Osteoarthritis of the knee
It is the result of progressive wear and tear and loss of articular cartilage that can eventually lead to limiting disability over time, although the rate of progression varies for each individual. It is the most common type of arthritis diagnosed, with an annual incidence of 240 cases per 100,000, but continues to increase today as life expectancy and obesity increase.
Knee osteoarthritis is the result of articular cartilage degeneration for which the cause is currently unknown. It is usually thought to be age-related wear and tear, but also to the disease condition itself, since there are differences in the cartilages of osteoarthritis and aging. In addition, there is an elevated expression of enzymes responsible for cartilage degradation in osteoarthritis of the knee compared to normal values in normal aging.
However, in addition to an inherited tendency to develop osteoarthritis, or certain hereditary characteristics such as bowleggedness, knock knees or joint laxity, there are several additional factors that may contribute to an increased risk of developing knee osteoarthritis:
- Age: the risk increases with advancing years, although it usually appears after the age of 40.
- Gender: women are more prone, although the reason for this is unknown.
- Overweight or obesity: a body mass index (BMI) of 30 or more is a major risk factor, increasing the likelihood of knee osteoarthritis by up to 7 times given the added stress on the joints. In addition, fat tissue produces proteins that can cause inflammation in and around the joints.
- Knee injuries, joint deviations or deformities.
- Frequent overloading of the knee in a work or sports context.
- Diseases: gout, rheumatoid arthritis, metabolic pathologies such as hemochromatosis due to iron deposition in the joints or growth hormone overproduction defects can increase your risk of having this disease.
Knee osteoarthritis is a multifactorial disorder resulting from complex interactions between a number of genetic and environmental risk factors that contribute to both its onset and progression. A GWAS study conducted in recent years on nearly 25000 cases and over 4000000 controls has identified 11 risk loci involved in chondrocyte and osteoblast biological pathways implicated in susceptibility to osteoarthritis, which could also result in potential new therapeutic targets.
Symptoms of osteoarthritis often develop slowly and worsen over time. Pain is the most common symptom of osteoarthritis of the knee both at motion and at rest. Additionally other possible symptoms that may occur include:
- Stiffness, locking or tenderness of the joint, especially after a long period without motion.
- Loss of joint flexibility.
- Swelling, warmth, or inflammation of the knee.
- Presence of hard lumps (osteophytes) around the joint.
- Clicking or popping during movement.
- Weakness of the joint in an upright state.
Although osteoarthritis of the knee cannot always be prevented, there are measures that may help reduce the risk of developing it:
- Maintain a healthy weight.
- Rest and seek a minimum of 6-8 hours of restful sleep each day.
- Incorporate strength exercises as much as possible to strengthen the muscles in the area and reduce wear and tear on the joint itself.
- Limit the impact of physical exercise on the knee, performing exercises such as swimming or cycling, and in the case of jogging or running do it on grass or soft ground and avoid compact surfaces.
13.5 million variants
Hsu H et al. Knee Osteoarthritis [Updated July 2021]
Tachmazidou I et al. Identification of new therapeutic targets for osteoarthritis through genome-wide analyses of UK Biobank data. Nature Genetics. 2019 Feb;51(2):230-236.