Without knees, your legs would just be two rigid columns extending from torso to feet.
Imagine the lumbering walk and all the other daily movements that would become far more awkward in a knee-less existence. Sitting and standing would both take enormous effort, and something to hold on to.
Like everything else we take for granted, we don’t typically consider our knees until they become a problem. But when this joint starts to hurt or fail, it’s clear how much of your mobility depends on it.
Doctors who work with this joint say knee problems have become incredibly common—impacting a quarter of all adults. Over the past 20 years, complaints of knee pain have increased 65 percent, resulting in nearly 4 million primary care visits annually. Many of these visits are for replacement parts. The number of knee replacements performed in the United States has more than doubled over the course of the 2000s, with more than 600 thousand now done each year. Experts predict that by the year 2030, we will see about 3 million knee replacements annually.
So what makes this joint increasingly prone to problems? Is there a design flaw that leaves knees at the mercy of injury and malfunction? Dr. Eugene Charles, a Manhattan-based chiropractor and director of the Applied Kinesiology Center of New York, doesn’t think so. Charles calls the knee “the Ferrari of joints,” in reference to its high-performance design. He says the problem is that we run our knees too hard, and don’t give them the attention they need.
“The knee is perfectly designed, but we don’t use it optimally,” Charles says.
The knee is the largest joint in the body and the most complex. It consists of the body’s two largest bones—the tibia (shin bone) and femur (thigh)—as well as two smaller bones: the patella (knee cap) and the fibula (calf). This skeletal structure creates a familiar hinge, but the knee does so much more.
In his new book, “Journey to Healing: The Art and Science of Applied Kinesiology,” Charles devotes a whole chapter to the knee. He says that what makes the design of this joint so special is that it not only bends but rotates slightly. This rotary movement is what allows us to perform all kinds of everyday activities like squatting, climbing, sitting cross-legged, kicking, and dancing. But it can also open the door to instability.
“What I see in practice and what generally goes unrecognized is that knees slip out of place very subtlety,” Charles said. “It doesn’t show up on MRIs or CAT scans, and it either causes degeneration or sharp pain.”
Charles looks for these small misalignments with what he calls a “gait analysis.” Basically, he watches how patients walk, and their movement reveals asymmetries in the body. These imbalances are often caused by seemingly minor habitual movements that can, over time, throw our knees slightly out of whack.
“Going up the stairs is big,” he said. “For people who try to cover as much of the stairs that they can, a lot of times they twist their foot to get more of it on there. I’ll watch people go upstairs sometimes and say, ‘Oh boy. That knee is going to be out soon.’”
Another common movement that leads to misalignment is getting out of a car. Charles says he can often tell the drivers from the passengers based on which knee has problems.
“They lift that leg out of the car, and they’ll turn their foot out and push it up,” he said. “Once is no big deal, but after 1,000, 2,000, or maybe 4,000 times of doing it, the knee just slips out a little bit.”
Charles uses hands-on techniques to set out-of-joint knees back into place. But he says that most of what keeps our knees properly aligned, strong, and long-lasting is our responsibility.
“If you’re overweight, it increases the pressure on the knee insanely,” he said.
The knee is known primarily as a bending mechanism, but another critical aspect of this joint’s design is that it can carry a lot of weight.
The knee absorbs one-and-a-half times your body weight when you walk on flat ground, and absorbs double or even triple your weight when you go up or downstairs. Knees have to bear five times your weight when you squat. This means that if you weigh 200 pounds, your knees must withstand 1000 pounds of pressure when you bend down to tie your shoes.
Thus, the more you weigh, the more weight your knees are forced to carry. That’s why experts say that one major reason our knees wear out faster than the rest of our body is because of excess pounds. Research has found that obese young people who are able to shed as little as 10 to 15 pounds have a much lower risk of osteoarthritis later in life.
“Ten extra pounds of body weight adds 40 extra pounds of pressure to your knees. And a lot of us are a lot more than 10 pounds overweight,” Charles said.
Losing weight can lighten the load, but it can also take a long time to lose, especially if our joints hurt. Fortunately, there are things we can do right away to increase our knee’s ability to bear the weight it must carry, and make us more inspired to do regular exercise.
There are about 12 different muscles involved with the knee—including the quadriceps (front thigh muscles), calves, and hamstrings. Even part of the glute extends to the knee. The individual area of weakness can vary, but those who work closely with this joint often point to a few common locations.
“You’re only as strong as your weakest link, and almost every physical therapist in the world knows the medial [inner] quadricep is almost always weaker on people than the outer one,” Charles said. “This imbalance allows the bottom part of the knee to slip out very easily. If everything was balanced and that medial quadricep was strong, it probably wouldn’t rotate out as much.”
Krissi Williford, an exercise physiologist at Xcite Fitness in Birmingham, Alabama, traces most of the knee problems she sees to underactive glutes (buttock muscles). Williford says that chronically weak glutes can’t support their share of the body’s weight and movement, so the burden falls on the already imbalanced quadriceps.
