Preventing meniscus tears (a knee injury)

[Frank Silbermann]

Three years ago I suffered a small meniscus tear in my left knee, and the pain increased over the weeks until I was on crutches. However, the MRI showed that the torn parts were not separated, and the tear was in the outer third where there is still some blood circulation, so the doctor thought if I just rest it and do physical therapy for a few months and it might heal itself. It improved 90% (enough to slowly get back into tennis), and continued further improving (albeit more slowly) as I continued doing the exercises on my own.

I asked my orthopedist what motion causes a torn meniscus. He said it was from twisting the lower leg while the knee is bent. It seems to me that this is most likely to happen if one pivots sharply without un-weighting. The body turns, but the outside foot remains in place. The exercises I do stretch the hip and ankle so they can absorb more of the motion, and strengthen the knee tendons and ligaments so the knee can better resist the torque.

It has long been known that people tend to get more knee injuries from playing on hard courts than from playing on clay; I suspect it's not so much the relative softness of clay so much as the reduced traction that makes it easier for the knee to drag the foot around with it when pivoting sloppily.

Recently, I again had some twinges behind the knee, which is how the initial bout started. I had been wearing shoes I had never worn before for tennis, which had those little pencil-eraser shaped nubs on the bottom. I wondered whether those might have more traction than my worn old shoes. So, aside from doing my exercises more consistently and avoiding tennis for a few days, I bought a tube of Shoe Goo (liquid rubber) and filled in the spaces between the nubs under the front part of the shoes to reduce the traction. I also did that with my other pairs of tennis shoes.

Since then, my knees have felt fine. Has anyone else considered selecting or modifying shoes for reduced traction as a way of preventing knee strains? Theoretically this could slow me down a bit, but at age 55 I don't expect I'll be accelerating or stopping with enough force that I'll miss the lost traction -- and even so it's probably a reasonable compromise (analogous to the use of lower-performing soft strings and flexible frames to prevent tennis elbow).

Comments?

 

[newton296]

I would say that its a fair compromise, the point is to play longer, so just do what you gotta do to stay healthy.

I have found that as far as shoe traction, the harder the sole of the shoe the less traction you get. also the harder the sole the longer it last. so in that spirit , I tend to buy the shoes with a 6 month outsole guarantees and they end up being pretty low traction. I do that to protect my ankles and knees. don't want the shoe locking up suddenly, I would rather slide a little.

anyway, good luck with you knee! I had some tendonitis and my dr told me to try some biking to get it better. just make sure you have the seat and pedals properly aligned before you get too biking alot or you can make your knee worse.

 

[Ramon]

If it comes from the lower leg twisting, do you think it might be from over-pronating? That's when your ankle twists inward and your forefoot twists outward while you run. That's fairly common and can possibly be addressed with motion control shoes and orthotic insoles.

 

[Frank Silbermann]

If it comes from the lower leg twisting, do you think it might be from over-pronating? That's when your ankle twists inward and your forefoot twists outward while you run. That's fairly common and can possibly be addressed with motion control shoes and orthotic insoles.

That's a very minor degree of twisting, and would be easily absorbed by the hip. It's nothing like the violent twisting that occurs when you pivot 90 degrees or even 180s degrees to change directions while reversing your body's momentum.

Of course, if your arches give and your feet flop around the court, then you're not likely to be on the balls of your feed when you pivot; your heel will be probably be down. If that happens, the part of the shoe is going to have to slide a great deal during the pivot, so I suppose it is possible for over-pronation of the foot to contribute. But it's not obvious to me that this would be the problem, nor that artificially holding up the arch would help. Again, it's not the slight rotation of the leg or foot while running that injures the knee, but rather the more violent wrentching that occurs when you forcefully change directions, especially if you don't pick your feet off the ground to reposition them as you turn.

 

[Clintspin]

Do you hit a one-hand backhand or two? If so, are you right-handed?

 

[Frank Silbermann]

Do you hit a one-hand backhand or two? If so, are you right-handed?

Twenty-eight years ago I learned I could never hit a two-handed backhand, lest my lower back seize up, so instead I hit left- and right-handed one-handed forehands. I hit one-handed backhands before that, but I found that the effective strike zone for aggressive play was very narrow.)

 

[ttbrowne]

Wish I'd read this before. I hurt my knee (meniscus) about two months ago. Getting the finals diagnosis Monday. It will not heal on it's own. I can't run at all. I can walk but there is pain. I DID get a new pair of shoes a week before I hurt it! I changed brands so it's starting to fall into place. Some university needs to do a study.

