Nerve damage after knee replacement occurs in roughly 1 to 2 out of every 100 surgeries, though the exact rate depends on which nerve is affected and how damage is measured
Nerve injury is one of the known risks of knee replacement surgery, but it is not common. The most frequently damaged nerve is the saphenous nerve, which runs along the inner side of the knee and provides sensation to the skin below the knee and above the ankle. Damage to this nerve causes numbness or tingling in a patch of skin on the inner leg or foot—uncomfortable but not dangerous, and usually permanent. More serious nerve injuries, like damage to the peroneal nerve (which controls foot movement), happen in fewer than 1 in 500 cases.
The variation in reported rates comes from how surgeons define and measure nerve damage. Some studies count only nerve injuries that cause noticeable symptoms the patient reports. Others include minor changes in sensation that show up only on nerve testing. Some damage resolves on its own within weeks or months; some does not. Understanding what your surgeon means by "nerve damage" and what type of nerve is at risk helps you know what symptoms to watch for after surgery.
Key Takeaways
- Saphenous nerve damage—numbness or tingling on the inner leg or foot—happens in 1 to 2 out of 100 knee replacements and is usually permanent but not dangerous.
- Peroneal nerve damage, which affects foot movement and is more serious, occurs in fewer than 1 in 500 cases.
- Nerve damage can happen during surgery from direct injury, stretching, or pressure, or after surgery from swelling, scar tissue, or positioning during recovery.
- Most nerve injuries show up within the first few days or weeks after surgery; delayed symptoms are less common but can occur.
- Tell your surgeon when ready if you notice new numbness, tingling, weakness, or inability to lift your foot after surgery.
Why nerves get damaged during knee replacement
The surgeon must cut through skin, muscle, and tissue to reach the knee joint. Nerves run through all these layers. During the procedure, a nerve can be cut, stretched, or bruised by instruments, retractors (tools that hold tissue back), or the implant itself. The saphenous nerve is at particular risk because it lies close to the surgical path on the inner side of the knee.
Swelling after surgery can also compress nerves. The knee swells significantly in the first days and weeks, and if a nerve is in a tight space, pressure from swelling can damage it even if the surgeon did not touch it during the operation. This is why controlling swelling—through ice, elevation, and compression—matters for nerve health as well as pain and mobility.
Positioning during surgery and recovery can stretch nerves. If your leg is held in a certain position for a long time, or if you keep your knee very bent or very straight for days after surgery, nerves can be pulled and irritated. Your physical therapist will guide you on safe positioning to avoid this.
Types of nerve damage and what they feel like
Saphenous nerve damage is by far the most common. You may notice numbness, tingling, or a burning sensation on the inner side of your lower leg, inner ankle, or top of the foot. The area of numbness is usually a patch about the size of your hand. This sensation change is almost always permanent, but it does not affect your ability to walk, exercise, or use your leg. Many people adapt to it within months and stop noticing it.
Peroneal nerve damage is less common but more serious. This nerve controls the muscles that lift your foot upward. If it is damaged, you may notice foot drop—difficulty lifting the front of your foot when you walk, so your toes drag slightly. You might also feel weakness in the foot or lower leg, or numbness on the top of the foot or outer lower leg. Peroneal nerve injury can affect your gait and balance and may require a brace or additional physical therapy.
Femoral nerve damage is rare. It would cause weakness in the thigh muscle (quadriceps) or numbness on the front of the thigh. Because the quadriceps is critical for knee stability and walking, femoral nerve injury is the most disabling of the three, but it occurs in fewer than 1 in 1,000 cases.
When nerve damage shows up after surgery
Most nerve injuries are noticed within the first few days or weeks after surgery. You may feel numbness or tingling as soon as you wake up from anesthesia, or it may develop over the first one to two weeks as swelling increases. Some people do not notice the change until they start physical therapy and realize they cannot feel a certain area of skin.
Delayed nerve damage—symptoms that appear weeks or months after surgery—is less common but can happen. This is usually caused by scar tissue forming around a nerve or by a nerve being compressed as swelling resolves unevenly. If you develop new numbness, tingling, or weakness months after surgery, mention it to your surgeon even if you did not have symptoms right after the operation.
Recovery from nerve damage varies. Minor stretching or bruising may resolve within weeks or months as the nerve heals. Permanent damage—like saphenous nerve numbness—does not reverse, but the brain adapts and most people stop noticing it. Serious injuries like peroneal nerve damage may require months of physical therapy and sometimes a brace, and recovery is less predictable.
