Knee arthritis is often perceived to be an inevitable part of growing old and something that is passed down from parents in the same way that eye color or the tendency to get colds are. However, when examining what causes arthritis in the knee, it becomes apparent that although age is a factor, there are many other factors that are far more actionable, and far more connected to daily habits, body mechanics, and past injuries than most people realize.
Read on to learn about the primary risk factors for knee arthritis, how they interact and what you can do to prevent the onset of arthritis. If you are currently suffering symptoms, the Kneeflow team has put together resources to help you understand the inflammation side of this condition as well.
The first one: Excess Body Weight and Joint Load
Your weight impacts your knees significantly. For every pound of excess body weight that you carry, your knees are subjected to an additional 4 pounds of pressure when you are walking. As you walk down stairs or up and down hills, this increased pressure puts on the radio. Over time, this cumulative load accelerates cartilage breakdown in ways that go beyond simple wear.
Excess body weight also leads to chronic low-grade inflammation in the body. The fat tissue, especially the visceral fat, releases inflammatory mediators. These do not stay local and can travel to almost any tissue in the body including the joints. As such, obesity is one of the most significant modifiable risk factors for what causes arthritis in the knee, not just a mechanical issue but a metabolic one.
Previous Knee Injuries
Downturns in knee health can begin with seemingly benign injuries such as a torn ACL, a meniscus injury or even a fracture near the joint line. Years or even decades can pass and eventually these events can lead to arthritis of the knee in what is called post-traumatic arthritis, particularly in people who were active in their twenties and thirties.
Many people don’t realize that the structure of a joint injured in the past continues to put uneven stress on cartilage, while also the biologic changes that have occurred with the injury, significant knee injuries trigger inflammatory responses that, if not fully resolved, can leave the joint in a low-level state of ongoing inflammation. That environment is not kind to cartilage over time.
Genetics and Family History
A history of parents or other relatives with knee arthritis increases an individual’s susceptibility above average. Whilst individual genetic factors do not predetermine arthritis, the interaction of multiple genetic influences on aspects such as cartilage, bone, joint shape and inflammation can increase susceptibility that other risk factors can hit harder.
Understanding what causes arthritis in the knee for you specifically sometimes means looking at your family history not as a prediction, but as a signal to manage the controllable variables more carefully.
Repetitive Stress and Occupational Risk
There is considerable evidence that individuals in jobs that require prolonged kneeling or squatting, or heavy lifting and carrying, have an increased risk of developing knee arthritis. Many of these individuals are in construction, farming or in cleaning work.
Cartilage is designed to recover from loads in time and with variation. The mechanism is straightforward. Repetitive loading in the same pattern does not give the joint the recovery cycles it needs, and it concentrates stress in predictable spots rather than distributing it across the joint surface.
Muscle Weakness and Poor Joint Support
Knee arthritis occurs when the muscles around the knee, such as the quadriceps, hamstrings and hip abductors, fail in their role to support the joint and distribute load. As these muscles fail, more load is placed on the knee and the joint is forced to bear the extra load. This is also one of the reasons why knee arthritis and muscle weakness tend to exist in a feedback loop.
Pain discourages movement, reduced movement leads to muscle atrophy, and less muscle support makes the joint more vulnerable to further damage. Breaking that cycle often requires deliberate, low-impact movement even when the knee is uncomfortable. If you want to understand more about how inflammation fits into this picture, Kneeflow's breakdown of why knee arthritis happens and what drives inflammation is a useful companion read to this piece.
Joint Alignment and Structural Issues
The malalignment of a knee, whether due to birth or injury, results in an unequal distribution of load across an individual’s joint. A slightly medially deviated knee places uneven stress on the anterior compartment of the knee, while a laterally deviated pressure on one compartment of the joint rather than spreading stress evenly. Over years of walking, that imbalance adds up.
There are a number of conditions that affect the legs, such as bowlegs or knock-knees, which can have similar long term effects even when not particularly noticeable. The way the foot functions, the position of the hip and how a person gait patterns all feed into how the knee is loaded, which is part of why addressing knee arthritis effectively often requires looking beyond the knee itself.
Sex and Hormonal Factors
The incidence of knee arthritis in women is greater than that in men, particularly after menopause. Estrogen appears to have a protective effect on the cartilage and soft tissues of joints. As estrogen levels decline after menopause, the risk for developing arthritis of the knee increases.
The female pelvis has several anatomical characteristics that can influence the knee’s position and how it distributes weight. As a result, there are additional mechanical stresses on the knee that must be taken into account when determining what causes arthritis in the knee in women requires accounting for this hormonal layer alongside the structural and lifestyle factors that apply across both sexes.
Inflammatory Conditions and Autoimmune Triggers
When talking about arthritis in the knee it is generally referred to as osteoarthritis but there are many other types of arthritis that can affect the knee. These include rheumatoid arthritis, psoriatic arthritis and gout. All of these are inflammatory/immune related conditions.
Rheumatoid arthritis is what causes arthritis in the knee when the immune system attacks the joint lining directly. In gout, uric acid crystals accumulate in the joint space. In psoriatic arthritis, systemic inflammation associated with a skin condition targets the joints. Each of these conditions has its own causes and its own treatment pathway, but all of them can ultimately result in joint damage that mirrors what causes arthritis in the knee through mechanical means.
What You Can Actually Change
Many of the factors above are beyond our control. However, a significant number of the factors that contribute to the risk of knee problems can be modified.
Losing weight and maintaining a healthy body mass reduces both mechanical stress and systemic inflammation. Strengthening the muscles around the knee increases the joint’s dynamic support. By modifying your movements during work can reduce repetitive stress patterns. Getting acute knee injuries properly evaluated and rehabilitated lowers the risk of post-traumatic arthritis down the line.
None of these changes eliminate risk entirely, but they shift the odds in ways that accumulate over time.
Closing Thoughts on What Causes Arthritis in the Knee
Knee arthritis can develop from a variety of inherited, acquired and activity-induced factors. Understanding what can cause arthritis in the knee helps you understand where you have control and where you need to make changes to manage your knee discomfort instead of preventing arthritis altogether.
If you are looking for support while you manage daily knee discomfort, the Kneeflow team is here to help. Reach out through our contact page and talk to us directly about what you are dealing with.
