Foot drop
Foot drop is not a disease of its own but a sign: the front of the foot stops lifting, the toes hang down, and the foot catches on the ground with every step.
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Foot drop is not a disease of its own but a sign: the front of the foot stops lifting, the toes hang down, and the foot catches on the ground with every step. One side is usually affected. The sign itself is painless and unalarming, yet the range of things behind it is enormous, from a nerve squashed during a couple of hours in an awkward position to a slipped disc or conditions best caught early. The commonest cause happens to be the mildest one and settles on its own; the trouble is that weakness of the foot alone cannot tell it apart from the rest, and that is exactly what decides whether to wait or to act.
What people notice first
Others often spot it before the person does. The walk changes in a very recognisable way: to keep the toes off the floor the knee has to swing up higher than usual, as though stepping over a low sill, and then the foot slaps down flat. Hence the complaints people arrive with.
- Tripping on level ground, especially over the edge of a rug, a threshold or the first stair.
- One shoe wearing through at the toe far faster than the other.
- Being unable to stand on the heel or to walk on heels — the foot simply drops.
- Numbness or pins and needles over the outer side of the lower leg and the top of the foot.
There may be no pain at all. If there is pain, its location matters: back pain running down the outer thigh and calf towards the big toe points to a very different level of the fault than pain felt in the lower leg itself.
Where the signal breaks
The instruction to lift the foot travels a long way: brain, nerve root in the lower back, sciatic nerve, its peroneal branch, and finally the muscles at the front of the shin. It can break anywhere along that route, and the causes group according to where.
Compression of the peroneal nerve below the knee. This is the commonest version by far. The nerve wraps round the head of the fibula immediately under the skin with no protection at all, and it is easily crushed there. The classic settings: sitting cross-legged for long stretches, working squatting or kneeling, a tight plaster cast, sleeping in an odd position after drinking, an anaesthetic or a long spell lying in hospital. Rapid weight loss deserves a separate mention: the pad of fat over the nerve thins out and the nerve becomes easier to squash.
The lower back. A disc herniation trapping the L5 root produces exactly the same weakness, though usually with back and leg pain. One detail helps to separate them: with a root problem, turning the foot inwards and moving the hip out to the side also weaken, whereas with compression below the knee those movements stay strong.
Metabolic and general causes. Diabetic polyneuropathy, vitamin B12 deficiency, heavy drinking, the effect of certain medicines. Here both feet are usually involved, symmetrically and gradually.
Inherited, muscular and brain-related causes. Charcot-Marie-Tooth disease, in which a high-arched weak foot develops over years, muscular dystrophies, spinal muscular atrophy, and equally the after-effects of a stroke, multiple sclerosis, cerebral palsy or Parkinson's disease.
There are also rare causes worth knowing about, because they are the ones missed longest. One is vasculitis damaging nerves one at a time: after the foot, a hand or the other leg starts to weaken. Another is a tumour or a ganglion cyst of the nerve itself at the head of the fibula, hinted at by a lump you can feel and by tenderness when that spot is tapped. The third is motor neurone disease, which in some people begins with foot drop and nothing else: no pain, no numbness, but muscle twitching and gradual spread to other muscle groups.
When waiting is not an option
Most of the time foot drop is something to take to a doctor in the ordinary way. But there are combinations where the clock runs in hours — with those, call an ambulance (across European countries the single number is 112) or go straight to emergency care.
- The weakness arrives together with numbness around the perineum and inner thighs, difficulty passing urine or incontinence: that is compression of the cauda equina, and it needs urgent surgery.
- The weakness comes on suddenly alongside a drooping face, slurred speech or a weak arm: these are signs of a stroke.
- The weakness builds over hours or days, climbs upwards, reaches the other leg and the hands, and the reflexes disappear.
- After an injury to the leg or heavy exertion, the calf feels bursting-tight, the pain is severe and does not ease, the skin is stretched and the foot goes numb: that is muscle compressed within its compartment.
- The weakness comes with a high temperature, severe back pain or weight loss.
