When it comes to knee pain, we often tend to think first of the front and sides. But pain that comes from the back of the knee is probably every bit as common.
It would be helpful if there was a single likely reason for this! But in fact the causes of back-of-knee pain can be very diverse. You could experience it as a sudden pain or a gradual ache. There may be swelling and inflammation – or none at all. You might find it difficult to fully extend your leg.
In other words we need to do some narrowing down to find out what’s going on. One useful starting point is to think in terms of problems inside or outside the knee joint: in medical-speak, intra- or extra-articular causes. Let’s have a look at the most common ones.
INSIDE THE JOINT
A cartilage tear – if you fall or twist your knee during exercise, it’s possible to damage the cartilage in your knee joint. Two common areas to injure are the meniscus (the pad that provides cushioning in your knee) and the chondral (which provides a smooth covering for bones). A tear to either of these can be felt at the back of the knee. Wear and tear, perhaps from long distance running, can also cause cartilage damage.
Osteoarthritis – arthritis is a degenerative condition that causes your protective cartilage to wear away. Age is a factor (particularly from 50+), but it can happen after injury too. Quite often this leads to a flexion contracture, where the knee becomes difficult to straighten or extend. When you try to walk, it can put strain on the posterior (rear) capsule in your knee, causing pain there.
- Find out more about early signs of osteoarthritis in the knees.
A knee sprain – a fall or sporting injury can also cause one of the ligaments in your knee to tear. This can result in instability, swelling and pain – sometimes at the back of the knee. One possible culprit is the Posterior Cruciate Ligament (PCL), which runs in a cross-shape at the rear of your joint.
- Find out more about your PCL in our recent blog.
Hyperextension – this is what happens if your knee joint bends too far backwards, usually as a result of sporting damage when the knee over-straightens. Hyperextension often causes instability and at least some pain or discomfort towards the back of the knee.
OUTSIDE THE JOINT
Baker’s Cyst – this is a very common reason for rear knee pain. Also known as a popliteal cyst, it’s what happens when fluid leaks out of the joint, usually due to arthritis or an injury, and collects in a lump. Larger cysts can exert pressure on muscles and nerves. Doctors tend to think of these cysts as a window into the knee – they often indicate that something else is going on inside.
A hamstring issue – most of us experience a hamstring twinge at some point; perhaps after an ill-advised lunge in football or a sudden sharp pain on sprinting. It’s possible to develop tendonitis in your hamstring too, where tiny tears cause inflammation and discomfort. Either way, even though the hamstring sits well above the knee joint, it often causes pain behind it.
A calf strain – just as upper leg muscles like the hamstring can cause problems in the knee, so can lower leg tissues. Chiefly this means the soleus or the gastrocnemius (calf) muscles. When these become fatigued, strained or torn, they can be felt as posterior knee pain. Tendonitis of the gastrocnemius is another potential issue here.
WHAT HAPPENS NEXT?
Since there are so many possibilities, the key thing is to be thorough. Here at the clinic we kick off by asking patients about their back-of-knee history – when did you first notice the problem? What were you doing at the time? Does it get worse again with certain activities? What does the pain actually feel like? We’ll follow that with an examination to feel for things like a cyst or flexing problems. We’ll also organise an MRI scan. Sometimes this will highlight the problem immediately – something like a tear or a hamstring issue; but surprisingly often with back-of-knee pain, the scan will look ‘clear’. That’s usually reassuring, since it indicates a less intrusive problem. So at this point we’d also look at your activities and sporting techniques and whether they might be causing the issue. By doing all of these things we’ll build up a full picture of your knee and the best way to fix it. As you’ve seen, back-of-knee pain can be a slippery customer. But with a little bit of detective work, we’ll get to the bottom of it.
Are you experiencing painful symptoms behind your knee? If so, we’re here to help if you need us. Drop the team a line on 01962 826107 or fill in a quick online form – we’ll be back in touch with an appointment as soon as possible.