Silver Age Health丨How can the elderly protect their knee joint health?

As time goes by, the first thing that middle-aged and elderly people feel is the subtle changes in their knee joints, which are important joints that support our walking. This article aims to study how to maintain them scientifically during exercise, so that we can still enjoy a vibrant life in our later years and avoid being troubled by joint problems. While pursuing health, we should pay attention to the maintenance of our knee joints, continue the fun of activities with scientific methods, and make the elderly life more exciting.

▏The exquisite structure of the knee joint

The knee joint is a synovial joint with a delicate and complex structure. It is composed of multiple parts that work together to maintain the normal function of the knee joint.

1. Skeletal structure The femur, tibia and patella form the basic skeletal framework of the knee joint. As the longest and strongest tubular bone in the human body, the lower end of the femur swells to form the medial and lateral condyles, which correspond to the medial and lateral condyles at the upper end of the tibia to form the main articular surface. The two articular surfaces are not completely flat and fit together, but have a certain curvature and concave-convex structure. This special design increases the stability of the joint while allowing the knee joint to flex and extend and a certain degree of rotation. The patella, commonly known as the kneecap, is located in front of the femur and is connected to the tibial tubercle through the patellar ligament. It not only protects the front of the knee joint, but also plays an important lever role in the flexion and extension of the knee joint, enhancing the power transmission of the quadriceps femoris and assisting the knee joint in completing various complex movements.

2. Cartilage tissue Articular cartilage covers the articular surfaces of the femur, tibia and patella, and is a layer of smooth, elastic connective tissue. It acts like a "lubricant" and "shock absorber" for the joints, reducing friction between the articular surfaces and buffering the impact generated during movement. Articular cartilage is mainly composed of chondrocytes and extracellular matrix, which contains collagen, proteoglycans and water. Collagen forms a tough fiber network that provides mechanical support for cartilage; proteoglycans have strong water absorption, which can maintain the moisture content of cartilage and give cartilage good elasticity. In normal joint activities, articular cartilage is constantly subjected to pressure and friction, but with its unique structure and metabolic mechanism, it can maintain its integrity and function.

3. Meniscus Meniscus are two semilunar fibrocartilages located between the femoral and tibial articular surfaces, called the medial meniscus and lateral meniscus respectively. They act like "cushions", further enhancing the stability and cushioning capacity of the knee joint. The lateral edge of the meniscus is thicker and closely connected to the joint capsule; the medial edge is thinner and free in the joint cavity. The upper surface of the meniscus is concave and conforms to the femoral condyle; the lower surface fits the tibial plateau and is relatively flat. This special shape enables the meniscus to deform as the articular surface changes during knee joint movement, effectively dispersing pressure and reducing wear on articular cartilage. In addition, the meniscus also has a certain proprioceptive function, which can sense the position, direction and speed of the knee joint, provide feedback information to the neuromuscular system, and help maintain joint balance and coordinated movement.

4. Ligament system The ligament system of the knee joint is like a strong "rope" that tightly connects the bones together, limits the excessive movement of the joint, and ensures that the knee joint moves within the normal physiological range. The main ligaments include the anterior cruciate ligament, the posterior cruciate ligament, the medial collateral ligament, and the lateral collateral ligament. The anterior cruciate ligament is located inside the knee joint, starting from the front of the intercondylar eminence of the tibia, slanting posteriorly and superiorly, and ending at the medial surface of the lateral condyle of the femur. Its main function is to prevent the tibia from shifting forward relative to the femur, while limiting excessive extension and rotation of the knee joint. The posterior cruciate ligament starts from the back of the intercondylar eminence of the tibia, runs forward and superiorly, and ends at the lateral surface of the medial condyle of the femur. Its function is opposite to that of the anterior cruciate ligament, mainly preventing the tibia from shifting backward relative to the femur and limiting excessive flexion of the knee joint. The medial collateral ligament and the lateral collateral ligament are located on the medial and lateral sides of the knee joint, respectively. They connect the medial and lateral condyles of the femur and tibia. Their main function is to prevent excessive lateral displacement of the knee joint in the medial and lateral directions and maintain the lateral stability of the knee joint. 5. Synovium and synovial fluid The synovium is the inner structure of the knee joint capsule, which covers all structures in the joint except the articular cartilage, meniscus and ligament attachment points. The synovial tissue is rich in blood vessels and nerves and can secrete synovial fluid. Synovial fluid is a transparent, viscous liquid whose main components include water, hyaluronic acid, protein and electrolytes. Synovial fluid is like a "lubricant" for the joint, which can fill the joint cavity, reduce friction between the joint surfaces, provide nutrients for the articular cartilage and meniscus, and take away metabolic waste. Under normal circumstances, the process of synovial secretion and absorption of synovial fluid maintains a dynamic balance to maintain normal pressure and synovial fluid volume in the joint cavity. When the knee joint is inflamed or injured, the synovial membrane may experience pathological changes such as congestion and edema, leading to excessive secretion of synovial fluid or reduced absorption, causing symptoms such as joint swelling and pain.

