Foot drop is tested through a combination of physical strength checks, walking observations, and sensory exams that can happen both in a doctor’s office and, to a degree, at home. The simplest screening test is the heel walk: if you can’t lift the front of your foot while walking on your heels, that’s a strong signal of dorsiflexion weakness. From there, more targeted exams help pinpoint how severe it is and where the problem originates.
The Heel Walk Test
This is the quickest way to check for foot drop, and you can try it yourself. Stand on a flat surface and attempt to walk forward on your heels only, keeping the balls of your feet and toes lifted off the ground. A person with normal ankle strength can do this without difficulty. If you can’t keep your toes up, or one foot slaps back down to the floor, that side likely has weakness in the muscles that lift the foot.
Clinicians use the heel walk as a fast screening tool during neurological exams because it isolates the same muscle group (the tibialis anterior) that fails in foot drop. It’s not a definitive diagnosis on its own, but a failed heel walk is one of the clearest red flags.
Manual Muscle Strength Testing
In a clinical setting, a provider will test how strong your ankle dorsiflexion is by having you pull your foot upward while they push against it. This is scored on a standardized 0 to 5 scale:
- Grade 0: No muscle contraction at all.
- Grade 1: A faint contraction can be felt in the muscle or tendon, but the foot doesn’t visibly move.
- Grade 2: The foot moves through its full range of motion, but only when gravity is eliminated (for instance, with the leg positioned sideways).
- Grade 3: The foot lifts against gravity and holds position, but can’t resist any added pressure from the examiner’s hand.
- Grade 4: The foot holds against moderate resistance.
- Grade 5: Full, normal strength.
Foot drop typically shows up as a grade 3 or below. The specific score matters because it helps track whether your strength is improving or worsening over time, and it influences treatment decisions like whether a brace or surgery is appropriate.
Watching Your Walk
A provider will also watch you walk normally across the room. Foot drop creates a distinctive pattern called steppage gait: because the foot can’t lift during the swing phase of walking, the hip and knee flex much higher than normal to keep the toes from dragging on the ground. It sometimes looks like marching or climbing invisible stairs. In milder cases, you might not hike the knee much but instead scuff or drag the toe, which can cause tripping and falls. The foot also tends to land flat rather than striking heel-first, which is a subtle but reliable sign.
Sensory Checks
Foot drop is rarely just a motor problem. The peroneal nerve, which controls the muscles that lift your foot, also carries sensation from specific areas. Your provider will use a light touch or a pin to test feeling on the top (dorsum) of your foot, the webspace between your toes, and the outer lower third of your shin. Numbness or tingling in these areas points to peroneal nerve involvement. If sensation is normal in those spots but abnormal elsewhere, the problem may be coming from a different nerve or from the spine.
Pinpointing the Cause
One of the most important parts of testing for foot drop is figuring out why it’s happening, because treatment depends entirely on the source. The two most common culprits are peroneal nerve compression at the knee and an L5 nerve root problem in the lower back. Both can cause the same inability to lift the foot, so distinguishing them requires a few targeted checks.
The key differentiator is foot inversion, the motion of turning your sole inward. That movement is controlled by a muscle (the tibialis posterior) that gets its nerve supply from the L5 spinal root but not from the peroneal nerve. So if you have foot drop and weak inversion, the problem is more likely in your spine. If inversion is strong but you’re weak when trying to turn the foot outward (eversion), a peroneal nerve issue is more likely.
A provider may also tap over the bony bump on the outer side of your knee, just below the kneecap, where the peroneal nerve wraps around the fibula bone. This is called a Tinel’s test. If tapping that spot triggers tingling or an electric sensation shooting into the top of your foot, it suggests the nerve is irritated or compressed right at that location.
Nerve Conduction and EMG Studies
When the physical exam doesn’t give a clear answer, or when the severity of nerve damage needs to be measured precisely, electrodiagnostic testing is the next step. This involves two parts that are usually done together.
Nerve conduction studies send small electrical impulses along the peroneal nerve and measure how fast the signal travels and how strong it is when it arrives at the muscle. Normal conduction velocity in the peroneal nerve is above 43 meters per second. If the signal slows significantly as it passes behind the fibular head at the knee, that localizes the compression to that exact spot. A drop in signal strength greater than about 36% between stimulation points also suggests a problem at that location.
Electromyography (EMG) involves inserting a thin needle into the affected muscles to listen to their electrical activity. Healthy muscles at rest are electrically quiet. Muscles that have lost their nerve supply produce abnormal spontaneous activity. The pattern of which muscles show abnormalities helps confirm whether the damage is at the peroneal nerve, the sciatic nerve higher up, or the L5 nerve root. For example, testing a small muscle in the back of the thigh that receives its nerve supply from the peroneal branch of the sciatic nerve can distinguish a problem at the knee from one higher up in the leg.
Imaging Tests
If the exam and electrical studies suggest the cause is in the spine rather than the peripheral nerve, an MRI of the lumbar spine can show disc herniations or other structures pressing on the L5 nerve root. If the peroneal nerve itself is the concern, an MRI or ultrasound of the knee area can sometimes reveal a cyst, mass, or other structural cause of compression. Imaging doesn’t test the foot drop itself, but it identifies treatable causes that the other tests have narrowed down.
What You Can Check at Home
While a full diagnosis requires professional evaluation, a few things are worth noting before your appointment. Try the heel walk on both sides and compare. Test whether you can pull your foot up toward your shin against your own hand’s resistance. Check for numbness by lightly running a fingertip across the top of your foot and comparing it to the other side. Note whether your symptoms came on suddenly (which can suggest nerve compression, sometimes from crossing your legs or wearing a tight cast) or gradually (which may point to a spinal issue or progressive nerve condition). These observations give your provider a head start on narrowing down the cause.