 

[ollinger]

I had the chance the last 5 days to discuss this with some of the top experts in the field -- my wife got home yesterday from Hospital for Special Surgery at Cornell Med School, had a partial knee replacement. They were not so keen on wearing something more slippery, felt it might increase risk. One told me they see alot of meniscus injuries that follow people simply slipping on ice, without any apparent twisting.

 

[charliefedererer]

Three years ago I suffered a small meniscus tear in my left knee, and the pain increased over the weeks until I was on crutches. However, the MRI showed that the torn parts were not separated, and the tear was in the outer third where there is still some blood circulation, so the doctor thought if I just rest it and do physical therapy for a few months and it might heal itself. It improved 90% (enough to slowly get back into tennis), and continued further improving (albeit more slowly) as I continued doing the exercises on my own.

I asked my orthopedist what motion causes a torn meniscus. He said it was from twisting the lower leg while the knee is bent. It seems to me that this is most likely to happen if one pivots sharply without un-weighting. The body turns, but the outside foot remains in place. The exercises I do stretch the hip and ankle so they can absorb more of the motion, and strengthen the knee tendons and ligaments so the knee can better resist the torque.

It has long been known that people tend to get more knee injuries from playing on hard courts than from playing on clay; I suspect it's not so much the relative softness of clay so much as the reduced traction that makes it easier for the knee to drag the foot around with it when pivoting sloppily.

Recently, I again had some twinges behind the knee, which is how the initial bout started. I had been wearing shoes I had never worn before for tennis, which had those little pencil-eraser shaped nubs on the bottom. I wondered whether those might have more traction than my worn old shoes. So, aside from doing my exercises more consistently and avoiding tennis for a few days, I bought a tube of Shoe Goo (liquid rubber) and filled in the spaces between the nubs under the front part of the shoes to reduce the traction. I also did that with my other pairs of tennis shoes.

Since then, my knees have felt fine. Has anyone else considered selecting or modifying shoes for reduced traction as a way of preventing knee strains? Theoretically this could slow me down a bit, but at age 55 I don't expect I'll be accelerating or stopping with enough force that I'll miss the lost traction -- and even so it's probably a reasonable compromise (analogous to the use of lower-performing soft strings and flexible frames to prevent tennis elbow).

Comments?

Great theory.

Good to see see someone thinking outside the box.

But my experience with shoe goo is that it is very soft. It abrades down to the tennis shoe in one session. So there is a varying effect during play, making it difficult to anticipate the actual effects.

Another problem with shoe goo is that because it is soft, it has a high adhesion coefficient. In general soft rubber has a better grip than hard rubber. Basketball shoe outsoles are very soft for great adhesion on slick polyurathane treated wood basketball courts, and would give great stopping power on hard courts, but of course are so soft that they wear out way to quickly.
So perhaps you might be better off with a really hard rubber, plastic or teflon outsole to test your theory.

But if I was the orthopedic surgeon in the area where slick tennis shoes were being tested, I would be prepared for an increase in injuries from falls while the experiments continued.


Anyway, thanks for the interesting idea.

 

[Frank Silbermann]

I had the chance the last 5 days to discuss this with some of the top experts in the field -- my wife got home yesterday from Hospital for Special Surgery at Cornell Med School, had a partial knee replacement. They were not so keen on wearing something more slippery, felt it might increase risk. One told me they see alot of meniscus injuries that follow people simply slipping on ice, without any apparent twisting.

Yes, well, an uncontrolled fall is likely to do any number of bad things to you knees. But I'd hardly compare a sudden slip on ice to having shoes with a little less traction. After all, we don't see people's feet suddenly sliding out from under them while playing on clay.

... But my experience with shoe goo is that it is very soft. It abrades down to the tennis shoe in one session. So there is a varying effect during play, making it difficult to anticipate the actual effects.

Another problem with shoe goo is that because it is soft, it has a high adhesion coefficient. In general soft rubber has a better grip than hard rubber. Basketball shoe outsoles are very soft for great adhesion on slick polyurathane treated wood basketball courts, and would give great stopping power on hard courts, but of course are so soft that they wear out way to quickly.
So perhaps you might be better off with a really hard rubber, plastic or teflon outsole to test your theory.
...

I agree that it would be better to use a harder rubber. But I'm not comparing slick soft rubber to slick hard rubber so much as shoes with deep tread versus shoes with shallow tread. As Charlie Federer points out, Shoe Goo rubs down quickly -- except between the treads. The effect, if there is any, is subtle -- it mostly just makes the treads shallower.