“The main thing I see is that the glutes are underactive, and sometimes completely turned off. I know it sounds crazy to say your muscle turned off, but your nervous system drives everything. It’s like the electricity behind the light switch. If the connection is disrupted, then the muscle can’t work because it has no power, so to speak,” Williford said. “I see it all the time.”
It might seem strange to think a knee problem is related to a weak buttock muscle, but consider that your joints don’t work in isolation. Even relatively distant parts of the body might be the root cause for knee pain.
“I’ve even seen knee pain because a shoulder didn’t work well. Everybody is different, and the reason you have knee pain is very individual,” Williford said.
According to Alice Holland, doctor of physical therapy and director of Stride Strong Physical Therapy in Portland, Oregon, the main reason the knee bears so much of the body’s burdens is that it’s an “in-between joint.” It’s at the mercy of what’s above and below it.
“Muscles and bones in the foot control foot placement, and large muscular systems control hip and core movement of the torso,” Holland said. “The knees are caught in between these two systems and are usually passively placed according to what the body’s movements are. With torque, twisting, collapsing and lateral movements, the knee can be bent and twisted into positions that cause pain and damage.”
We often associate knee problems with the elderly (arthritis) or athletes (think “runners’ knee” or ACL damage). But really anyone who habitually asks more of their knees than what they were trained to deliver can experience pain and malfunction.
If your knees are weak, even the most basic movements might be more than this joint can tolerate. However, with regular practice, a few simple exercises you can make your joints stronger than ever.
“Sometimes this might induce slight amounts of pain and discomfort because to strengthen your lower extremity you would have to strain it first with progressively tolerable demands and exercises,” Holland said. “But the stronger and more balanced your muscles are in the lower extremity, the less joint shear force you will have from your activities.”
Building Better Knees
The key to better knees is to strengthen them, but Charles says too often people only focus on knee tightness, and ignore the underlying weakness. “They use massage, or foam-roll it,” he said. “But if a muscle is tight, there is usually a muscle weakness causing the tightness.”
There are many exercises designed to strengthen the knee. For sedentary and elderly individuals, Holland recommends practice climbing stairs and curbs. For more active people, sprinting, lateral movements, pivots, deep lunges, and jumps can all help to improve your knee game.
A widely prescribed movement to activate a weak glute is called the clamshell. It’s done lying on your side, knees bent. Ankles stay together while the top knee slowly lifts and lowers, mimicking a clam.
Whatever the exercise, keep in mind that your goal is a stronger, more mobile structure. That’s why proper alignment and body mechanics is crucial to successful knee exercises. Charles advises that people consult a physical therapist or personal trainer to make sure they’re performing movements correctly.
“The lunge, when done properly, is a very good knee exercise. But sadly most people do it improperly,” Charles said. “They’ll let the knee go in front of the toe as they’re lunging forward, and that’s bad news. That’s a knee problem about to happen.”
Treating Problem Knees
Pain is an easy-to-read indication of a knee problem. But Dr. Steven Struhl, a board-certified orthopedic surgeon and knee specialist, says recurrent swelling is a sign of more serious trouble.
“Popping, clicking, giving way, and poor stair tolerance are all additional clues that the knee is becoming problematic,” Struhl said. “Loss of motion and gait disturbances often suggest more advanced disease and require immediate evaluation.”
Struhl agrees that the mainstay of treatment for knee problems is physical therapy. However, for extremely inflamed knees, injections may be necessary.
“Traditional methods such as cortisone are highly effective but often give only short-term relief. Newer ‘regenerative’ injections such as PRP may be far more effective,” Struhl said.
PRP stands for “platelet-rich plasma.” The process involves taking either a blood sample or stem cells from bone marrow, concentrating it in a centrifuge, and then re-injecting it back into the knee to neutralize inflammation.
Taking care of our knees can help us avoid such procedures. Struhl suggests that the quality of our diet can influence this joint. Charles says good fat is particularly important for feeding healthy knees.
“Every joint in your body needs oil like a car needs oil, and most people are three quarts low,” Charles said.
“You can have olive oil, and avocados. Omega 3 oils are fantastic. It’s for lubrication, and acts as an anti-inflammatory for this hard-working joint.”
Another important knee nutrient is protein. This feeds all the tissues in the joint, such as muscles, tendons, and the meniscus—a cushion inside the knee joint that prevents bones from rubbing directly on top of one another.
“Gelatin is a fantastic old-time cure,” said Charles. “I’ll regularly tell people to take two packages of Knox gelatin and put it in their oatmeal. Gelatin is actually collagen—the most abundant protein in the body. It’s great for your joints, and it’s great for the meniscus in the knee.”
However, when serious structural damage is discovered, surgery may be necessary. Struhl explains that surgery ranges from simple removal of torn tissue to reconstructive techniques to rebuild lost structures such as ligaments or cartilage. The most extreme is a prosthetic replacement for end-stage arthritis.
But if we can learn to maintain our knees before they fall apart, they should be able to last as long as we do.
“If body parts were meant to be replaced, they would have a warranty,” Charles said. “Keep them in alignment. Keep the muscles balanced. Keep your weight down. Stay hydrated. Get enough protein and oils, and your knees will really take you where you want to go.”