Numbness in the knee is primarily caused by problems with the nervous system, and is often associated with with one or more additional symptoms, such as tingling, pain, or swelling. Read more below to learn what may be causing your knee numbness and what your doctor may do to help you treat the issue.
8 most common cause(s)
Numbness and tingling in knee explained
Sensation in the knee, as in other parts of the body, includes the ability to feel light touch, temperature, vibration, and pain. Signals are carried from peripheral nerves to the spinal cord that runs through the back, and from there to the brain. Sensory signals from the knee are carried by the femoral nerve. Problems at any point along the sensory pathway from the knee can cause a feeling of numbness.
Characteristics
Depending on the cause, one or more of the following symptoms will likely be present in addition to knee numbness:
- Tingling
- Pain in the knee , other parts of the leg, and/or back
- Numbness in other parts of the leg
- Numbness in the arm and/ or face
- Swelling
- Weakness
- Muscle atrophy
What causes numbness and tingling in the knee?
Knee numbness is primarily caused by problems with the nervous system, such as damage to the femoral nerve. However, any sensation is complex and can be affected by conditions that don't directly interfere with the sensory pathway from the knee, including psychological conditions and chronic pain syndromes.
Neurological dysfunction
Causes of knee pain related to neurological dysfunction may include the following.
- Problems with the femoral nerve or its branches: This can contribute to knee numbness. This can occur via a direct injury; for example, reduced sensation in the knee is a common complication of knee replacement surgery. The femoral nerve can also be affected by compression due to an anatomical abnormality, the positioning of the leg during surgery, or tight clothing. Less commonly, abnormal functioning of the femoral nerve can occur due to diabetes.
- Arthritis: This can cause abnormalities in the sensory receptors of the knee, leading to altered sensations including numbness, tingling, and pain.
- Damage to the nerve root: Nerves of the lower extremity originate from nerve roots that emerge from the spinal cord. Damage to the nerve root that receives sensation from the knee can lead to numbness along with other sensory abnormalities. Muscle weakness, pain, and/or loss of the knee reflex will likely also be present. Nerve root damage often occurs due to abnormalities in the spine, such as degeneration caused by arthritis.
- Injury to the spinal cord itself: This can cause loss of sensation below the site of damage, which can include the knee. Specific types of sensation will be lost on one or both sides of the body according to the extent of damage to the spinal cord.
- Brain damage or stroke: Knee numbness can also occur due to damage at the highest level of the sensory pathway: the brain. A stroke (damaged brain tissue due to loss of blood flow) can present with a loss of sensation throughout one side of the body, including in the knee.
Pain syndromes
The chronic pain syndrome fibromyalgia is commonly associated with perceived numbness in various parts of the body.
Psychological factors
Because sensation is partially subjective, psychological disorders can involve the perception of numbness in areas such as the knee even when there is no physical dysfunction.
This list does not constitute medical advice and may not accurately represent what you have.
Cauda equina syndrome (rapid-onset)
Although leg pain is common and usually goes away without surgery, cauda equina syndrome, a rare disorder affecting the bundle of nerve roots (cauda equina) at the lower (lumbar) end of the spinal cord, is a surgical emergency.
Rarity: Ultra rare
Top Symptoms: lower back pain, back pain that shoots to the butt, back pain that shoots down the leg, leg weakness, thigh numbness
Urgency: Emergency medical service
Stroke or tia (transient ischemic attack)
Transient ischemic attack, or TIA, is sometimes called a "mini stroke" or a "warning stroke." Any stroke means that blood flow somewhere in the brain has been blocked by a clot.
Risk factors include smoking, obesity, and cardiovascular disease, though anyone can experience a TIA.
Symptoms are "transient," meaning they come and go within minutes because the clot dissolves or moves on its own. Stroke symptoms include weakness, numbness, and paralysis on one side of the face and/or body; slurred speech; abnormal vision; and sudden, severe headache.
A TIA does not cause permanent damage because it is over quickly. However, the patient must get treatment because a TIA is a warning that a more damaging stroke is likely to occur. Take the patient to the emergency room or call 9-1-1.
Diagnosis is made through patient history; physical examination; CT scan or MRI; and electrocardiogram.
Treatment includes anticoagulant medication to prevent further clots. Surgery to clear some of the arteries may also be recommended.
Rarity: Common
Top Symptoms: dizziness, leg numbness, arm numbness, new headache, stiff neck
Symptoms that never occur with stroke or tia (transient ischemic attack): bilateral weakness
Urgency: Emergency medical service
Spinal stenosis
The spine, or backbone, protects the spinal cord and allows people to stand and bend. Spinal stenosis causes narrowing in the spine. The narrowing puts pressure on nerves and the spinal cord and can cause pain.