Without these signs it is still worth being seen within days rather than leaving it to sort itself out: the sooner the pressure comes off, the more completely the nerve recovers.
How the cause is tracked down
Examination supplies more than half the answer. The doctor tests the strength of each individual foot movement, checks sensation and reflexes, and watches the walk. The area over the head of the fibula is felt and tapped as well: a shock shooting down into the foot says the fault lies right there. Tests follow according to the picture.
- Nerve conduction studies and electromyography — the key investigation. They show at what level and how severely the nerve is damaged, and separate a reversible squeeze of the sheath from torn fibres. One important nuance: in the first days they still show nothing, so they are done after two or three weeks, and a result taken too early misleads.
- Nerve ultrasound — quick and painless, and it finds the point of compression, a cyst or scarring.
- MRI of the lumbar spine — when the picture points to a nerve root.
- Blood tests — glucose and HbA1c, vitamin B12, markers of inflammation, and immune tests if vasculitis is suspected.
An X-ray adds little here and is mainly reserved for injuries.
What brings the step back
Treatment has two halves: remove the cause, and keep the foot from deteriorating while the nerve repairs itself.
The first half depends on the finding. Compression is lifted by changing the position, the cast or the habit of sitting cross-legged. A disc herniation is managed without surgery or operated on if the weakness is progressing. Diabetes and B12 deficiency are corrected. A cyst or scar beside the nerve is sometimes removed. If the nerve has been cut through, repair or grafting is discussed, and timing rules here too: a signal restored too late will no longer wake the muscle.
The second half is done in every case and starts straight away.
- An ankle-foot orthosis. A light splint holds the foot at a right angle and gives back a normal step the same day. There is no need to refuse it so that the muscles "work on their own": it does not hinder recovery, and it does prevent falls.
- Stretching the back of the calf. Over time a dropped foot shortens the Achilles tendon, and then even a recovered nerve cannot lift it. Daily stretching and a night splint are the most underrated part of the treatment.
- Physiotherapy. Work on the front shin muscles, balance training and retraining of the walking pattern.
- Functional electrical stimulation. A small device delivers an impulse at the right phase of the step and lifts the foot; it is used chiefly after a stroke and in multiple sclerosis.
- Tendon and joint surgery. Once it is clear the nerve will not recover, the tendon of a working muscle is transferred so that it lifts the foot, or the joint is fixed in a comfortable position.
Timescales honestly depend on the cause. A mild compression, where only the nerve sheath suffered, clears within weeks, sometimes a couple of months. If the fibres themselves have died, the nerve regrows at roughly a millimetre a day and the wait runs into many months. With brain conditions and inherited forms the goal is not cure but walking safely and confidently, and that is entirely achievable.
Staying on your feet while the foot will not obey
The risk of tripping and breaking something is higher here than people assume, and the measures against it are simple.
- Shoes with a firm heel counter, laces that hold and a non-slip sole; backless slippers and flip-flops are best put away.
- Clear the house of whatever the toes catch on: curled rug edges, cables, thresholds, things left on the floor.
- Light along the route you take at night, a handrail on the stairs, contrasting tape on the top and bottom step, a rubber-backed mat in the bathroom.
- A walking stick for the first few weeks is not an admission of frailty but insurance on uneven pavements and in crowds.
- Do not sit with your legs crossed or work squatting for long: that presses on the very same nerve. If you spend long hours lying down, make sure the outer side of the knee is not resting against anything.
- Check the foot daily: numb skin rubs raw or burns easily without your noticing in time.
Online consultation
Remotely you can settle the main question well: at what level to look for the fault and how urgent it is. The doctor will ask how it began and what happened in the days before, whether there is back pain or numbness, will want to see you walk and try walking on your heels, and will check the movements that separate a nerve root from a nerve squashed below the knee. From there they will say which tests are worth doing and within what timeframe, explain how to choose a splint and how to stretch, and go through blood results and a nerve conduction report if you already have them. The signs listed under urgent situations are not assessed through a screen: those need to be seen in person without delay.
This material is for information only and does not replace medical advice.
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