One of my first anatomy lessons came from a rodeo clown yelling to an announcer.
Aaaauuuugghhh! He got my knee. That bull got me in the knee.
He what?
My knee!
Oh. You're walking kind of funny. Did he hit your left knee?
Nope.
Your right knee?
Uh-uhhh.
What? Well then which knee did he get ya?
It was my HIGH knee.
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That heiney bit was hilarious when I was a kid. A recent experiment here at home has confirmed its continued effectiveness in young populations. But it's no wonder that many older folks groan and roll their eyes. The twenty seven million Americans suffering knee osteoarthritis (OA) are in no mood for dumb knee jokes. It has been estimated that of all joints, the knee is most frequently affected by OA and leads to the greatest loss in function.
The role of physical activity in causing and treating osteoarthritis has been studied and reviewed. What we know is what you could have guessed.
-High impact activities and traumatic injuries to the knee are bad.
-There's a downward spiral of pain, decreased activity, and generally poor health.
-Low impact exercise and not being overweight are helpful, so those with knee pain should walk and stretch and quit doing anything fun like tennis and skiing and mountain biking.
King hippo probably had bad knees.
-If you still have debilitating pain after you've quit doing anything fun and tried conservative treatments like anti-inflammatory medications and injections of corticosteroids and lubrication, then you're a good candidate for knee replacement.
-Knee replacements do reliably reduce pain and improve self-reported quality of life in 90% of patients. Yay.
-Knee replacement is a major ordeal. D'oh. You can expect about three days in the hospital, unless the new joint gets infected. Then you go home and have at least a month of increased crabbing around and depression due to pain, constipation, restless nights, and thrice-weekly trips to your
choice of rehabilitation specialist.
And here are a few bits of evidence that we probably wouldn't have guessed:
-Patients generally plateau in their recovery by about six months after surgery, and function begins to decline at about two years after surgery. A new knee won't keep you from getting older. Sorry.
-Although most patients have much less pain and recover to preoperative levels of strength and range of motion by about six months after surgery, they still exhibit the EXACT same level of functional limitations.
-"Preoperative level" does not imply good strength. People are painful and weak in the legs going into surgery, and pain free and STILL VERY WEAK well after surgery. It is thought that this strength deficit holds the key to the unfortunate stats below.
-Compared to adults without significant knee pain, those who have had knee replacement surgery exhibit 18% slower walking speed, 51% slower stair-climbing speed, and a 40% leg strength deficit. They report having greater difficulty kneeling, squatting, moving laterally, carrying loads like groceries, exercising and playing light sports, dancing, gardening, and participating in sexual activity.
Don't ask me, that's just what the literature says.
I'm unsure what else we can gather from all this. Knee replacement surgery helps with pain but not with function. Some people are content with that. But I can add just a few points of personal observation for those of you kneeling on the brink of a trip to the orthopedic doc.
-Despite your neighbors friends uncle who experienced Job level devastation after having his knee replaced, the orthopedic docs are great at selecting appropriate candidates for surgery. In the clinic at three weeks after surgery, almost everyone regrets having gone through with it. On a scale of zero to ten, their pain is rated right around "you-know-where-you-can-shove-your-scale." And by about two or three months, those same folks very rarely regret having surgery.
-There's definitely an
x factor here, an unknown. The
x may have to do with expectations and other deep psychology that's hard to quantify. It may have to do with other unmeasurables involving blood chemistry and inflammatory response.
You may be a fit, active, and otherwise healthy adult. But that won't make an ounce of difference in how your body handles the pain, swelling, and other miseries due to the controlled trauma of orthopedic surgery. Some knowledgeable dude just subluxed your kneecap, hacked off the ends of your femur and tibia with a fancy saw, jammed a peg into the marrow, added some glue to hold everything together, and stitched it back up. Your morning green tea and years on the elliptical probably has little to do with all that (though your omega-3 fatty acids might).
Take ginseng in order to...do more pirouettes on the beach?
-Why is it that with or without surgery, those with knee OA function about half as well as people without significant knee pain? Is it ginseng? I truly don't know, but the literature indicates that it's NOT just the pain.
There are other, mechanical factors that do exist and can help, though they're extremely difficult to quantify. Are there nuances to your habits and how your body moves? What chewed up your knees to begin with? I bet there are imbalances in strength or flexibility or motor control of your ankles and hips and core. I bet you walk with increased transverse plane (torquing) motion at the knee and/or move with a knee dominant pattern that doesn't allow the strong hip and pelvic muscles to perform their stabilizing roles. It may not be the case. But if I were a bettin' man...
-Pretty much everyone with knee pain has to sit on the sidelines far more than they would like, and this sitting has propitiated poor balance and an "I can't" mentality. That's one of many reasons it's probably not a great idea to give grandma a new knee and then send her back home without a lot of ongoing work.
-Surgery or no surgery, it's worthwhile to explore these things. It's important not to expect a pain free existence. I've seen some people who have worked on their functional strength and balance and movement patterns, and despite a pretty bad x-ray, were able to manage quite well without knee surgery. And I would certainly think that even if the effort doesn't save you from surgery, it holds value for gaining peak recovery, so you're not functioning at half capacity like the literature reports.
-On a final note, us rehab folks focus a lot on getting that knee flexibility back. You need to get the knee straight to allow a grossly symmetrical gait pattern. You need at least 110 degrees of bending to allow stairs, stooping and such. But the literature suggests that the most important factor for improved function is not flexibility, but strength.
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| Get up and working on your feet, a.s.a.p. |
"Successful" knee replacements with little pain and adequate flexibility
still show limited strength, and strength dictates function more than anything else. So the latest thought is that really pushing the strength training is critical, especially in that first month after surgery when strength plummets the most. That means pushing 20 pounds instead of 2 pounds on that exercise where you sit and kick the leg out. It means challenging your limits in balance and doing lunge variations and steps-ups if you can, rather than 3 sets of 100 leg raises and heiney squeezes.
So there you have it. Osteoarthritis is a pain in the knees. I got lazy bones typing here at the end, but references are available upon request. Except for the heiney part. I refer you to the expert testimony of rodeo clowns.
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