Trying to understand the Hip / Knee connection...

[whilom]

So, for nigh on thirty years every Spring I've gone through the same process, and I'd really like to understand better what drives this process! It's not an injury type situation, more just a profound curiosity about why my body stresses and then heals this way!

The context:

• I have since age 13 cycled on average close to 10km/day (for two of my nearly four decades of cycling the average was closer to 20km/day)
• When I was a teenager I could sit in a lotus easily but since I wasn't smart enough to do so once a month through my twenties, by 30 I could not get even close to externally rotating my hips enough to sit in a lotus
• My preferred vacation is multi-day hiking treks of 100-200km, and getting to and from these hikes on multi-day motorcycle rides
• I don't hike November to May, but while I cycle less in winter, I never cycle less than 30km in a week minus about ten "snow" days a year
• My body is generally fit enough that my first hike in May is around 20km. This certainly tires my legs and hips, but only enough to make them stiff the next day, not sore like serious training does. My legs strengthen up, and usually in July I'm good to go for a multi-day trek without any soreness or stiffness

The MYSTERY:

• Late in my first hike of the year, and sometimes the second and third hikes if I really challenge myself, I start to experience pain under the bottom interior quadrant of one or the other of my kneecaps only when I'm *descending* for more than a few strides. Usually the right kneecap, but it has sometimes been the left
• Somewhere along the line I figured out that doing an exterior hip stretch, usually using a log like we might use a counter or bed for that stretch, instantly relieves the knee pain and returns the function of my knee to normal
• I also noticed that fully engaging my quads when descending slows down the progression / onset of the knee pain
• After stretching my hip, the knee pain will eventually return, over shorter and shorter intervals till by the end of the hike if I have to descend I might stop to stretch my hips (I do both even though only one knee ever hurts) I might stretch every 200m
• The knee pain is occasionally present the next day when descending stairs, unless I've done some external hip stretches first, which I usually do for three days after my first long hike
• I stretch my quads, glutes, calves, pretty much daily all the time, as they just seem to appreciate it, but the hip "stretches" which don't really feel much like stretches since there seem to only be tendons and ligaments involved, I stop doing once they no longer register any stiffness

So what's the deal? What does the exterior of my hip have to do with the bottom inside corner of my knee? Why does descent only induce this? How can exaggerated engagement of my quads affect this? I suppose the only real functional questions would be:

• Would a more rigorous program of external hip rotation stretches prevent this from happening each year?
• Are there other stretches I could do to keep the knee/quad/hip system in better shape?
• Are there other benefits or reasons why I should seriously consider investing time in improving my external hip flexibility? I wouldn't mind being able to sit in a lotus again, but... is there a need?

This might all seem a bit frivolous, since there's no injury or ongoing issue, but just the regularity of confronting this and being left with a gaping curiosity *every* Spring has me coming to a group of experts like you looking for some understanding. It's gotta be 25 years I've been wondering about this, I'd kind of like to not wonder about it 25 more!

Most sincere thanks for your attention!

Best,

Whilom

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[physiobob]

Hi Whilom and thanks for your interesting post. It seems an annoying but very normal situation and you have in some ways identified the issue along the way.

Think of the knee as a hinge of a door in that when everything is in balance the hinges are no under undue stress. However hang on the door and you upset, bend or even break the hinges. The knee only moves if the ankle and the hips bend (i.e. it is the open/close pivot between them) so if there is suboptimal movement or control in either of those two joint then the knee will suffer a a result. The patella itself is a piece of bone essentially embedded in the tendinous part at the end of the quads muscles which then anchors to the tibia so the direction of pull of those quads muscles on the patella will dictate how the load is spread as it located itself into the patella groove at the end of the femur. If the quads are a little tight at the beginning of your activity then that might cause the patella to locate itself a little high in the groove and so load the patella unevenly. A quick stretch can allow a slight lowering of the patella during that location and shift the load elsewhere. Now this is why a quick stretch can move discomfort away initially. It is likely however though that over the years you have begun to have a little uneven wear on the patella so it does catch up with you eventually. Contracting the quads or focusing more on that control as you land on the leg will also have the effect of giving a more balanced load the the patella on landing.

The different between upstairs/climbing up and downstairs/going downhill is that when you go up you plant the foot in a bigger bend of the knee before applying the load to the patella. It is in a much more secure and appropriate position in the patella groove before that load is applied and quads are working concentrically (shortening) to support the weight. This deeper bend and nicely located patella is also relevant when cycling and is a different mechanic therefore to descending when hiking. When walking down hill the foot is free (as is the patella floating above the groove) and the load is transferred immediately to the knee cap on landing. The quads are working a little eccentrically (lengthening with control) as the knee cap tries to find a nice fit in the groove. As a result more can go wrong and this is why we most often find a difference in symptoms between going up/down stairs.

