GPAtlas🧭 When to suspect foot drop
Foot drop is weakness of dorsiflexion – the action of lifting the front of the foot and toes upward.
• The patient catches or drags the toes and trips easily.
• The patient often compensates with a high-stepping (steppage) gait, lifting the knee higher than usual to clear the floor.
Foot drop is a clinical sign, not a diagnosis: localise the lesion and identify the cause.
Consider foot drop in any patient presenting with new walking difficulty, unexplained trips, or falls.
• The commonest cause of a spontaneous, painless, unilateral foot drop is compression of the common peroneal (fibular) nerve where it winds superficially around the neck of the fibula at the knee.
• The main differential is an L5 radiculopathy (compression of the fifth lumbar nerve root in the spine).
• Distinguishing these at the bedside – and excluding the dangerous mimics below – is the core skill.
| Site/cause | How to recognise it |
|---|---|
| Common peroneal nerve (at the fibular neck) – commonest | • Weak dorsiflexion and eversion • Inversion preserved • Ankle reflex preserved • Sensory loss over the dorsum of the foot and outer shin • Triggers: leg crossing, squatting, prolonged kneeling, a below-knee cast, recent knee surgery, or rapid weight loss |
| L5 radiculopathy (spinal nerve root) | • Weak dorsiflexion and eversion plus weak inversion and hip abduction • Back, buttock or leg pain is common • Ankle reflex may be reduced • Back pain with weak inversion points here, not to the peroneal nerve |
| Sciatic nerve lesion | • A peroneal-type pattern plus weakness beyond the peroneal territory (e.g. knee flexion), with pain in the back of the thigh and calf • Often follows hip surgery, an injection injury, or trauma |
| Central or upper motor neurone (stroke, multiple sclerosis, cord lesion) | Look for upper motor neurone signs – increased tone, brisk reflexes, an upgoing plantar – usually with other neurological deficits. |
| Peripheral polyneuropathy (diabetes, alcohol, vitamin B12 deficiency) | • Often bilateral and distal with glove-and-stocking sensory loss • Suspect when there is no compressive trigger |
Source: BMJ Clinical Review · NICE NG59
🔒 Sign up free to read the full topic
You're viewing a free preview. Create a free account to unlock the rest.
Sign up free →Sample topics are open to everyone in the Free Sample Bundle.