Foot Drop


Patient is unable to walk on his heels and cannot dorsiflex his foot.

Possible causes:

  • common peroneal palsy including trauma
  • sciatic nerve palsy
  • L4, L5 root lesion
  • peripheral motor neuropathy, e.g. alcoholic,DM
  • distal myopathy
  • motor neurone disease

Clinical indicator of site of lesion: testing the ankle jerk.

Absent Ankle Jerk = L5 lesion is likely.

A normal ankle jerk indicates a possible common peroneal palsy.

The ankle jerk will be increased in an upper motor neurone lesion.

Common peroneal nerve palsy affects motor supply to the muscles of the anterior and lateral compartments of the leg. It is the most commonly damaged nerve in the lower limb as it traverses the lateral aspect of the head of the fibula. (plaster casts, kneeling,prolonged lying on it.)

Recovery occurs within a few weeks when the cause is simple compression. Full knee flexion should be avoided as in kneeling or squatting, and the patient should not sit with the legs crossed over the unaffected leg. To prevent foot drop the patient should wear an aluminium night-shoe at night and during the day, a shoe with plastic inserts. Surgical exploration is indicated if the weakness progresses or fails to resolve within 1-2 months, or if there is an obvious local lesion.

Sciatic nerve palsy affects motor supply to hamstrings and all muscles of the leg and foot plus sensation to the lateral part of the leg below the knee, including the foot. Damage arises from misplaced gluteal injections, pelvic disease and severe trauma to the hip. Nerve entrapment as a cause is very rare.

Dropping of the foot and contracture of the calf muscles should be prevented as for Common Peroneal injury above.


To Neurology might be indicated if the site of the palsy is not clear or an Upper Motor neurone lesion suspected.

Peroneal nerve palsies secondary to trauma are common, and if recovering do not need referral

For night shoe/shoe inserts refer to orthotics or physiotherapy