Can Sciatica Cause Knee Pain?

Knee pain is one of the most common pain conditions among adults with chronic pain in USA, being reported by approximately 20% of the patients.

The most common causes for knee pain are traumatic knee injuries (e.g.: sprained ligaments, tendonitis, cartilage tears), degenerative arthritis of the knee joint associated with aging and repeated stress on the knee resulting from heavy or lack of physical activity.

In situations where the cause of the knee pain cannot be associated with a physical injury on the knee alternative causes should be investigated. One of them can be Sciatica.

You can find more information on knee pain caused by ankle sprains here.

Why does Sciatica cause knee pain?

The sciatic nerve is the longest and largest nerve in the human body. It extends from the lower back all the way to your toes, passing through the back of your knees. The sciatic nerve is connected to several branch nerves that are then connected specific muscle groups.

The muscle groups around your knees are controlled by nerves that derive from your lower spine called peroneal nerve. This nerve is a branch of the sciatic nerve, and the compression or inflammation of these nerves can affect your knees. In fact, compression of the sciatic nerve can trigger symptoms all the way to the end of your leg.

This is known as referred pain, a mechanism where the pain is felt in a region different from the region where the cause of the pain is located. In this case, if the nerve is compressed in the second, third, or fourth lumbar vertebrae, the signals of the sciatic nerve being compressed, will be transmitted by the sensory nerve to the knee, causing pain, numbness, tingling, or weakness in the knee.

It is also frequent for patients with sciatic to develop a Gait pattern, a specific patter of walking, that can end up putting more pressure on the knee by forcing the knee to perform unnatural movements and putting additional pressure on the knee joint. This pattern can over time cause knee pain, even if there is no direct effect of the peroneal nerve in muscles around the knee.

What is Sciatica

Sciatica is very common medical condition that affects your lower back. Approximately 40% of the population will experience once or more during their life. It is more frequent in older population, but it can also be found in rather young patients. Although it can be treated it is common to have recurrent episodes which are very painful and debilitating.

The structures affected by this condition are your spinal discs, nerve roots, joints and soft tissues, such as muscles.

It results form the compression or inflammation of the nerve roots in your lower back, which in most cases translates to pain in the lower back, buttock and tight. However, as the sciatic nerve goes from the lower back to the toes, the effect of compression and inflammation can be felt in the entire leg. Depending on the region of compression, degree

Examples of conditions that can trigger sciatica include:

• Degenerative disc disease: disks between the vertebrae wear down;
• Disc herniation: the inside of the discs between the vertebrae leaks out and compress surrounding nerves;
• Spinal stenosis: the spinal canal gets narrower and pinches the nerves;
• Osteoarthritis;
• Malignancy;
• Trauma to the spine;
• Pregnancy.

Symptoms of Sciatica

The most common Sciatica symptoms are:

• A moderate to severe pain in lower back, hips and down your leg. This pain is many times described as pulsating;
• A feeling of weakness or even numbness in your lower back, hip, leg or feet;
• A pain that worsens with movement, forcing you to stop. Even finding a position to rest is not easy in some cases;
• A feeling of being pinched by needles in your legs and feet.

The pain associated with these symptoms is described in different pains by patients. It is frequent for them to refer to the pain as sharp or jolts of pain, but others describe it as burning or stabbing pain. One common aspect is that most identify the hip and leg pain as more severe when compared to the low back pain.

Some patients suffer episodes of Sciatica during which the pain is constant and even sleeping becomes a problem, while others refer to the pain as waves, with picks and lows.

Most of the time Sciatica only affects one leg at a time, but there are some situations where both legs will be affected simultaneously, depending on where the nerve is being compressed.

If you suspect, you are suffering from Sciatica you should consider visiting your physician for a diagnostic. To better discuss the situation, note down in advance the following aspects:

• Where do you feel pain or discomfort?
• How often does this happen?
• How would you describe the pain?
• How long does the pain lasts?
• What triggers the pain?
• Anything that helps ease the pain?
• Do you spend a lot of time seated?
• Do you do heavy physical activities during your day?

The answer to these questions, together with some exercises and in some cases radiology exams, will help your physician better understand your case and find a solution for it.

Symptoms on your knee pain that point to Sciatica being the cause of the pain

As mentioned before, Sciatica is not the most common cause of knee pain so you should first exclude that the symptoms you have were caused by one of the most common causes, usually associated to knee injuries, degenerative arthritis of the knee joint and repeated stress on the knee. If there is no reason to believe one of the earlier is causing the knee pain, then it is time to look deeper and see if Sciatica is behind your pain.

Some of the symptoms that suggest your knee pain might be caused by Sciatica are the following:

• A feeling of warmth or a sharp pain in the front, side or back of the knee;
• Difficulty to carry the weight of your body on the knee;
• Knee suddenly giving out (no strength);
• No strength when you try to extend your knee.

