As Physiotherapists, we deal with Sciatica and knee pain on a daily basis. Most times we see Sciatica OR knee pain, but can one cause the other?
The short answer is YES, Sciatica and knee pain can be caused by the same issue.
There are a few tell-tale signs that the Sciatica is referring pain into your knee, and other indicators that you might have two separate injuries.
We’ll detail the two conditions and what to look for to figure out if your Sciatica and knee pain are linked.
What does Sciatica feel like?
Sciatica is an irritation of the Sciatic nerve that runs from the buttock down the back of the leg into the foot.
It’s a very thick nerve that gradually separates into its branches as it descends the leg.
Like most nerves in the body, it supplies electrical signals to activate muscles as well as sending sensation information back to the brain.
[Side note: there are some nerves in the body that exclusively activate muscles without providing sensation information, and vice versa.]
When it’s irritated, it causes abnormal sensations like pain and tightness to be felt.
These sensations will feel like they’re in a part of the leg that is supplied by the nerve.
That same disruption to nerve signals works both ways, affecting the signals sent to activate the muscles.
This can change the way the muscles activate and how the leg moves.
Can Sciatica cause knee pain?
Any nerve irritation is always felt further down the chain – the Sciatic nerve will never cause symptoms higher than the location of the issue.
The most common location of irritation of the Sciatic nerve is in the buttock or in the lower back.
These locations frequently lead to pain around the hamstrings, described as tightness, a radiating ache or a line of pain.
This pain in the back of the thigh can radiate up into the buttock as well as radiating down to the back of the knee and the calf, depending on the severity of the nerve irritation.
Sciatica can directly cause pain in the knee but only at the back of the knee – the nerve doesn’t supply the front of the knee so it’ll never send pain there.
But that’s where it gets more complicated…
Once the nerve is affected, the muscle function is compromised and the leg will move differently.
The abnormal loading patterns can then cause separate pain in joints and tendons in addition to the nerve pain.
Indicators that your Sciatica and knee pain are linked
The clearest indicators that your Sciatica and knee pain are from the same source are:
- Knee pain only at the back of your knee
- Knee pain that moves up into your hamstrings or down into your calf
- No other knee symptoms or signs, like front of knee pain or knee swelling
Indicators that your Sciatica and knee pain are from two different injuries
These signs and symptoms will confirm that you probably have Sciatica and knee pain from a separate knee injury:
- Knee swelling
- Pain that covers from AND back of the knee
- Pain that spreads from the back of the knee to the front (rather than spreading up or down the back of the thigh)
- Sharp knee pain
So, can Sciatica cause knee pain?
Sciatica can cause nerve pain at the back of the knee, but it can also cause altered movement patterns which can generate a separate knee injury.
Keep an eye out for indicators of a separate knee injury, like swelling or pain at the front of the knee, as these can develop over time and emerge weeks or months after the start of the Sciatica episode.