▏Aging process of the knee joint

As we age, the knee joint, like the parts of a machine, gradually wears out and ages. This process is a complex, multi-factorial physiological and pathological process involving changes in the structure and function of each component of the knee joint.

1. Cartilage Degeneration The degeneration of articular cartilage is one of the most significant characteristics of knee aging. From a microscopic perspective, with age, the metabolic activity of chondrocytes gradually decreases, the ability to synthesize collagen and proteoglycans weakens, and at the same time, catabolism is relatively enhanced. This causes the collagen fibers in the cartilage to gradually become sparse and broken, the proteoglycan content decreases, water is lost, and the elasticity and compressive resistance of the cartilage decrease. Macroscopically, the surface of the articular cartilage begins to become uneven, with wear, cracking, and even exfoliation. These changes further destroy the normal structure and function of the articular cartilage, increase the friction between the joint surfaces, and weaken the cushioning effect, thereby causing symptoms such as knee pain, swelling, and limited mobility.

2. Meniscus injury The meniscus is under tremendous pressure and friction during long-term knee joint movement. With age, the texture of the meniscus gradually becomes brittle and its elasticity decreases. At the same time, the blood supply to the meniscus also decreases with age, which weakens the self-repair ability of the meniscus. In daily life, some slight twisting, flexion and extension movements may cause meniscus injury, such as meniscus tear. After the meniscus is injured, the knee joint will experience symptoms such as pain, snapping and jamming during movement, which seriously affects the normal function of the knee joint.

3. Ligament relaxation and injury As people age, the ligaments of the knee joint will also undergo a series of degenerative changes. The collagen fibers in the ligaments gradually decrease, while the elastic fibers increase, resulting in a decrease in the strength and elasticity of the ligaments and relaxation. Ligament relaxation reduces the stability of the knee joint, and the joint is prone to excessive displacement and shaking during movement, increasing the risk of injury to the articular cartilage and meniscus. In addition, due to decreased reaction ability and weakened muscle strength, the elderly are more likely to suffer ligament injuries such as anterior cruciate ligament rupture and medial collateral ligament injury when subjected to unexpected external forces, such as falls and sprains.

4. Synovial inflammation The aging synovial tissue of the knee joint is more sensitive to various stimuli and is prone to inflammatory reactions. Synovial inflammation can be caused by a variety of factors, such as debris produced by wear of articular cartilage, substances released after meniscus injury, and minor trauma in the joint. When synovial inflammation occurs, the synovium will become congested and edematous, secreting a large amount of synovial fluid, leading to swelling and pain in the knee joint. Long-term synovial inflammation may also cause synovial hyperplasia and hypertrophy, further aggravating the pain and limited movement of the knee joint.

▏Factors that affect knee joint aging

The aging process of the knee joint is not only determined by age, but also affected by a variety of internal and external factors. Understanding these factors will help us take targeted measures to delay the aging process of the knee joint.

1. Age Age is one of the most important factors leading to knee aging. As people age, the various components of the knee joint will undergo varying degrees of degenerative changes, which is an inevitable physiological process. Generally speaking, from around the age of 40, the cartilage of the knee joint begins to show obvious signs of degeneration, and the incidence of knee osteoarthritis in people over 50 years old increases significantly.

2. Weight: Being overweight is an important risk factor that accelerates the aging of the knee joint. The weight of the body is mainly transferred to the ground through the knee joint. The heavier the body weight, the greater the pressure on the knee joint. Long-term high pressure will accelerate the wear of articular cartilage and increase the risk of damage to structures such as the meniscus and ligaments. Studies have shown that for every 1 kg increase in body weight, the pressure on the knee joint when walking will increase by 3-4 kg. Therefore, maintaining a reasonable weight is of great significance to reducing the burden on the knee joint and delaying the aging of the knee joint.

3. Exercise method and intensity Moderate exercise is essential for maintaining the health of the knee joint, but improper exercise method and excessive exercise intensity may cause damage to the knee joint and accelerate its aging process. Long-term high-intensity weight-bearing exercise, such as long-term mountain climbing, climbing stairs, squatting, etc., will cause excessive pressure and friction on the knee joint, which can easily lead to wear of articular cartilage and meniscus damage. On the contrary, lack of exercise will cause muscle atrophy around the knee joint and decreased joint stability, which is also not conducive to the health of the knee joint. Therefore, it is very important to choose a suitable exercise method, such as walking, swimming, cycling and other low-impact exercises, and pay attention to controlling the intensity and time of exercise, in order to protect the knee joint.

