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what causes drop foot

Foot drop (or “drop foot”) is usually caused by a problem with the nerves or muscles that lift the front of your foot, most often the peroneal nerve or the L5 nerve root in the lower spine.

What is drop foot?

Drop foot is a sign, not a disease by itself. It means you can’t properly lift the front of your foot (dorsiflex) when walking, so your toes may drag and you might compensate by lifting your knee higher than normal.

Main causes of drop foot

1. Nerve injury (most common)

Damage to the nerve that controls the muscles lifting your foot is the leading cause.

Common patterns:

  • Peroneal nerve compression or injury around the knee or fibular head (outer side of the leg), for example:
    • Habitual leg crossing for long periods.
* Prolonged squatting or kneeling (gardening, construction, certain jobs).

* Tight plaster cast or brace near the knee.

* Direct trauma, such as fractures or surgery around the knee or fibula.
  • L5 radiculopathy (nerve root pinched in the lower spine), often from:
    • Lumbar disc herniation.
    • Degenerative changes or spinal stenosis.
  • Peripheral neuropathy , where many nerves are damaged, commonly from:
    • Diabetes.
    • Long‑term alcohol misuse, toxins, or certain medications.

Think of the peroneal nerve like a cable running in a shallow groove by the knee; because it’s close to the surface, it’s easy to “crush” with pressure, leading to sudden weakness.

2. Brain and spinal cord disorders

Anything that disturbs the brain or spinal cord pathways that send signals to the foot muscles can cause drop foot.

Conditions include:

  • Stroke.
  • Multiple sclerosis (MS).
  • Cerebral palsy.
  • Motor neuron disease / ALS (Lou Gehrig’s disease).
  • Spinal cord injury or tumors affecting the relevant levels.

In these cases, the problem is “upstream”: the muscles and peripheral nerves may be intact, but the control center or pathways are damaged.

3. Muscle disorders

If the muscles that lift your foot progressively weaken, you can also develop drop foot.

Examples:

  • Muscular dystrophies.
  • Motor neuron diseases (affecting both nerves and muscles).
  • Previous polio or post‑polio syndrome.

These conditions often cause other muscle weakness as well, not just in the foot.

4. Other and less common causes

Several other mechanisms can lead to drop foot, often by affecting nerves, muscles, or both.

They include:

  • Tumors pressing on the nerve at the knee, along the leg, or in the spine.
  • Bone metastasis or growths around the fibular head.
  • Infections or inflammatory diseases affecting nerves.
  • Electrolyte problems or systemic illnesses that worsen existing nerve damage.
  • Functional/“nonorganic” neurological disorders, where the structure is intact but movement control is disturbed.

Everyday triggers and risk factors

Some causes are related to posture or activities that put prolonged pressure on the nerve.

Common real‑world scenarios:

  • Sitting cross‑legged for hours (for example, at work or in front of the TV) compressing the peroneal nerve.
  • Long surgeries or hospital stays where the leg is held in one position and not moved.
  • Wearing knee‑high casts or splints that are too tight.
  • Repetitive kneeling or squatting on hard surfaces.

An example: a healthy person spends an afternoon squatting while tiling a floor, wakes up the next day unable to lift the front of the foot due to temporary peroneal nerve compression.

When to worry and what to do

Drop foot should always be evaluated promptly, because some causes are reversible if treated early.

You should seek medical care urgently if:

  • The weakness started suddenly, especially with other symptoms like facial droop, trouble speaking, or loss of balance (possible stroke).
  • You have back pain with leg weakness or numbness, or loss of bladder/bowel control (possible serious spinal compression).
  • You recently had trauma, surgery, or a tight cast on the leg or knee.

Typical evaluation may include:

  • Detailed neurological and musculoskeletal exam.
  • Imaging (such as MRI of the lumbar spine or knee) if a structural problem is suspected.
  • Nerve conduction studies and EMG to localize nerve damage.

Treatment focuses on fixing the underlying cause where possible, plus supporting walking and safety with braces, physiotherapy, and sometimes surgery (e.g., nerve or tendon transfer) if the weakness does not recover.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.