Scientifically protect the knee joint and effectively prevent knee joint injuries

Author: Yuan Feng, Chief Physician, Shanghai Sixth People's Hospital

Qiu Yongjia Chief Technician, Shanghai Sixth People's Hospital

Zuo Lili, Head Nurse, Shanghai Sixth People's Hospital

Reviewer: Zhao Jinzhong, Chief Physician, Shanghai Sixth People's Hospital

Many people do not pay attention to protection during physical exercise, which can easily lead to joint injuries. Lack of knowledge about joint protection has caused them to pay a heavy price. For joint injuries, prevention is the key. The knee joint is the most complex joint in the human body and is often injured during exercise. So, how can you protect your knee joint during daily exercise?

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1. Composition and load-bearing of the knee joint

The human knee joint is mainly composed of the distal femur, proximal tibia and patella, which contains the soft tissue joint capsule, meniscus, synovium and ligament groups including the anterior cruciate ligament, posterior cruciate ligament, medial ligament and lateral ligament.

All weight-bearing activities put stress on the knee joint. Usually, the stress on the knee joint is as follows:

1. The load on the knee joint is almost zero when lying flat

2. The weight on the knee joint when standing and walking is about 1 to 2 times the body weight

3. When going up and down slopes or stairs, the load on the knee joint is about 3 to 4 times the body weight.

4. The load on the knee joint when running is about 4 times the body weight

5. The weight on the knee joint when playing basketball and making layups is about 6 times the body weight

6. The weight on the knee joint when squatting or kneeling is about 8 times the body weight

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2. Common actions that injure the knee joint

1. Deep squats During the squat process, due to the squeezing of the posterior side of the knee joint and the poor mobility of the posterior horn of the medial meniscus, the posterior horn of the medial meniscus is easily squeezed and damaged, causing wear of the knee joint.

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2. Going up and down stairs or climbing mountains Going up and down stairs or climbing mountains can easily cause wear and tear on the patellofemoral joint. Twisting of the knee joint can also easily lead to meniscus damage or other soft tissue damage such as ligaments.

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3. Half-squat rotation in Tai Chi Half-squat rotation in Tai Chi not only causes severe wear and tear on the patellofemoral joint, but also easily causes meniscus damage. Therefore, it is not recommended for middle-aged and elderly people to do this kind of movement.

4. Rapid twisting movements during football, basketball, table tennis, and badminton can easily lead to knee joint injuries. Since the knee joints of middle-aged and elderly people already have degenerative changes and partial meniscus degeneration, the above movements can aggravate joint degeneration and cause meniscus damage.

5. Resistance knee extension. In the gym, there are professional equipment for resistance knee extension exercises. However, such movements can easily cause accelerated wear of the patellofemoral joint. Therefore, such exercises are not recommended for middle-aged and elderly people with patellofemoral joint degeneration.

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6. Sitting for a long time When sitting for a long time, the knee joint is in a flexed state for a long time, which is not conducive to the blood circulation of the lower limbs and easily causes swelling. For middle-aged and elderly patients with osteoarthritis, it is easy to cause the disease to worsen and the knee joint to become stiff.

Recommended Exercises

1. Swimming effectively exercises cardiopulmonary function, fully trains muscles throughout the body without bearing weight, and is very beneficial for protecting joints.

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2. Non-weight-bearing knee flexion and extension exercises: Sit on a chair with your feet in the air and perform free flexion and extension exercises on the knee joint. This exercise is non-weight-bearing and does not cause any damage to the knee joint. It can enhance the activity of the knee joint and plays a certain role in preventing osteoarthritis.

3. Moderate jogging ① When running, it is best to land with the front half of the sole of the foot first to cushion the vibration of the leg and prevent knee joint injury; ② The speed should be appropriate so that you do not feel short of breath and can talk to others while running. After running, it is not advisable to stop immediately, but to walk slowly or step on the spot to allow the organs of the human body to gradually recover from the state of exercise to the state of calm.

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4. Walking ① Lift and put down your legs slowly to avoid collision of the knee joint bones and aggravate the injury; ② The pace can be controlled within 60 steps per minute, and slow walking should be performed for 20 to 30 minutes every day; ③ The exercise time is about 30 minutes a day, and the exercise intensity should be such that you do not feel shortness of breath when walking, and your muscles feel mild soreness, and you can exercise after rest. The range of motion of the knee is not large, and the joint is under less force, which effectively reduces the impact and wear of the joint surface.

Note: The exercise principles are "gradual progress, focus on balance, and perseverance."

4. Do I need to wear knee pads in my daily life or during exercise? How should I choose knee pads?

1. Do I need to wear knee pads in my daily life or during exercise?

——Is it necessary to wear knee pads in daily life? If there is no problem or discomfort in the knee joint, there is no need to wear knee pads. Of course, for people who exercise, such as those who are overweight and want to lose weight through exercise, it is recommended to wear knee pads.

——Is there a requirement for the time to wear the knee brace? Generally, it is not recommended to wear the knee brace for 24 hours. Wearing it for too long may cause muscle atrophy. You can wear it for 1 to 2 hours and take a break. However, for patients with fracture immobilization or surgery, the wearing time should be carried out according to the doctor's requirements.

2. Types of knee pads and suitable groups

The first category is braking knee braces, which are mainly suitable for people with knee pain or sprains, ligament injuries, fractures around the knee undergoing conservative treatment or arthroscopic surgery, and fracture surgery.

The second category is the warm and health-care knee pads. They include heating knee pads and some ordinary towel knee pads. This type of knee pad is mainly suitable for cold knee joints, such as the old cold legs of the middle-aged and elderly, and long-term exposure to cold wind, etc., which can keep the knee joints warm.

The third category is sports knee pads. They include ordinary knee pads to prevent injuries after falling during sports, and protective knee pads with spring support. They are especially suitable for athletes with excessive weight, as well as those with knee pain, patellofemoral arthritis and other knee discomfort. This type of knee pad not only has an effective cushioning effect on the knee joint, but also has appropriate restrictions on the range of motion of the patella, which can reduce friction in the patellofemoral joint.

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Funded Projects:

1.Shanghai Xuhui District Science Popularization Innovation Project (xhkp-HM-2024009)

2. Shanghai Health Science Popularization Youth Talent Capacity Enhancement Project (JKKPYC-2024-B06)

3. "City Six-Lingang" Close-knit Health Consortium Science Popularization Project (JKLHT002)