Foot drop

Foot drop is a gait abnormality in which the dropping of the forefoot happens due to weakness, irritation or damage to the common fibular nerve including the sciatic nerve, or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. It is characterized by inability or impaired ability to raise the toes or raise the foot from the ankle (dorsiflexion). Foot drop may be temporary or permanent, depending on the extent of muscle weakness or paralysis and it can occur in one or both feet. In walking, the raised leg is slightly bent at the knee to prevent the foot from dragging along the ground. Foot drop can be caused by nerve damage alone or by muscle or spinal cord trauma, abnormal anatomy, toxins or disease. Toxins include organophosphorus compounds which have been used as pesticides and as a chemical agent in warfare. The poison can lead to further damage to the body such as a neurodegenerative disorder called organophosphorus induced delayed polyneuropathy. This disorder causes loss of function of the motor and sensory neuropathways. In this case, foot drop could be the result of paralysis due to neurological dysfunction. Diseases that can cause foot drop include direct hit to posterolateral neck of fibula, stroke, amyotrophic lateral sclerosis (ALS or Lou Gehrig's Disease), muscular dystrophy, Charcot Marie Tooth disease, multiple sclerosis, cerebral palsy, hereditary spastic paraplegia, Guillain–Barré syndrome and Friedreich's ataxia. It may also occur as a result of hip replacement surgery or knee ligament reconstruction surgery.

Foot drop is characterized by steppage gait. While walking, people suffering the condition drag their toes along the ground or bend their knees to lift their foot higher than usual to avoid the dragging. This serves to raise the foot high enough to prevent the toe from dragging and prevents the slapping. To accommodate the toe drop, the patient may use a characteristic tiptoe walk on the opposite leg, raising the thigh excessively, as if walking upstairs, while letting the toe drop. Other gaits such as a wide outward leg swing (to avoid lifting the thigh excessively or to turn corners in the opposite direction of the affected limb) may also indicate foot drop.

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