Trench foot: a relatively rare condition in tropical countries – a case report

Introduction

In 2012, Delhi experienced extreme cold conditions during the winter months. Trench foot, which is practically unknown in this part of India, posed a diagnostic dilemma. The differential diagnoses were gangrene (embolic), compartment syndrome and external constriction band. We present here the manifestations of trench foot and its management. The aim of the report is to create awareness of this condition and a possible, although rare, differential diagnosis in tropical regions.

Case report

An 8-year-old girl presented to our hospital with subluxation of right hip joint as a sequelae septic arthritis of hip in December 2012. The patient was put on skeletal traction for 1 week and following reduction of the hip joint, one and a half hip spica was prescribed for 3 weeks to maintain reduction. Parents reported back to hospital 12 days after discharge with complaints of discoloration and swelling of toes (Figure 1A). The patient reported no pain in the extremities or toes. On clinical examination, there was swelling and discoloration of toes. On first look, it had a similar appearance to dry gangrene and the hip spica was immediately removed. Toes were cold on palpation, there was no pain on passive dorsiflexion of toes and ankle, and calf muscles were supple. There were no other signs of compartment syndrome. Posterior tibial and dorsalis pedis artery were palpable. No active toe movements were present and ankle movements were restricted. There was no distinct zone of demarcation. Rapid rewarming of the foot was done using heated blanket. The toes went pink gradually starting proximal to distal. Reactionary blisters developed over the toes, dorsum and sole of the foot the following morning and child then reported a painful extremity. Blisters were large and fluid-filled, and were likely to rupture spontaneously. The blisters were aspirated, a sterile dressing applied, a posterior splint was applied and the limb was kept warm. The patient was put on antibiotics as some blisters had already ruptured and her skin was raw. Gradually over 3 weeks the swelling decreased, the blisters healed and full foot function with active toe movements was regained (Figure 1c). OPEN IN VIEWER

Discussion

Frostbite is due to a dry-cold condition that is known to occur at subzero temperature and is commonly seen in polar regions and at high altitudes.^1,2 It is uncommon in tropical regions such as Delhi; however, trench foot is a non-freezing injury caused by prolonged exposure to damp, cold, unsanitary conditions. Trench foot does not require freezing temperatures, and can occur with temperatures of up to 60°F (15.5℃). ³ Tight-fitting, constricting footwear exacerbate the condition. ³

In this case, a differential diagnosis of gangrene (embolic), compartment syndrome and external constriction band (due to tight padding or plaster cast bandage) was kept initially. However, these pathologies were negated on examination as on removal of cast no distinct constriction band was found and there was no circumferential erythema or constriction mark over the extremity. Gangrene was unlikely as distal pulses (posterior tibial and dorsalis pedis artery) were palpable and there was no distinct zone of demarcation. Compartment syndrome was excluded as on passive stretching of toes and dorsiflexion of the ankle, tenderness was not elicited and calf muscles were supple. After exclusion of these conditions, a cold aetiology for the pathology was suspected and our case appeared to be a trench foot.

The etiopathogenesis in trench foot is cold injury to peripheral limb tissues. In the early stages, blood vessels constrict in cold, moist conditions resulting in a lack of oxygen to the tissues. The foot becomes cold, numb and mildly swollen, painful and discoloured. If allowed to progress, tissue and nerve damage occur. ³ The symptoms of trench foot may include pain, itching, numbness and swelling. The affected foot may appear red or blotchy (red and pale areas mixed together) or even bluish-black with advanced injury. With severe trench foot, the tissue dies and sloughs off, and the development of gangrene can occur, sometimes requiring amputation. ³

Risk of its development increased as the child was recumbent on hip spica causing sluggish venous return, and extreme cold weather further left peripheral circulation compromised. Lack of active toe movements by the child further hampered the distal circulation.

Trench foot is a rare diagnosis in India and thus awareness on the part of clinician is must. Several of our patients reside in far-off rural areas and travel long distances to visit hospitals even in extreme winter. Parents of children on hip spica should be educated to keep the limb warm and the child should be encouraged to continue with active toe movements. Once trench foot develops, rapid ‘warm bath rewarming’ is the treatment of choice. Warm bath rewarming is best done in a bath of 40–42℃ of moving water (re-warming rate: ∼ 1–2℃/h), however in mild to moderate cases re-warming by warm blanket or forced hot air can be done. ⁴ Trench foot of the extremities of children may produce serious changes in the bony structure in later years; ² however, these changes are more common when infection and soft-tissue damage leave the bone exposed. The child in our case made an uneventful initial recovery.