4. Genetic factors Genetic factors also play a role in the aging process of the knee joint. Studies have found that certain gene polymorphisms are closely related to the risk of knee osteoarthritis. If there is a genetic history of knee joint disease in the family, the individual's risk of knee joint disease may be relatively increased. Although genetic factors cannot be changed, by understanding the family history and taking preventive measures in advance, such as maintaining a healthy lifestyle and regular knee joint examinations, the risk of disease can be reduced to a certain extent.

Strategies to protect your knee joint

Given the serious impact of knee aging on the quality of life of the elderly, it is particularly important to take active and effective measures to protect the knee joint. Comprehensive measures such as changing lifestyle, doing proper exercise and taking necessary medical interventions can slow down the aging process of the knee joint and alleviate the symptoms of knee joint diseases to a certain extent.

1. Maintain a healthy weight. Controlling weight is the primary measure to reduce the burden on the knee joint and protect it. By maintaining a healthy diet and exercising moderately, keeping your weight within a normal range can significantly reduce the pressure on the knee joint during daily activities. In terms of diet, you should follow the principle of a balanced diet, reduce the intake of high-calorie, high-fat and high-sugar foods, and increase the intake of vegetables, fruits, whole grains and high-quality protein. At the same time, appropriate aerobic exercise, such as brisk walking, running, swimming, etc., can help consume excess calories and achieve the goal of controlling weight.

2. Choose the right exercise method. Choosing an exercise method that has less impact on the knee joint and paying attention to the intensity and frequency of the exercise is the key to protecting the knee joint. Low-impact exercises such as walking, swimming, cycling, Tai Chi, etc. can not only strengthen the muscles around the knee joint, improve the stability of the joint, but also reduce the wear on the articular cartilage. Before exercising, be sure to do sufficient warm-up activities, such as joint activities and muscle stretching, to reduce the risk of sports injuries. During exercise, pay attention to maintaining the correct posture and avoid excessive fatigue. If you experience discomfort such as knee pain during exercise, you should stop exercising immediately and seek medical attention in time.

3. Strengthen the muscles around the knee joint. The muscles around the knee joint play an important role in maintaining joint stability and reducing joint pressure. Through targeted muscle training, muscle strength can be enhanced, the biomechanical environment of the joint can be improved, and the aging process of the knee joint can be delayed. Common exercise methods include quadriceps isometric contraction training, straight leg raising training, and wall squatting. Quadriceps isometric contraction training can be performed at any time and any place. The patient only needs to tighten the thigh muscles, hold for a few seconds, then relax, and repeat. Straight leg raising training is supine position, straighten the legs and raise them to a certain angle with the bed surface (such as 30°-60°), hold for a few seconds, then slowly lower them, alternating legs. When squatting against the wall, the patient stands with his back against the wall, his feet shoulder-width apart, and slowly squats down so that the knees do not exceed the toes and the thighs are parallel to the ground. After holding for a period of time, stand up and rest, and repeat. These exercise methods are simple and easy to do, suitable for the elderly to do at home.

4. Pay attention to daily posture and habits In daily life, maintaining good posture and correct movement habits is essential for protecting the knee joint. When standing, you should keep your chest and abdomen straight, avoid bending over and hunching your back and turning your knees inward or outward. When walking, keep a moderate pace and avoid rushing and running. When going up and down stairs, try to go slowly step by step, and use the power of the handrail to reduce the burden on the knee joint. Avoid sitting or standing for a long time, and get up and move around every once in a while to promote blood circulation in the knee joint. In addition, when lifting heavy objects, you should try to avoid bending over and lifting directly, but squat first, bring the object close to the body, and use the strength of the legs to slowly stand up to reduce the pressure on the knee joint. As you enter your golden years, rationally plan your exercise and pay attention to the protection of the knee joint, which can not only prolong your exercise life, but also improve your quality of life. Remember, scientific exercise combined with good habits is the best companion on the road to health. I hope that every middle-aged and elderly person can find happiness in exercise, have a pair of strong knee joints, and enjoy a healthy and energetic old age.

(Picture from the Internet)

Author | Han Mei is a practicing pharmacist who has worked in a well-known national tertiary hospital for more than 30 years and has rich medical care experience. She has represented the hospital on many occasions to go out for exchanges and study. She is an expert in food hygiene and nutrition, has a national nutritionist qualification, and is a science enthusiast.

Preliminary review | Chen Jiaqi, Li Shuhao

Review | Wei Xinghua

Final Review | Han Yonglin