So you've come to see your Physiotherapist about your knee pain. There was no traumatic mechanism as such that you can recall, but for no particular reason it has been annoying you whilst walking, going up stairs, bending and maybe even whilst sitting doing nothing! You and your Physiotherapist discuss together a thorough history, aggravating and easing factors and specific questions are asked in an attempt to understand the behaviour of pain.
The Physiotherapist assesses your knee joint measuring range and strength, checking knee special tests and gathering functional objective baselines, monitoring pain response. Your Physiotherapist explains to you that the knee joint itself is looking very strong and healthy. Furthermore, it is explained that it’s important to screen further up the chain, check how well your low back is moving and assess if your low back is contributing to your knee pain. You find yourself bending forwards, backwards and side to side and perhaps, at this stage you might be thinking to yourself why am I moving my back around for my knee pain?
The source of your pain
According to an EXPOSS study in September 2019 investigating spinal source of pain for extremity pain, 43.5% of cases were found to be spinal source of pain (neck, thoracic and low back) and this increased to 83.3% when pain location is in between joints. To break it down further, spinal source of pain was responsible for 71% of hip, 25% of knee and 47% of shoulder cases.
Locating the cause of the problem is of clinical importance and key when managing an injury or pain. It is essential to zoom out and screen globally as well as locally. If by moving your low back we can influence your knee pain whether better or worse, it provides good evidence that perhaps your spine could well be contributing to your knee pain. It is simply a process of ruling in and ruling out. And with great reassurance this does not mean your spine is injured, it is just playing a part in how your knee feels.
How and why?
Pain from a structure that is felt in a different location to where the pain is coming from is known as referred pain. Radicular pain is caused by irritation at the nerve root and Radiculopathy is when the nerve root is irritated and accompanied with weakness, numbness and altered sensation. Unassumingly, if a structure in the spine is annoyed it could well be referring away from the spine and causing pain in the extremity such as the knee, depending which level of the spine is annoyed.
If the next time you are with your physiotherapist and you find yourself moving other parts of the body other than the site you came in for, it should hopefully make a little more sense.
Rosedale R, Rastogi R, Kidd J, Lynch G, Supp G, Robbins SM. A study exploring the prevalence of Extremity Pain of Spinal Source (EXPOSS) [published online ahead of print, 2019 Sep 2]. J Man Manip Ther. 2019;1‐9. doi:10.1080/10669817.2019.1661706