My knees always blighted me in early life, constantly referred to by my siblings as my ‘knobbles’ and always pointing in funny directions. However, as a runner they have served me well, have got me through many traffic jams using clutch control and only complained mildly despite the awkward positions I put them in during yoga sessions. As a physio too, I feel a swelling of pride when other physios praise them for showing all the details they want to see – a palpable joint-line, clear tendons and ligaments, and of course a very knobbly kneecap!
Despite the knee being ‘just’ a hinge joint, at the mercy of the huge muscles of the thigh and calf, it is still amazingly complex, and there are a huge number of intricate structures that work silently in the background along with the obvious big movers.
Here’s an introduction to just a few of my favourites that may help you appreciate the wonder of the inner knee!
Bursae, Bursitis and Housemaids
The bursae are fluid-filled sacs which act as buffers for all the bony bits of your knees to move in harmony without causing friction on each other. They also, crucially, absorb shock and literally create padding for your bones when kneeling, crawling and bashing them on furniture. You’d never know they were there until they went wrong, but there are ten of them (arguably 14) in and around your knee alone.
Sounds logical huh? But don’t take these bouncy little sacks for granted, because when they’re irritated it can cause a range of symptoms that are often hard to settle down. Swelling is a classic sign, heat, pain and restricted movements can all follow on. The area can throb and become really sore – in hip bursitis, for example, sufferer are unable to sleep or even rest for short periods of time on the affected side, but also can’t walk long distances either for causing irritation.
The good news is that these symptoms are also signs of arthritis, which is much harder to ‘solve’, so it’s always worth getting a proper assessment if you are experiencing these symptoms, as it might be more manageable than you think. Also, X-Rays can often show up joint degeneration which can be alarming, but in truth is not actually the source of your pain.
For example, a recent study has shown that even from our 20s and 30s our spinal bones can show signs of degeneration, but in the study all of the subjects were non-symptomatic – i.e. they had no pain or restriction of function. Arthritis can feel like an ‘old-age sentence’ but it might actually not be the problem. Another study has shown that over 86% of subjects over 50 had lesions within their knee joints, but were pain free. So if you are getting a scan, ask questions and keep an open mind wherever possible – the ‘results’ may not be the answer to your problem.
This rather alarming bump (above) was caused by simply kneeling a lot and unsurprisingly is known as ‘Housemaid’s Knee’. Common with plumbers and childcarers, I also know someone who developed this after their cat was ill and he spent many hours clearing up the mess on the carpets..!
Popliteus and Articularis Genus: Unsung Heroes of the Knee?
These little muscles are truly genius, and like the bursae do jobs you didn’t realise need doing. Yet they are crucial to knee stability and function, and you’ll know about it if they are under-performing.
Popliteus, aside from having a cute name, is crucial for getting going. Most of us lock out our knees when standing, and this small diagonal muscle wraps around the back of your knee, both stabilising it in standing and initiating the un-locking of the joint and getting started. It flexes (bends) the knee and rotates the shin bone (tibia) relative to the thigh bone (femur). Can you imagine doing this without the Popliteus? Having to manually push your knee forward to even begin moving? It can get tight or overworked if your hamstrings aren’t properly braking and controlling the swing-forward of your lower leg while walking. This can result in posterior knee pain, which can come on after a few miles of running, or at the end of a day’s walking about.
The Articularis Genus is another little gem, and is responsible for moving your kneecap up just that last little bit to get it out of the way when you fully straighten your leg. It really is quite small and lies underneath your quadrucep muscles on the front of your thigh. I have seen cases where patients can’t fully extend their knee because this muscle is dysfunctional – again, try to imagine never being able to straighten your leg! Never standing straight, buckling when walking, the associated swelling of the joint tissues (and bursa!) being pinched by the sluggish kneecap (patella). It can all be because this poor little muscle needs a bit of R and R.
As an aside, trauma to these muscles could be seen (in my opinion) as Whiplash of the Knee. Just like the neck, the knee can experience trauma to soft tissues from rapid acceleration and deceleration (the clinical definition of whiplash) through fairly common activities such as twisting while skiing / snowboarding or jolts from kicking something unexpectedly hard. The muscles can spasm while performing their major function of protecting the joint against sudden excessive movement, especially these smaller ones which have a less obvious but no less important function than the bigger quads and hamstrings. Gross movements return after the initial shock, but have a feel around and there’s usually some rock solid tissue that isn’t able to perform its finer functions.
This sort of pain or restriction can literally last for years and put strain on other structures. It can alter motor patterns set by the brain and cause compensatory mechanisms in feet or hips over time. It can also cause these muscles to malfunction because their activation patterns have been disrupted. I often see cases of ‘Frightened Knee’ (again, my term, not a clinical definition!) where muscles can protectively spasm at seemingly random times, stemming from an earlier sudden trauma that had seemingly resolved. So if you’ve had a similar injury and still get niggles it’s worth looking again as these things can be relatively easily solved.
So if you’ve got pain in your knees, don’t let it suffer and get worse – appreciate their virtues and embrace your new knowledge of the knobbles!