[Medical Q&A] What factors may be at play when you suddenly develop knee osteoarthritis?

Author: Qi Pan, deputy chief physician of China Rehabilitation Research Center

Reviewer: Ma Lifeng, deputy chief physician, Beijing Friendship Hospital, Capital Medical University

Knee osteoarthritis is a chronic bone and joint disease caused by cartilage degeneration and bone hyperplasia in the knee joint, also known as "proliferative arthritis of the knee joint", "degenerative arthritis and osteoarthritis, etc." The causes of the disease are as follows.

The first and most important factor is age. Knee osteoarthritis often occurs in the middle-aged and elderly population, and its prevalence increases with age. If the human body is compared to a car, the knee joint is like the bearing of the car. When the cartilage on the surface of the knee joint and the meniscus between the joints degenerate and wear, resulting in the exposure of the subchondral periosteum, pain will follow.

Secondly, weight is the second most important factor affecting knee osteoarthritis. As one of the most important weight-bearing joints in the human body, the greater the weight, the greater the pressure on the knee joint, and the faster it will wear out.

Thirdly, the decrease of estrogen level is also an important factor causing knee osteoarthritis. The incidence of knee osteoarthritis in women is often higher than that in men, which is mainly determined by estrogen level.

Finally, a factor that is easily overlooked is the atrophy of the quadriceps. The quadriceps, as the knee extension device, is the most important group of muscles in the knee joint. When the quadriceps become weak, the stability of the knee joint will decrease, and the abnormal impact of the knee joint will increase, which will easily lead to synovitis and joint effusion, and further knee pain. Knee pain will lead to reduced or limited activity, leading to further disuse atrophy of the quadriceps, thus forming a vicious circle and accelerating knee pain and degeneration. Therefore, many elderly patients with knee osteoarthritis have a "fear of squatting".

In addition, people at high risk of knee osteoarthritis also include those who kneel, squat, bend their knees, and bear weight for a long time. A history of knee trauma is also an influencing factor.