What’s Behind Posterior Knee Pain?

By Jonathan Bell

Everyone, at times, finds it difficult.

Did you start reading this because you've previously found diagnosing posterior knee pain difficult? Well guess what? In spite of being a knee surgeon for nearly 30 years, I still think it is one of the most challenging symptoms to unpack in the knee. 

However, you’re in luck. Because I like an easy life and don’t like being proved wrong, I've developed a system for diagnosing posterior knee pain and I'm happy to share it with you.

Why is it such a challenge?  I think it's in part because possibly 80% of posterior knee pains will be from something simple like a Baker's cyst or referred spinal pain. The remaining cases could be any of about 20 other diagnoses. Many are relatively rare. Some are important not to miss. If you are interested in seeing how I do it, read on.

Hoping to diagnose the cause of posterior knee pain by just getting an MRI will frequently lead to misdiagnosis or no diagnosis at all. Only yesterday I saw a patient who for the last eight months has seen multiple specialists and undergone multiple MRI scans, including a contrast scan, but still didn't have a diagnosis. Yet the diagnosis was very clear. It was easily diagnosed by examining the patient! With posterior knee pain the examination element of the assessment is especially critical to getting it right.

Some prefer not to use a structuralist approach. My view is you've got to start somewhere. I think it can be quite helpful to take that approach, at least to start with. I fully understand that centrally driven causes can feature in any patient with knee pain; I don't seek to dismiss that. For that same reason I won't be covering systemic conditions such as collagen diseases or inflammatory arthropathy. This is not the place to discuss polytrauma, bleeding or infection and whilst children will have some of the same diagnoses, this is also not specifically intended for assessing children.

By all means copy this and use it in your practice and please leave comments, especially if you think there's anything that you could add to improve upon it. As always, knowledge should be an evolution.

Have a glance through the decision tree if you haven't already, then I'm going to explain some of the more nuanced elements that might help you apply it.