In our daily lives, the knees bear a huge responsibility, not only to support our body weight, but also to ensure that we can run and jump.
However, when the knee suddenly goes limp, making it feel like it's out of support, many people may reflexively assume it's because of a calcium deficiency.
However, there is more to a weak knee than that, it can be a precursor to some more serious conditions.
The phenomenon of weak knees
For those young people who regularly engage in strenuous exercise, weak knees may be due to excessive fluid loss during exercise.
After a high-intensity workout, if hydration and electrolyte replenishment don't keep up, it can lead to a loss of knee support and a feeling of weakness in the legs. This is not uncommon, but it should be especially noticed in the summer or when participating in long periods of physical activity.
For middle-aged and elderly people, the causes of weak knees are even more complicated. As we age, the soft tissues around the knee may affect the normal function of the knee due to long-term wear and tear or painful irritation.
In addition, if there is tissue stuck inside the knee joint, such as fragments after a meniscus injury, it can also cause the knee to suddenly be unable to move normally, or even spasm, a condition known in medicine as a "joint snap".
Therefore, when you feel weak in your knees, don't simply blame it on calcium deficiency, especially for middle-aged and elderly people, it is particularly important to go to the hospital for a detailed examination in time.
X-rays, MRI and other imaging tests can help doctors accurately diagnose what is causing the knee discomfort, whether there is soft tissue damage or arthritis and other conditions.
Knee weakness and meniscus injury
Many people may not realize that there may be some serious diseases hidden behind the weak knee, such as meniscus injury.
It's not just a small problem with our joints, but it can seriously affect our mobility.
The meniscus are important structures in the knee joint, and they act like two crescent-shaped pieces of cartilage between the thigh bone and tibia, helping to distribute pressure in the knee joint, maintain stability during rotation, and lubricate the joint.
When the meniscus is damaged, it can occur due to strenuous exercise or long-term wear and tear, which can lead to knee pain, limited movement, and even weakness of the knee, and even walking in severe cases.
According to epidemiological data, meniscal injuries account for 12% to 14% of orthopedic injuries of the knee, with approximately 60 to 70 new meniscus injuries occurring per 100,000 people.
This type of injury can be divided into acute and chronic types: acute is usually caused by a one-off violent trauma, while chronic can be caused by natural aging or long-term repetitive stress.
More serious is a tear at the base of the meniscus, which can lead to significant functional limitations of the knee. If left untreated, the affected cartilage may degenerate rapidly and may eventually require total knee replacement surgery.
But fortunately, surgical repair of the meniscus root can significantly improve the patient's prognosis and delay the progression of osteoarthritis.
Diagnosing a meniscal injury usually requires a detailed history and physical examination, and if necessary, imaging tests such as MRI to determine the type and extent of the injury.
Treatment ranges from conservative methods such as rest, cold compresses, compression and elevation of the injured leg with physiotherapy and medication, to surgical treatment, usually arthroscopic surgery to repair or remove the meniscus.
In addition, it is important to prevent meniscus injuries. This includes avoiding repetitive knee overuse, maintaining an appropriate body weight, performing knee stability and strength training, and doing a proper warm-up before exercising.
For athletes who often need to run and jump, choosing the right sports shoes and using knee pads are also effective ways to prevent meniscus injuries.
Knee weakness and bony hyperplasia
A common cause of knee weakness is bone hyperplasia, commonly known as bone spurs, which is especially common in knee osteoarthritis.
This is not just a simple matter of age, but a complex situation involving degenerative joint changes that we need to take seriously.
Bone hyperplasia, which is actually the formation of extra bone tissue at the edges of the bones and joints.
This condition usually occurs when the joints are degenerative and degenerative with age or long-term joint overload, the articular cartilage gradually wears down and damages, and the underlying bones overgrow in an attempt to repair the damage, eventually forming bone growths.
This additional bone tissue may irritate the surrounding soft tissues, causing pain and inflammation, making the knee feel soft and even affecting walking in severe cases.
According to data from the Global Burden of Disease Study, the disease burden of knee osteoarthritis in China has increased significantly in recent decades, with both the number of cases and new cases steadily increasing.
