000 American soldiers by the end of WWI.^2,3,8

Between 1914 and 1918, British, French, and German armies reported 115,361, 79,465 and 12,848 cases of cold injuries, respectively.¹⁰

Medical response

Trench foot was considered a serious problem because it incapacitated “hundreds, if not thousands”, of soldiers and led to manpower shortages.⁸ In November 1914, the British Army issued Army Routine Orders in response to the increasing incidence of trench foot.⁷ As a result, many measures were implemented to prevent trench foot, including:^2,7,8

• Installation of drainage systems and duck-boards to reduce contact with moisture
• Modification of footwear to allow for circulation 
• Provision of grease and whale oil to protect against moisture 
• Foot and boot inspection for early detection of trench foot 
• Regular removal of boots and socks, and rotation schedules to minimise prolonged exposure to cold and damp

Figure 3: A Medical Officer conducts a foot inspection in a support trench.¹³

Treatment

Early treatment for trench foot prescribed by doctors includes friction with snow, cold water, oils and spirits. Later, steps were taken to keep the affected areas clean, dry, and warm, and as the understanding of trench foot evolved, doctors thereafter used various tinctures, dressings, exercises, and cleansing methods.^7,8 Amputation, in cases of severe gangrene, was seen as a last-resort treatment.⁸

Trench foot in later conflicts

World war II 

World War II (WWII) saw the Allied Powers (Great Britain, countries of the British Empire, France, the Soviet Union, and the United States) fight against the Axis Powers (Germany, Italy and Japan) from 1939 to 1945. 

The number of cold injury casualties on both sides of the war was significant, with 11,000 cases of trench foot reported by the US Military in November 1944 alone, contributing to a total of 70,000 cases experienced by American soldiers. The German army reportedly had 250,000 cases of trench foot occurring between the winter of 1941 to 1942.^3,15

A paper published in 1947 made a conservative estimate that between 50,000 to 100,000 WWII veterans would request care for, and claim disability due to, chronic trench foot.¹⁴

Korean war 

The Korean War was a conflict between North Korea and South Korea from 1950 to 1953. 

Despite the scientific understanding of trench foot evolving since WWII, trench foot still occurred. The boots worn by US troops were impermeable to moisture but led to excessive sweating during long marches. This sweat would freeze, form ice within the boots, and make it impossible to remove socks, creating the perfect conditions (cold and damp) for trench foot to develop.¹⁰

In addition to inadequate footwear, US troops were unprepared for the extreme weather conditions they would face and did not have adequate treatment programmes to address trench foot, which was mistaken for frostbite.¹⁶

Falklands war 

The Falklands War was a conflict between Argentina and Britain that took place in 1982. 

British royal marines and paratroopers were exposed to harsh, wet terrains and boggy moors, meaning their feet were often wet. They often did not have the chance to rest, dry their feet or change their socks, leading to the development of trench foot, which was experienced by 76% of one British brigade.^4,10

Trench foot today 

While our understanding of trench foot has significantly developed since WWI, research is still being carried out to gain a better understanding of its mechanism of injury and management of associated complications.^17,18

Current guidance issued by the Ministry of Defense encourages regular movement, use of waterproof clothing, avoiding over-heating and snug but not tight boots to prevent non-freezing cold injuries. They also developed a field assessment tool to use when inspecting hands and feet.¹⁹

Today, trench foot is treated with the removal and replacement of wet clothes, gradual re-warming at room temperature, elevation, rest and drying of the affected areas, in addition to antibiotics, pain relief, and early mobilisation.^1,3

Presently, trench foot is not limited to military combatants alone, with cases also occurring in the elderly and homeless.^20,21

Summary 

• While trench foot was established as a new disease, distinct from cold injuries such as frostbite, during WWI, it has long affected armies throughout history
• Trench foot is a non-freezing cold injury characterised by prolonged exposure to low (but not freezing) temperatures and moisture
• The symptoms of trench foot depend on the stage of the condition but can involve changes in sensitivity, skin colour and circulation
• Trench foot resulted in the deaths of 75,000 British and 2000 American soldiers during WWI
• An evolving understanding of trench foot has allowed for advances in its prevention and treatment since WWI