These symptoms are somehow general so you should be paying attention to symptoms outside the knee. For patients with Sciatica knee, it is common to experience intermittent back pain, hamstring tightness, weakness in the hips or quads and development of bunions on your feet. From the complementary symptoms, the pain in the low back is the most obvious but keep in mind that tis pain is usually much milder than the pain in legs and knees and can be overlooked.

When you have one or more of these conditions, you should consider evaluating if it is the low back problems that are causing you knee problems:

• Your knee pain coexists with a low back pain. The level of severity of the pains might differ but if there is a low back pain it is a strong signal that there might be a relationship, especially if you spend your day seated;
• Tightness on the back of your thighs. There is a group of muscles in the back of your thighs called hamstring muscles. If you try to stretch these muscles and regardless of your attempts the tightness does not disappears, this is a signal that there is lower back nerve causing this issue. This tightness will cause changes into your posture and put extra pressure on the spine and nerves but also directly on the knee, since your knees will need accommodate unnatural movements to compensate the tighten hamstring. If this is a chronic problem, the meniscus cartilage in the knee joint will start to be damaged and the knee will swell;
• Your quadriceps and hips are weak. The quadriceps are one of the most powerful group of muscles in your body, in case you did not suffer a physical injury, if they feel weak and you cannot use them at full strength, there might be the influence of the nerve behind this poor performance. Once again, the poor performance of quadriceps and hips will need to be compensated by the knees increasing the pressure on this joint;
• You have bone spurs on your feet. Low back nerves coordinate the muscles that stabilize the inside and outside of your feet. Once these are affected, you will place your feet differently flattening the arches and putting the big toe joint under a lot of pressure. This is where the bone spurs or bunions will be formed. Over time both your feet and your low back will have poor performance and the knee joint will pay the toll for compensating it leading to knee pain.

How to get rid of my knee pain

If it is confirmed that Sciatica is the cause of your knee pain, it is necessary to eliminate the problem by its root. For this reason, the main focus will be to treat the Sciatica and somehow manage the knee pain while you are doing it. You should obtain a detailed plan from your physician or physiotherapist on how to treat your Sciatica. The better and quicker you can control it, the faster you will see benefits for your knees.

During this process you might consider NSAIDs to cope with inflammatory processes, but you should align with your physician regarding how much and for how long to use these. You should also consider local anesthetics that will allow to sleep properly by suppressing the pain temporarily.

There are some preventive actions you can do at home to speed up the recovery and prevent recurrence:

• Avoid being seated for too long during your day. This increases the chances of low back problems;
• Get to a healthy weight and stay there;
• Stretch or do yoga exercises that relieve low back tension;
• Make use of ice packs and heating pads to relieve inflammation and pain. Do not use these directly nor for more than 20 minutes;
• Wear comfortable shoes.

Be patient and focus on solving your lower back problem, while sparing your knee. Most importantly during this time be careful and avoid situations that can further hurt your low back nerves and your knees.

How to treat Sciatica

If you have already been diagnosed with Sciatica, you should have in hands a plan for how to cope with the disease episodes. These will probably include recommendations for physical therapy, postural correction, and self-care. Most of the cases, Sciatica treatment uses conservative methods without making use of surgery. An acute Sciatica episode can usually be solved in approximately 2 weeks, but you might experience several episodes during a year. Chronic Sciatica, on the other hand is a frequently recurrent situation that will not improve without specialized physical therapy.

Physical therapy will be a crucial part of the treatment plan, especially for patients with chronic Sciatica. These exercises will focus on recovering during an episode but also on how to prevent or minimize future episodes.

Some of the most common exercises to remove pressure form sciatic nerve are:

• Knees to chest;
• Pelvic tilt;
• Lower trunk rotations;
• All fours opposite arm and leg extension

Postural correction will help you maintain a good posture to keep your back, hips, knees, and feet properly aligned. This will ensure that each joint and structure is doing what it has been designed to do and, in this way, not putting extraordinary stress in any of the related structures. It is also crucial to learn how to do some movements in a safe way, like how to safely lift, minimizing the exposure of the low back to stress.

Self-care activities will be the habits you will develop that contribute to recover or avoid Sciatica episodes. These habits focus on maintaining a healthy weight, knowing which exercises to do daily to stretch and relax your lower back and how to strengthen your back muscles.

Both postural correction and self-care habits will strongly contribute to keep you away from future episodes that could damage your lower back but also your knees.

An acute Sciatica episode can usually be solved in approximately 2 weeks, but you might experience several episodes during a year. Chronic Sciatica, on the other hand is a frequently recurrent situation that will not improve without a specialist help.