FOOT DROP
If your toe is catching on stairs, that is weakness, and weakness is on a clock.
Most back pain can wait for an appointment. A foot that will not lift cannot wait indefinitely, because what is at risk is not comfort but function that does not reliably return.
What foot drop is
Foot drop is weakness of ankle and toe dorsiflexion — the muscles that lift the front of the foot. People notice it as a toe catching on stairs or carpet, a slapping sound when the foot lands, or having to lift the knee higher to clear the ground. It is often painless, which is exactly why it gets ignored.
In the lumbar spine it usually means the L5 root, most often compressed by a disc herniation or by foraminal narrowing. It can also come from a peroneal nerve compression at the knee, which is a completely different problem with a completely different treatment, and the two are separated by examination rather than assumption.
WHY THIS IS URGENT
A root under enough pressure to produce motor weakness is a root under enough pressure to be damaged. Recovery of power after prolonged severe compression is unreliable, and the window is measured in weeks rather than months. Weakness that is getting worse over days should be assessed now, not at the next available appointment. If it comes with saddle numbness or any bladder or bowel change, that is an emergency department today.
What we check
- Grade the power formally rather than by impression, so change over time is measurable.
- Heel walk. Inability to walk on the heels on one side is a clean demonstration of L5 weakness.
- Where is the numbness? Top of the foot and great toe fits L5. Numbness that spares the shin points toward a peroneal cause at the knee.
- Check the fibular head for local compression — crossed legs, a cast, prolonged squatting, significant weight loss.
- Image promptly where a root is implicated. This is one of the clear indications.
Treatment, and the honest part
Where a disc is compressing the root and weakness is progressing, surgical decompression is the appropriate answer and delay costs recovery. We will say that plainly rather than offering an injection to avoid the conversation.
Where weakness is mild and stable and the pain is the dominant problem, a targeted transforaminal injection can reduce inflammation around the root and buy the natural history time to work. That is a legitimate path, and it requires the weakness to be monitored rather than assumed stable.
Either way, an ankle-foot orthosis is worth having early. It prevents the trips and falls that do secondary damage while the root recovers, and people are often not offered one because it feels like conceding.
Common questions
Will my foot drop recover?
Often, when the compression is relieved early and the weakness was not severe or prolonged. The strongest predictors are how bad it got and how long it lasted, which is the whole argument for not waiting.
See Numbness is information about a level. Where it sits tells us which nerve..
How long can I wait?
Progressive weakness should be assessed within days. Stable mild weakness has more room, and it needs someone actually re-measuring it rather than asking how it feels.
See Almost everything on this site can wait two weeks. This page cannot..
Is it always from the back?
No. Peroneal nerve compression at the outer knee is a common alternative and is easily distinguished on examination. Diabetes and other neuropathies can also weaken dorsiflexion, usually more symmetrically.
See You can draw the line where it goes. That line is most of the diagnosis..
Related reading
- Lumbar radiculopathy
- Numbness in the foot
- When back pain is an emergency
- Before you agree to the operation
Call the same day if the weakness is increasing
Say the words “my foot is getting weaker” when you ring. That sentence changes how quickly you are seen, and it should.
12174 Natural Bridge Rd, Suite 301
St. Louis, MO 63044
At DePaul Hospital on Natural Bridge Road, inside the I-270 and I-70 interchange, on the west side of the airport.
Sources
- Carolus AE et al. The Interdisciplinary Management of Foot Drop. Deutsches Arzteblatt international, 2019. PubMed 31288916
- Daniels SP et al. MRI of Foot Drop: How We Do It. Radiology, 2018. PubMed 30152741
- Khan AA et al. Evaluation and Treatment of Foot Drop Using Nerve Transfer Techniques. Clinics in podiatric medicine and surgery, 2021. PubMed 33220746
- Bateman EA et al. Musculoskeletal mimics of lumbosacral radiculopathy. Muscle & nerve, 2025. PubMed 38726566