What to do if you notice nerve symptoms after surgery
Contact your surgeon or the surgical team if you notice new numbness, tingling, weakness, or inability to lift your foot after surgery. Do not wait to see if it goes away on its own. Early reporting helps your surgeon determine whether the problem is from swelling (which can sometimes be managed) or from direct nerve injury (which cannot be reversed but can be monitored).
Your surgeon may order nerve testing—called electromyography (EMG) or nerve conduction studies—to confirm which nerve is affected and how severely. These tests are not painful but take 30 to 60 minutes. They help your surgeon decide whether you need additional treatment, such as physical therapy focused on nerve recovery, a brace, or referral to a neurologist.
In the meantime, follow your physical therapy plan. Gentle movement, controlled swelling, and proper positioning all support nerve recovery. Avoid positions that stretch or compress the affected area. If you have foot drop or weakness, your therapist may recommend a brace to prevent falls and allow you to walk safely while the nerve heals.
Reducing your risk of nerve damage
You cannot eliminate the risk of nerve damage—it is an inherent part of surgery—but certain factors lower it. Surgeons with high volume and experience in knee replacement have lower complication rates overall. If you have a choice of surgeons, asking about their nerve injury rate is a reasonable question.
Before surgery, tell your surgeon if you have had previous knee surgery, significant scarring, or any history of nerve problems in that leg. These factors may increase risk slightly and help your surgeon plan the approach carefully. During recovery, follow swelling management instructions closely: ice, elevation, and compression in the first weeks reduce swelling and lower the chance of swelling-related nerve compression.
Avoid keeping your knee in one position for too long. Change positions regularly, even if it is uncomfortable. Do your prescribed physical therapy exercises, which improve circulation and reduce swelling. If you are overweight, losing weight before surgery (if time allows) reduces stress on the knee and may lower overall complication risk.
Living with permanent nerve damage
If you are left with permanent numbness from saphenous nerve damage, most people find it becomes less bothersome over time. The brain stops sending attention to the numb area, similar to how you stop noticing your socks after a few minutes. You may always have a patch of numbness, but it will not affect your ability to walk, run, or exercise.
Be aware of the numb area during activities. Because you cannot feel pain or temperature in that spot, you are at slightly higher risk of not noticing a cut, blister, or burn. Check the area regularly, especially if you have diabetes or poor circulation. Wear socks and shoes that fit well to avoid rubbing or pressure.
If you have weakness from peroneal nerve damage, a brace (called an ankle-foot orthosis or AFO) can help you walk safely and may prevent falls. Physical therapy can strengthen the muscles around the ankle and knee to compensate. Many people return to normal activities, including exercise, with a brace or without one, depending on the severity of weakness.
Frequently Asked Questions
Can nerve damage from knee replacement surgery be fixed?
Nerve damage from direct injury during surgery cannot be reversed. However, damage from stretching or swelling may recover partially or fully over weeks to months. Your surgeon can order nerve testing to determine the type and severity of injury. Physical therapy and bracing support recovery and help you adapt to permanent changes.
Is numbness after knee replacement always permanent?
Numbness from saphenous nerve damage is usually permanent, but many people stop noticing it after several months as the brain adapts. Numbness from swelling-related compression may improve as swelling decreases. Ask your surgeon whether your symptoms are likely to improve or stay the same based on the type of nerve involved and the timing of your injury.
What is the difference between nerve damage and normal post-surgery numbness?
Some numbness around the surgical incision is normal and usually temporary—it comes from cutting small skin nerves during surgery. This typically improves within weeks to months. Nerve damage causes numbness in a specific area supplied by a major nerve (like the inner leg for saphenous nerve damage) and is more likely to be permanent. Your surgeon can tell you which type you have.
Will nerve damage affect my ability to walk or exercise after knee replacement?
Saphenous nerve damage (numbness on the inner leg) does not affect walking or exercise. Peroneal nerve damage (foot drop or weakness) may require a brace and physical therapy but usually does not prevent you from returning to most activities. Femoral nerve damage (thigh weakness) is rare and most serious but still allows most people to walk and exercise with support and therapy.
Should I ask my surgeon about nerve damage risk before surgery?
Yes. Ask your surgeon about their rate of nerve injury, what nerves are at risk with your specific anatomy, and what symptoms to watch for after surgery. This conversation helps you understand your individual risk and know what to report if something feels wrong during recovery.