Next steps including visiting a primary care physician. For this condition, a physician might suggest further investigation including imaging of the spine. Treatments may include medications, physical therapy, or braces. For severe cases, surgery is sometimes recommended.
Multiple sclerosis (MS)
Multiple sclerosis, or MS, is a disease of the central nervous system. The body's immune system attacks nerve fibers and their myelin covering. This causes irreversible scarring called "sclerosis," which interferes with the transmission of signals between the brain and the body.
The cause is unknown. It may be connected to a genetic predisposition. The disease usually appears between ages 20 to 50 and is far more common in women than in men. Other risk factors include family history; viral infections such as Epstein-Barr; having other autoimmune diseases; and smoking.
Symptoms include numbness or weakness in arms, legs, or body; partial or total loss of vision in one or both eyes; tingling or shock-like sensation, especially in the neck; tremor; and loss of coordination.
Diagnosis is made through patient history, neurological examination, blood tests, MRI, and sometimes a spinal tap.
There is no cure for MS, but treatment with corticosteroids and plasma exchange (plasmapheresis) can slow the course of the disease and manage symptoms for better quality of life.
Herniated (slipped) disk in the lower back
A herniated, ruptured, or "slipped" disc means that a vertebral disc – one of the soft pads of tissue that sit between each of the vertebral bones – has becomes squeezed out of shape. Its cushioning material has been forced against, and possibly through, the ring of fibrous tissue that normally contains it. This causes pain, numbness, and weakness in the legs.
The normal aging process causes the discs lose moisture and become thinner, making them more vulnerable to "slipping."
Most susceptible are men from ages 30 to 50. Smoking, obesity, lack of exercise, and improper lifting are also risk factors.
Symptoms include pain, weakness, numbness, and tingling in the back, leg, and foot.
Diagnosis is made through patient history, neurological examination, and MRI scan.
Treatment begins with rest, nonsteroidal anti-inflammatory drugs, physical therapy, and sometimes epidural steroid injections into the back to ease pain and inflammation.
Surgery to remove the herniated part of the disc – the part that was squeezed out of place – can also be helpful.
Rarity: Common
Top Symptoms: lower back pain, moderate back pain, back pain that shoots down the leg, back pain that gets worse when sitting, leg weakness
Urgency: Primary care doctor
Guillain-barre syndrome
Guillain-Barre syndrome is an autoimmune condition triggered by infection. It causes damage to nerves in the body that control muscles. This leads to weakness, usually starting in the legs and then progressing to the arms.
Patients with Guillain-Barre syndrome should seek immediate medical care at an ER. Nerve damage can potentially impair your ability to control your heart and lungs. You may need to be admitted to the hospital.
Diabetic neuropathy
Diabetic peripheral neuropathy is the damage done to nerve fibers in the extremities by abnormally high blood sugar. Anyone with diabetes is at risk for peripheral neuropathy, especially if the person is overweight and/or a smoker.
Symptom include pain, numbness, and burning in the hands, arms, feet, and legs; muscle weakness; loss of balance and coordination; and infections, deformities, and pain in the bones and joints of the feet.
Peripheral neuropathy can develop very serious complications, since the high blood glucose prevents any infection or damage from healing as it should. This can lead to ulcerated sores, gangrene, and amputation. For this reason, signs of peripheral neuropathy are considered a medical emergency and the person should see a medical provider as soon as possible.
Diagnosis is made through sensitivity tests and nerve conduction studies.
There is no cure for diabetic neuropathy, but the symptoms can be managed in order to slow the disease and help restore function. Treatment will include lifestyle improvements and the use of pain medication.
Chronic idiopathic peripheral neuropathy
Peripheral neuropathy refers to the feeling of numbness, tingling, and pins-and-needles sensation in the feet. Idiopathic means the cause is not known, and chronic means the condition is ongoing without getting better or worse.
The condition is most often found in people over age 60. Idiopathic neuropathy has no known cause.
Symptoms include uncomfortable numbness and tingling in the feet; difficulty standing or walking due to pain and lack of normal sensitivity; and weakness and cramping in the muscles of the feet and ankles.
Peripheral neuropathy can greatly interfere with quality of life, so a medical provider should be seen in order to treat the symptoms and reduce the discomfort.
Diagnosis is made through physical examination; blood tests to rule out other conditions; and neurologic and muscle studies such as electromyography.
Treatment involves over-the-counter pain relievers; prescription pain relievers to manage more severe pain; physical therapy and safety measures to compensate for loss of sensation in the feet; and therapeutic footwear to help with balance and walking.
