Knee pain can be anything from a small nuisance that one could shrug off to a rather disabling condition. For some, the difference lies in what activity they’re doing. Our knees can be calm when seated and then creak like an unoiled gear when we try to stand up. They may be able to handle leveled ground but protest with pain when moving up and, especially, down the stairs.
So why are our knees so fussy and what can cause these aches and pains? To fully understand the why, we need to get to know the knee joint itself.
Healthy knee mechanics
A well-functioning knee can be extended completely straight and can be bent to touch all the way to the back of your thigh. You can turn them inward towards the other leg. Just so, you can turn them outwards and away from the body. All these movements are made possible because the knee joint is the meeting place of several parts of the human machinery. Problems in any of these specific parts can lead to some amount of pain. Of course, the joint itself and the bones are important (and we’ll get to them soon). But when it comes to walking downhill, we need to pay extra attention to the muscles.
Now, there are several muscles that move the knee, turn it inward, and outward. But we’re going to focus on two sets of them. The quadriceps femoris are the muscles found on the front side of the thigh. These muscles help extend your knee outward, like when you’re kicking a ball to the other side of the field. The biceps femoris, in contrast, are situated behind the thigh and they pull the joint to bend the knee.
Several years ago, researchers studied the minute body stresses that healthy adults feel when walking on a flat surface as opposed to when descending downwards. They found that, when walking downhill, there is greater stress and movement on the knee joint as compared to other leg joints, such as the ankle. This may lead to muscle soreness around the knee when walking downwards, particularly by healthy mountain trekkers. A more recent study concurred that muscle soreness was worse after walking downhill compared to uphill due to some mild muscle damage on downhill walking specifically.
Walking downwards also results in a more extended knee compared to walking up the stairs. What this does, besides putting more load on the muscles, is to increase the compressive force on the knee joint by 3-4 times. To put it simply, your knees would be holding up the weight of your body fourfold as it descends the stairs. For such a large weight to be dependent on a small surface area, no wonder this strains the knee joint.
Now, these are examples of how downstairs descent or downhill walking affects healthy knees. But individuals who complain of knee pain are more likely to have problems with the joint. So how does going down the stairs affect these knees?
Osteoarthritis and walking down the stairs
The results of a 2017 study pointed out that patients with knee osteoarthritis may have joint instability on their knees when walking downhill. Thus, the joint may not be able to handle the weight of walking downhill. Because of osteoarthritis, the already unstable leg is more likely to bow when walking downwards. This can end with worse symptoms and greater joint damage.
And the problem doesn’t just stop with the joint itself. Patients with knee osteoarthritis have greater muscle strength deficits, especially with the quadriceps that extend the leg. Hip abductors, or the muscles that move the leg away from the body, were also identified as having less strength when descending the stairs. Even in patients with early-stage knee osteoarthritis, decreased strength of the hip abductors was associated with knee pain while walking down the stairs.
So going down the stairs can exacerbate knee pain in several ways. But it’s not like we can just float downwards for the rest of our lives. Having a room on the first floor of the house is simply not an option for everyone (though it is ideal for seniors with osteoarthritis). What can we do to combat knee pain?
Treating knee pain
Short-term treatment for knees that are aching more than one can handle would be over-the-counter oral analgesics. The most common are your nonsteroidal anti-inflammatory drugs (NSAIDs) and paracetamol. Exercise-based therapy is also effective in easing the pain, especially if you have a condition like knee osteoarthritis or patellofemoral pain syndrome. If one has osteoarthritis, weight loss should be encouraged as your weight can be felt by the knee as much as fourfold and cause further damage.
But what about for the long-term? Are there things we can do to prevent knee pain during stair descent?
Have you considered walking backwards? Yes, it’s a little unconventional but a 2010 study goes into the benefits of this strategy. It argued that when walking down the stairs facing forward, the center of body mass and thus the load will fall on the knee and ankle joints. In contrast, descending backwards would mean that the weight of the whole body would be held by the hip joint-- a much larger and more stable joint that could compensate for these functional defects.
There are gait modification strategies that have been used to decrease the amount of weight the knee has to carry while going down the stairs. This refers to changing how we normally walk. A study suggests that stepping first with your forefoot as opposed to stepping first with the rear foot, closer to the ankle, helps prevent knee pain from becoming worse.
Do not discount a potential knee injury!
These are all fine and dandy for knee pains that are caused by overuse, joint stresses, or chronic conditions such as osteoarthritis. However, knee pain can also be caused by injuries to any of the structures surrounding the joint. When in doubt, especially for persistent pain, it is always best to consult your trusted healthcare practitioner.
A lot of things can cause the creaking pain when you go down the stairs. Much of it boils down to the mechanics of the knee joint and how it can best hold the weight of your body. But because of this, there are several ways to combat this and make sure it doesn’t progress.
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