Over all consider that the control of the load to the knee cap when going down hill therefore replies on the control about the ankle (eccentric calf muscle work) and the control of the hips, so quads and gluteals (but in essence everything above the knee joint). Imbalances even in strong muscles will cause a shift in the directional pull on the knee cap and can lead to degradation as a result. I would focus on working on the control of the movement. Perhaps box stepping at various heights (start small) and over time get taller boxes to work the control of the leg in both the up and the down directions. Have a friend watch to see if your knee rolls in excessively as you step down as that might indicate some gluteal control exercises are in order. In terms of the reduction in hip mobility and its effect on the entire lower limb movement (and low back movement too) it is of primary importance! It is one of those first things to go as we get older and is one that when restored has all sorts of positive benefits to the movement chains. I lost a lot of mine over time with too much cycling and weight training (and just sitting more as we leave our school years behind) and lockdown was a gift in that I was able to take up yoga again for the first time in 2 decades. My hips have opened up again and I have a stronger and renewed cause/effect understanding about the importance of that maintenance.

Let me know your thoughts as this is really a huge discussion that could be talked bout for days. But the essentials are understanding the difference in the loading of the patella between up and down hill movement and to consider that discomfort in the knee cap is a result of that suboptimal loading. Fix that control and the knee cap symptoms will diminish.

regards

PB

[whilom]

*Blissful understanding!* Thank you so much for your detailed explanation, as I often work as a handy person, the door hinge analogy is perfect: loose hinge screws allowing rotation of the hinge out of plumb are the cause of tremendous stress and wear on the hinge pin itself! Basically what I understand from your explanation is that both my hip (as an attachment point for my quads) and my ankle/calves act to stabilise my patella where it should be to transfer load around my knee, and when my quads or likely the external section of my quads start complaining from hiking stress and disengaging somewhat, pain can ensue. This also explains why a bit of a restorative stretch of my hip and being more intentional about engaging my quads helps relieve the pain by allowing for better alignment of my patella.

I will indeed do some focused box stepping work, as, in my mind hitherto unrelatedly, I recently moved to a new apartment with a lovely attic bedroom up some steep and curved stairs, and I have found that I feel slightly unstable coming down them unless, again, I very intentionally engage my quads. Without doing so I can see my knees deviate slightly internally. I hadn't connected the two because on stairs I tend to experience the sense of instability in my ankles not my knees. My knees have apparently been happy to do stairs, even normal ones, without much (conscious) quad involvement forever.

Can I ask, since I cycle with cleats, is it possible that pulling up against my pedals, which I gather is accomplished mostly with my quads, disproportionately strengthens the interior parts of my quads and may leave the exterior proportionately weaker? Would such an imbalance factor into my situation?

I can't tell you how grateful I am for this understanding, it's like the most satisfying deep drink of yummy thirst quenching goodness after a long and hot ride, but on a bigger scale! Understanding *how* things work mechanically is almost as satisfying to me as just the reality that they do work!

Best,

Whilom

[physiobob]

Cleats and pulling up can cause an issue if it is excessive and is not balanced with the handover to the gluteals. Think of the movement as one of momentum, like beating an egg, as you are trying to create an elliptical motion to spin. Bike setup also comes into play with this and that is a whole different story. It is worth going to an expert bike shop who specialise in the setup to see if there are any tweaks needed there.

[whilom]

Oh, I like your analogies, the egg beating analogy is much better than the log-rolling analogy I was working with. Yes, I'm vaguely aware that there's a big difference between just up-and-down pedaling and round-and-round pedaling, I will pay more attention but in the past I think I've noticed that I'm much better across the top (smoothly going from up to down) than I am across the bottom, going from down to up, that almost seems jerky sometimes. If anyone has any advice in terms of exercises to help make sure I'm biking around rather than up-and-down it would be much appreciated.

In terms of geometry, the bike was custom built specifically to my measurements, the frame builders had a sort of adjustable bike they set me up on and adjusted away until they were completely satisfied. Can't speak to their methods, but Jupiter has been a completely comfortable ride from day one (June 23rd 1999) and I haven't changed the geometry a smidgen since then. I once refused to buy a set of new cranks because they were 2mm longer than my original ones!