A Deeper Look at Hip Strength and Knee Pain (Part II)

Last week, in Part I, we looked at shortcomings in the structuralist explanation of how hip weakness causes knee pain.

This week, we get down to brass tacks.

If studies have shown hip strengthening reduces knee pain (and let’s assume for now that many studies have shown this, though I don’t know if that’s necessarily true), one attitude might be:

Who cares why it works? I’ve got bad knee pain. I’ll try anything that works, especially if it’s gone through the crucible of rigorous scientific testing.

So this week we’ll look at that argument, but in an unusual way. The first half of the post will be simple and visual (Cool! Pictures!).

Hey, why not have a little fun? :)

So, in other words, we’re going to start with a:

Now then, if you’re a carpenter, you’re familiar with the image below. Even if you’re not a carpenter, I bet you know what it is:

That’s right. A nut and bolt. There are many, many things in this world joined by nuts and bolts. But what if, at some point, you need to remove that nut? Hmm. How are you going to do that.

Now I know everyone knows what this is:

Praise be to opposable thumbs! Using your fingers, if the nut isn’t screwed on too tightly, you can remove it.

Let’s be charitable and say FINGERS are OKAY for removing nuts from bolts. (Actually, if we’re honest, we’d rank them as short of OKAY. But at least they’re better than nothing.)

“OKAY” isn’t very good though.

What about this instead:

A pair of pliers! That will certainly work fine -- for most nuts tightened to bolts. So let’s say PLIERS are BETTER at removing the nuts. We’re making progress!

But, alas, you’re going to run into that really-tightly-screwed-on nut or that rusting nut or that difficult-to-remove-for-whatever-reason nut. Sweat will break out on your forehead as your trusty pliers succeed only in stripping metal off the fastener’s edges.

Hmm. What works better than pliers?

How about these:

Yup. Socket wrenches. The mouth of the wrench fits snugly over the six-sided nut. It’s the perfect tool for the job. This is what the socket wrench was designed to do, tighten and remove metal hexagonal-sided nuts.

That doesn’t mean it will always work. There are times it will fail. Still, it does the best job.

So let’s say SOCKET WRENCHES are BEST at removing nuts from bolts.

Okay, we’ve reached the end of the picture book session. :)

What does all this have to do with rehabilitating bad knees by strengthening your hips? Well, actually it has more to do with the Big Picture: finding the best way to rehab your knees.

Imagine a one-year study broken into the following groups of chronic knee pain sufferers:
(1) 100 people who do nothing but live their ordinary, rather sedentary lives (our control group).
(2) 100 people who go through a program of hip strengthening.
(3) 100 people who go through a program of quad strengthening.
(4) 100 people who go through a program of high-repetition, low-load activity that only gradually increases in intensity (basically, the kind of program that saved my knees).

Say that in the original 100 people, the knees of 5 spontaneously get better after one year. Not many, but a few. So that’s our benchmark.

Now the 100 people who go through hip strengthening will potentially get several benefits. They should gain from getting in at least some activity (by doing exercises related to hip strengthening, which is certainly better than sitting around on the couch). They may benefit too from the placebo effect -- the mere fact that a physical therapist is working with them will encourage some to think they’re getting better. (Note: One problem with such an experiment is that it can never be truly blind for participating subjects; it’s impossible to disguise who’s getting the physical therapy attention and who’s not).

Still, I would guess that many will not get better.

Say in the hip strengthening group, the knees of 20 subjects appear to improve. If you just compare hip strengthening with doing nothing, then you have to conclude: strengthening the hips is a winner!

But what if we look at the quad-strengthening group -- there have been studies showing that quad strengthening helps bad knees. Strong quads arguably have a more direct effect on the joints and can help cushion them from harmful impacts. While the quad exercises will probably be too strenuous for some knees, others will tolerate them fine.

Say in this quad strengthening group, the knees of 35 subjects improve. Once again, if you just compare strengthening the quads to doing nothing, bulking up the quads wins the day!

But what if, in the last 100 people, who are trying to heal the joint itself, there is even more success? Say in this group, the knees of 80 subjects improve. Now where are you?

Well, the analysis would be something like this:

HIP STRENGTHENING is OKAY for beating knee pain.
QUAD STRENGTHENING is BETTER for beating knee pain.
JOINT STRENGTHENING is BEST for beating knee pain.

Naturally, this is what I expect such a study would show. It’s a shame no one has done one, so we don’t know.

If this is the case, the fact that quad strengthening shows some success, as does hip strengthening, tends to muddy the waters. They work okay for treating patellofemoral pain syndrome, but not great. In fact, where we’re at today in terms of standard treatments for managing PFPS can be summed up like this: Nothing works very well, but a number of things work better than nothing. (If you doubt this point, just review the literature about this condition -- I have -- and see how often medical professionals complain that PFPS is a mysterious problem that’s hard to solve. That's the best indictment I know of the standard treatments.)

But the fact they sometimes work means people keep using and trying to modify them. Unfortunately, no one seems prepared to make the radical (yet simple) leap: Why not just try joint strengthening? It’s an injured knee. Maybe it just needs to be healed, just as other injured structures do?

Closing note: I can imagine a structuralist type fuming about the statements “hip strengthening is okay” and “quad strengthening is better” with the remark, “Well, it depends on what’s causing the knee pain in the first place! Maybe hip strengthening is great for weak hips and quad strengthening the best approach for problems related to weak quads!”

But let’s get real for a moment. The fact is, right now, the mass of patellofemoral pain syndrome sufferers are basically like those in the hip strength study I began this series by looking at: They suffer “diffuse peripatellar and retropatellar pain of an insidious onset” and there’s no clear sense of what’s going on. Six different medical specialists may say six different things. A LOT of confusion surrounds PFPS. So in my hypothetical study above, I’m just assuming we round up a lot of PFPS patients with diffuse knee pain that appears to have an unclear origin -- because that’s what the real world looks like.

Maybe someday, in another 10 or 20 years, we’ll be at the point where we can focus on comparing hip strengthening to knee joint strengthening for specific subsets of patients, who fit certain criteria that leads some to believe their hip weakness is the essential contributor to their knee pain. But even so, I’m betting that, if put side by side, joint strengthening would prove superior as a treatment. Hopefully, someday we’ll see.