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.
Clubfoot
Roughly 30% of children will have recurrence. A recurrence can usually be managed with repeating the casting process. Recurrence is more common when there is poor compliance with the bracing, because the muscles around the foot can pull it back into the abnormal position. Approximately 20% of infants successfully treated with the Ponseti casting method will have an imbalance between the muscles that invert the ankle (posterior tibialis and anterior tibialis muscles) and the muscles that evert the ankle (peroneal muscles). Patients with this imbalance are more prone to recurrence. After 18 months of age, this can be addressed with surgery to transfer the anterior tibialis tendon from it medial attachment (the navicula) to a more lateral position (the lateral cuneiform) to rebalance these muscle forces. While this requires a general anesthetic and subsequent casting while the tendon heals, it is a relatively minor surgery that corrects a persistent muscle imbalance while avoiding disturbance to the joints of the foot.