In fact, the point you raise about rubber hardness made me wonder about the mechanism of tread -- on sneakers as well as on tires. By channeling water, tread makes it harder for tires to hydroplane on puddles, but does it have any effect on dry surfaces? I know that drag racers use slick tires; is that to maximize surface area, or is that because the rubber on those specialized tires is too soft to stay together if tread were cut into them? Or, does tread help channel the road dust as well (drag strips being washed clean)?

One way that tread might improve traction (with rubber that is stiff enough to hold the cuts without tearing apart) is by providing a small amount of lateral "give" -- which makes it more likely that static friction will be maintained. (Static friction is considerably stronger than dynamic friction; the static friction of hard rubber will be stronger than the dynamic friction of soft rubber. Maybe at the drag strip they just take it for granted that the tires are going to spin out -- losing static friction.) On clay, of course, you are not going to maintain static friction -- that is why you slide. It could be that by filling in the tread with Shoe Goo I am making it harder for the shoe to maintain static friction, and might indeed may be making it easier on my knees to pivot my feet.

 

[ttbrowne]

Yes, well, an uncontrolled fall is likely to do any number of bad things to you knees. But I'd hardly compare a sudden slip on ice to having shoes with a little less traction. After all, we don't see people's feet suddenly sliding out from under them while playing on clay.

I agree that it would be better to use a harder rubber. But I'm not comparing slick soft rubber to slick hard rubber so much as shoes with deep tread versus shoes with shallow tread. As Charlie Federer points out, Shoe Goo rubs down quickly -- except between the treads. The effect, if there is any, is subtle -- it mostly just makes the treads shallower.

In fact, the point you raise about rubber hardness made me wonder about the mechanism of tread -- on sneakers as well as on tires. By channeling water, tread makes it harder for tires to hydroplane on puddles, but does it have any effect on dry surfaces? I know that drag racers use slick tires; is that to maximize surface area, or is that because the rubber on those specialized tires is too soft to stay together if tread were cut into them? Or, does tread help channel the road dust as well (drag strips being washed clean)?

One way that tread might improve traction (with rubber that is stiff enough to hold the cuts without tearing apart) is by providing a small amount of lateral "give" -- which makes it more likely that static friction will be maintained. (Static friction is considerably stronger than dynamic friction; the static friction of hard rubber will be stronger than the dynamic friction of soft rubber. Maybe at the drag strip they just take it for granted that the tires are going to spin out -- losing static friction.) On clay, of course, you are not going to maintain static friction -- that is why you slide. It could be that by filling in the tread with Shoe Goo I am making it harder for the shoe to maintain static friction, and might indeed may be making it easier on my knees to pivot my feet.

Frank,
Great response to an interesting problem.
On the drag slicks thing. A buddy down the street from me used to be a pit mechanic, he says they're used cause you want the most rubber, 100%, on the drag strip when racing. Traction. But for dry conditions only. They're not used for street use cause any moisture would cause them to hydroplane. Grooves are needed for street use. He said regular tires are set up to get rid of water in the grooves.

I like your last paragraph. Makes sense.

 

[Frank Silbermann]

Wish I'd read this before. I hurt my knee (meniscus) about two months ago. Getting the finals diagnosis Monday. It will not heal on it's own. I can't run at all. I can walk but there is pain. I DID get a new pair of shoes a week before I hurt it! I changed brands so it's starting to fall into place. Some university needs to do a study.

By the way, when I hurt my meniscus I went for two months trying to rest it, but daily life kept aggravating it and it just got worse and worse until I was on crutches. It was only on starting physical therapy and very consistently protecting the knee that it begin to heal. Your case, of course, will depend upon the location of the tear and the nature of the tear. From my reading:

If the tear is in the thin inner two-thirds, there is no blood supply and it will not heal. Surgery can remove any stray bits and round the ends of the tear so it doesn't continue tearing further. This usually results in a quick recovery and return to athletics, but you have permanently lost some cushioning and protection. This may lead to accelerated wear and arthritis in the distant future; less so if you keep your ligaments strong and tight.

If the tear is in the thick outer third, too much would have to be cut away for the above solution; it would cripple you. However, there is a blood supply so surgery would be recommended to sew the torn bits back together. Rehabilitation is much slower and longer, but if you do it right you could have a very satisfactory long-term result as all your knee parts will still be there.

In my case, the tear was in the outer third (just barely) but the torn parts were not separated, so the rest and rehabilitation alone seems to be sufficing in knitting them back together.

 

[danno123]

By the way, when I hurt my meniscus I went for two months trying to rest it, but daily life kept aggravating it and it just got worse and worse until I was on crutches. It was only on starting physical therapy and very consistently protecting the knee that it begin to heal. Your case, of course, will depend upon the location of the tear and the nature of the tear. From my reading:

If the tear is in the thin inner two-thirds, there is no blood supply and it will not heal. Surgery can remove any stray bits and round the ends of the tear so it doesn't continue tearing further. This usually results in a quick recovery and return to athletics, but you have permanently lost some cushioning and protection. This may lead to accelerated wear and arthritis in the distant future; less so if you keep your ligaments strong and tight.