Rarity: Rare
Top Symptoms: distal numbness, muscle aches, joint stiffness, numbness on both sides of body, loss of muscle mass
Urgency: Primary care doctor
Cauda equina syndrome
Although leg pain is common and usually goes away without surgery, cauda equina syndrome, a rare disorder affecting the bundle of nerve roots (cauda equina) at the lower (lumbar) end of the spinal cord, is a surgical emergency.
Call 911 immediately for an ambulance.
Prevention and treatment for a numb knee
There are multiple possible causes of knee numbness, so there are also varying treatments available. Full recovery of sensory loss is not always possible. However, often knee numbness and other associated symptoms will respond to treatment or spontaneously improve over time.
Prevention
Knee numbness can likely be alleviated with the following.
- Address nerve-related conditions: Multiple chronic medical conditions are risk factors for problems with the nervous system that can contribute to knee numbness. Uncontrolled diabetes tends to cause damage to peripheral nerves, including the femoral nerve.
- Manage other chronic conditions: Optimal management of chronic medical conditions like hypertension and elevated cholesterol will help prevent strokes.
- Avoid overly tight belts: These can compress the femoral nerve.
At-home treatments
Some at-home remedies may also be helpful to address knee numbness.
- Weight loss: When achieved through increased exercise and dietary changes, this can help with some causes of knee numbness, including arthritis and peripheral nerve damage.
- Quitting smoking: This can improve blood flow to peripheral nerves, leading to reduced sensory symptoms.
Here’s what you can do to manage it at home and understand when it might be serious enough to see a doctor.
- Pain Relievers: For associated pain or discomfort, over-the-counter options like ibuprofen or acetaminophen can help.
- Topical Creams: Applying creams containing lidocaine or capsaicin might help alleviate the sensation of numbness temporarily.
- Knee Braces: To stabilize the knee and prevent further irritation of nerves, consider using a knee brace.
Professional treatments
Professional medical treatments that may be recommended by your physician may include the following.
- Surgery: This may be required for a structural abnormality such as a tumor that is causing nerve compression.
- For strokes: Early in the course of a stroke, some people will benefit from a medication that breaks up the clot obstructing blood flow in the brain.
- Psychological interventions: These may be indicated if knee numbness is caused by psychiatric disorders or fibromyalgia.
Seek immediate treatment for the following
You should seek emergency care if you have:
- Stroke or spinal cord injury indicators: Sudden-onset of visual or speech changes, numbness in the knee along with other parts of the body, changes in bowel or bladder function, weakness, or facial droop. These symptoms could indicate that your knee numbness is being caused by a stroke or spinal cord injury.
- Nerve damage indicators: A knee injury followed by numbness, weakness, and a pale or blue appearing leg. These symptoms could indicate a significant injury with damage to nerves and/or blood vessels.
FAQs about knee numbness
Can arthritis cause knee numbness?
Yes, arthritis can be associated with loss of sensation in the knee. Arthritis in the back can compress a nerve root as it exits the spinal cord, leading to loss of sensation; depending on the specific nerve root that is affected, numbness in the knee can occur. Arthritis in the knee itself can also cause numbness due to changes in sensory receptors.
How is the cause of knee numbness diagnosed?
The diagnosis starts with a physical exam evaluating strength, sensation, and reflexes in the affected leg. Imaging of the knee, back, or brain may be required to evaluate for structural abnormalities or stroke. In addition, the function of particular nerves can be examined using tests that measure electrical activity. Blood tests will be performed if a chronic medical disease like diabetes is the suspected cause of numbness.
Can knee numbness cause numbness in the feet?
Knee numbness is unlikely to cause numbness in the feet. However, some conditions can cause loss of sensation in both the knees and the feet. Blockage of blood flow in the brain in a stroke can lead to a loss of sensation throughout one side of the body; for example, numbness could occur in the right arm, leg, and foot. A spinal cord injury, such as from a stab wound, can cause numbness throughout the body below the site of injury.
Why is my knee numb in the morning?
Knee numbness that is worst in the morning could occur if something about your sleeping position is affecting the nerve that supplies the knee or its branches. The function of a nerve can be affected by compression, either by an internal abnormality like a tumor or due to external factors like body position or tight clothing and belts.
Why is my knee numb and tingling?
Numbness and tingling are common signs of damage to a peripheral nerve. Problems with the large femoral nerve can cause sensory changes in the knee, including both numbness and tingling. Damage to the femoral nerve or its branches can be caused by compression, diabetes, injury, or arthritis.
Questions your doctor may ask about knee numbness
- Have you been experiencing any muscle weakness that is symmetrical (equal on both sides of your body)?
- Have you lost some or all of your sense of taste?
- Are you having any difficulty speaking?
- Are you having any difficulty walking?
Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.
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References
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