When walking, your knees suddenly become weak. Is there something wrong with your legs? Experts answer...

In daily life, many people may have experienced such a situation:

A sudden "give-up" in your knees while you're walking, and you feel like you're going to fall, is common but can be confusing and worrying.

So, what exactly is going on when your knees suddenly become "soft"? Let's explore the possible reasons.

When walking

What happens to the knee joint?

First, we need to understand the basic structure and function of the knee joint.

The knee joint is one of the largest and most complex joints in the human body. It is composed of the femur, tibia and patella (also known as the kneecap). There are many ligaments, tendons and muscles around it to maintain its stability and flexibility. Different parts of the knee joint cooperate with each other to complete a variety of complex activities such as walking, running and jumping.

Here are some key parts of the knee joint that play a role in walking:

Femur : The thighbone that connects to the patella and tibia at the knee joint. As you walk, the distal end of the femur moves forward, pushing the knee joint into flexion and extension.

Patella (kneecap) : Located between the quadriceps tendon and the patellar tendon, it protects and lubricates the knee. As you walk, the patella moves up and down as the knee flexes and extends, helping to reduce friction and provide stability.

Tibia : The bone of the lower leg that forms the knee joint with the femur. The tibia moves forward and backward as the foot moves during walking, especially during heel strike and ball of foot strike.

Quadriceps: This is a group of muscles on the front of the thigh that includes the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. They are primarily responsible for extending the knee joint. During the stance phase of walking, the quadriceps muscles contract to help straighten the knee joint.

Hamstrings: A group of muscles located at the back of the thigh that includes the semitendinosus, semimembranosus, and biceps femoris. They are primarily responsible for flexing the knee joint. During the swing phase of walking, the hamstrings contract to help flex the knee joint and allow the foot to swing forward.

Patellar tendon: Connects the patella to the tibia and is an extension of the quadriceps muscle. As you walk, the patellar tendon tightens and relaxes as the knee extends and flexes, helping to propel the body forward.

Meniscus: Located in the knee joint, these are two C-shaped pieces of fibrous cartilage that provide cushioning and stability. When you walk, the menisci move with the knee joint to help disperse joint pressure.

Joint capsule and ligaments: The joint capsule and ligaments of the knee joint (such as the anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament, and lateral collateral ligament) play a stabilizing role when walking, preventing the joint from moving too much or being injured.

The knee suddenly becomes weak

Possible causes

1

Muscle fatigue

After standing or walking for a long time , especially without adequate rest, the muscles around the knee joint may fatigue, causing a momentary feeling of weakness. This condition usually improves after a short rest.

2

Ligament laxity or damage

The ligaments around the knee joint (such as the anterior cruciate ligament, posterior cruciate ligament, etc.) are responsible for maintaining the stability of the joint. If the ligaments are loose or injured, the knee joint may lose stability instantly, and a "soft" feeling may occur. Ligament injuries are common in athletes or people who engage in high-intensity physical labor.

3

Meniscus injury

The meniscus is a soft tissue structure in the knee joint that cushions and stabilizes the joint. If the meniscus is injured or torn, it may cause a sense of catching or weakness when the knee moves. Meniscus injuries are common in sports that involve sudden twisting of the knee joint, such as badminton, basketball, football, etc.

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4

Chondromalacia patella

Chondromalacia patellae refers to the degeneration and damage of the patellar cartilage, which is common in young athletes or people who engage in long-term weight-bearing activities at the knee joint. Patients may feel sudden weakness in the knee joint when walking or going up and down stairs. Chondromalacia patellae is related to factors such as knee joint degeneration, overuse of the knee joint, and knee joint trauma.

5

Neurological factors

The movement of the knee joint is controlled by the nervous system. If the nerves are compressed or damaged (such as lumbar disc herniation compressing the nerves), it may affect the movement of the knee joint, resulting in a sudden "soft" feeling. Lumbar disc herniation is common in people who sit for a long time or carry heavy loads for a long time.

6

arthritis

Chronic joint diseases such as osteoarthritis or rheumatoid arthritis can also cause a loss of stability in the knee joint, leading to temporary weakness. Osteoarthritis is more common in older people, while rheumatoid arthritis can occur at any age.

If your knees often feel "soft" when you walk, we should first consider meniscus injury and patellar softening.

How to deal with it

The knee suddenly becomes weak

1

Take adequate rest

If it is caused by muscle fatigue, it is recommended to take a proper rest and avoid standing or walking for a long time. Fatigue can be relieved by raising the legs, applying heat, etc.

2

Strengthen your exercise

Proper muscle strength training (such as quadriceps and hamstring exercises) can enhance knee stability and prevent the occurrence of weakness.

Common exercise methods include:

Squats: Helps strengthen the quadriceps and buttocks muscles. People with patellofemoral joint diseases should do this under the guidance of a doctor.

Straight Leg Raise Exercise: Enhance knee joint stability through leg strength training.

3

Wear knee pads

Knee braces can be worn for extra support and protection when doing strenuous exercise or walking for long periods of time. Knee braces can help stabilize the knee joint and reduce the risk of injury.

4

Maintain a healthy weight

Being overweight can put a strain on your knee joints, so maintaining a healthy weight can help reduce stress on your knee joints and prevent related problems. You can maintain your weight by eating a healthy diet and exercising regularly.

5

Pay attention to posture and movement

In daily life, paying attention to correct posture and movements can reduce the risk of knee injury. For example, avoid maintaining the same posture for a long time and avoid sudden and intense exercise.

6

Seek medical attention promptly

If your knee suddenly becomes weak frequently, or is accompanied by pain, swelling, or other symptoms, it is recommended that you seek medical attention immediately for a detailed examination and diagnosis. Your doctor may recommend imaging tests (such as X-rays, MRI, etc.) to determine the specific cause.

Protect your knees

You can do this

In order to better protect the knee joint, we can take the following measures:

1

Eat a healthy diet

The diet should contain rich protein, vitamins and minerals, especially calcium, vitamin D and collagen , which help maintain healthy bones and joints.

2

Exercise regularly

Moderate aerobic exercise (such as walking, swimming, cycling, etc.) can enhance cardiopulmonary function and improve joint flexibility and stability. At the same time, avoid excessive exercise, especially exercise that puts greater pressure on the knee joint.

3

Maintain good living habits

Quit smoking and limit alcohol consumption to avoid the impact of bad living habits on your health. Smoking and excessive drinking may affect the health of bones and joints.

4

Regular medical check-ups

Regular physical examinations, especially for people at risk of knee disease, can detect problems early and take timely measures.

5

Wear appropriate shoes

Wearing the right shoes can provide good support and cushioning, reducing the impact on the knee joint. Choose shoes with soft soles and good support, and avoid high heels and shoes with too hard soles.

In daily life, we should pay attention to the health care of knee joints and take active preventive measures to reduce the occurrence of knee joint diseases. Through scientific exercise, a reasonable diet and good living habits, we can effectively improve the health level of knee joints and enjoy a healthier and more fulfilling life.

Planning and production

Author: Ji Gang, deputy chief physician of orthopedics, First Hospital of Hebei Medical University

Review丨Jia Junxiu, deputy chief physician of orthopedics, Peking University Shougang Hospital

Wang Minghai Director of Orthopedics Department, Shanghai Fifth People's Hospital, Fudan University

Planning丨Yang Yaping

Editor: Yang Yaping

Proofread by Xu Lailinlin