If the tear is in the thick outer third, too much would have to be cut away for the above solution; it would cripple you. However, there is a blood supply so surgery would be recommended to sew the torn bits back together. Rehabilitation is much slower and longer, but if you do it right you could have a very satisfactory long-term result as all your knee parts will still be there.

In my case, the tear was in the outer third (just barely) but the torn parts were not separated, so the rest and rehabilitation alone seems to be sufficing in knitting them back together.

I've been having some left knee pain lately. It's not bad (yet) but I need to keep an eye on it. What physical therapy and exercises do you do for your left knee?

 

[charliefedererer]

I've been having some left knee pain lately. It's not bad (yet) but I need to keep an eye on it. What physical therapy and exercises do you do for your left knee?

Meniscus injuries can be very tough to design a rehab program for.

The problem is that any knee flexion/extension means pressure is put on the meniscus.

So exercise can make the problem worse, rather than better.

It takes months for the meniscus to heal, even if that is possible at all.

So the initial "exercises" are really unweighted range of motion movements to maintain range of motion, and not to continue losing strength as fast you normally would being off your leg. They are not designed to actually increase muscle strength.

If you are having knee pain, it is best to see an orthopod and have it checked out to see if what you really need is a period of rest.

Still, if you are curious the following site has a pretty specific meniscus rehab exercise progression:
http://www.sportsinjuryclinic.net/cybertherapist/front/knee/medial_meniscus/strengthening.php

But again, beware. For instance a later exercise, the squat, is listed as the best quad strengthening exercise. But it also a way to prevent an injury from healing.

 

[Frank Silbermann]

I've been having some left knee pain lately. It's not bad (yet) but I need to keep an eye on it. What physical therapy and exercises do you do for your left knee?

It seems like a dilemma; you need to stress the ligaments that hold your knee together, but not in a way that would risk the tissues that would be harmed if your knee didn't hold together.

But I read that when the knee is fully extended, the upper and lower leg bones settle into one another and lock. In that position, the actual knobs on the ends of the bones prevent the bones from sliding laterally against one another. So, to stress my ligaments while protecting my knee's stability, I do straight-leg isometric exercises. (The physical therapist had me do straight-leg isotonic exercises -- weighted straight-knee leg lifts in four directions, but I find that too slow and tedious.)

I stand with my feet about a foot apart and my knees locked, and I tighten my hamstrings as though I were trying to straighten my leg beyond the lock-up point, and hold the max-force contraction for ten seconds. I do that five times.

Then, standing with my feet a foot apart and with legs straight and knees locked, I try with all my might to bring my feet together (but I cannot). I hold the contraction for ten seconds, five times. Then I do the same, but this time trying to push my feet further apart (as though I were trying to cause the carpet to split between my feet).

Then I bring my feet together and, as always with locked knees, I make a maximal (but unsuccessful) effort to slide one foot forward and the other backwards. Ten second contraction, five times. Then I do that the other way.

The above exercises stretch and strengthen the various ligaments that help hold your knee together (by having the muscles pull on them) without causing any unwanted side-to-side slippage in the knee itself. It does this without putting any extra weight on your knee, other than your normal body weight. (If it hurts even just to stand, then you're not ready for these exercises, and maybe you should begin with the lying-down straight-leg raises in each of four directions, going to increasingly heavy ankle-weights. I do the standing exercises as a maintenance program.)

Another exercise I do VERY CAREFULLY is to put my weight on my left foot with knee straight, and using my hands on a desk I try to rotate my body to the right, stretching my hip and ankle to allow my foot to rotate leftward relative to my body, and hold the stretch for thirty seconds. This is the kind of rotation that caused the injury in the first place when I did it with a bent knee while pivoting, but keeping my knee fully extended protects my knee so that the other joints are stretched.

Note that in none of these exercises involve any motion of the knee parts relative to one another, and the interlocked bones prevent the knee from giving way.

Another exercise that is good is to sit with one's bad leg off the floor and to flex and straighten the knee twenty-five times against no resistance whatsoever. Because there is no resistance, there is no stress on the knee and minimal friction. But the motion helps stir the fluid inside and polishes the surfaces of the knee (in my imagination at least). This is analogous to the low-resistance stationary bike-riding that the physical therapist had me do to start each session.

But the most important point about rehabilitating a meniscus injury is not to do anything that hurts.