This shows that hyperostosis and knee osteoarthritis are becoming an increasingly common problem that requires our close attention.
The effects of bone hyperplasia are not limited to the elderly population, young athletes and workers who have been engaged in heavy physical labor for a long time, and may also accelerate the degenerative process of articular cartilage due to joint overuse and repeated micro-trauma, resulting in bone hyperplasia.
Treating knee weakness caused by hyperostosis usually requires a comprehensive approach.
Conservative treatment includes medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) and painkillers, and physical therapy including heat, cold compresses, massage, and exercise therapy, all of which aim to strengthen the muscles around the joints and reduce the burden on the joints.
In addition, lifestyle modifications, such as weight loss, avoiding joint overuse, and moderate exercise, are essential.
In some severe cases, if conservative treatment is ineffective, surgery such as arthroscopic surgery may be needed to remove bone spurs from the joint and repair damaged cartilage. In more severe cases, knee replacement surgery may be required.
The key to preventing hyperostosis and related diseases is to maintain healthy joint function, which includes maintaining an appropriate weight, avoiding joint overload, performing regular joint function training, timely treatment of joint injuries and avoiding long-term joint inflammation.
Knee softness with synovitis
Synovitis is inflammation of a thin layer of tissue inside the knee joint called synovium. This synovial membrane is not only the lining of the joint, but also responsible for secreting the fluid that lubricates the joint.
When the synovium becomes inflamed, there may be an excessive buildup of joint fluid, causing the joints to swell and pain, symptoms that can most likely make your knee feel weak, as if it had suddenly lost its support.
Recent studies have found that synovitis may not only be an early sign of knee osteoarthritis, but may also affect the entire development of osteoarthritis.
This is because the synovium's own inflammatory response releases a series of inflammatory mediators and cytokines, which play a role in the development of the disease.
However, while we have some basic understanding of the effects of these inflammatory responses, a complete description of these pathological changes at the molecular level is still an unexplored area.
MRI has become an important tool for diagnosing synovitis. This noninvasive test can help doctors assess the thickness of the synovium and the extent of the lesion.
Studies have shown that synovial thickness in patients with advanced knee osteoarthritis is positively correlated with synovial pathological scores, which means that synovial thickness measured by MRI can be used as a basis for judging the degree of synovitis.
Further studies have also found that synovitis mediates the relationship between femoriotibial bone marrow lesion (BML) and knee pain to some extent, and the proportion of this mediating effect varies at different time points.
Patellomalacia and cerebral infarction
Malomalacia of the patella, a common knee condition especially in adolescents and athletes. The typical symptom of this condition is pain in the front of the knee, especially after activities such as prolonged standing, running, squatting, or climbing stairs.
The root cause of this pain is the deterioration of the cartilage on the back of the patella, causing the cartilage surface to become rough and no longer smooth, creating friction between the patella and femur.
If the "lubricant" inside your knees becomes not smooth enough, there will be a "rustling" grinding sound every time you move, which is certainly not a pleasant experience.
On the other hand, cerebral infarction, commonly known as stroke, occurs when a blood vessel in the brain is blocked or ruptured, resulting in damage to brain tissue.
Cerebral infarction can cause weakness or paralysis on one side of the body and, in severe cases, speech and cognitive function. During the recovery period of cerebral infarction, patients may experience sudden weakness of their knees when walking.
This weakness may be due to a cerebral infarction affecting the areas of the brain that control limb movement, resulting in decreased muscle strength, or muscle atrophy due to prolonged bed rest.
Whether it's patellar malacia or knee weakness due to cerebral infarction, they are a reminder that we need to be alert to these symptoms and seek appropriate treatment.
For chondromabia of the patella, treatment may include physical therapy, wearing appropriate knee braces, and possible surgical intervention.
For rehabilitation after cerebral infarction, comprehensive rehabilitation and appropriate physical therapy are needed to help restore muscle function and strength.
So, if you or someone around you is experiencing similar symptoms, don't ignore it, seek medical attention in time, take the right treatment measures, and get your life back on track as soon as possible.
References are as follows:
[1] Epidemiological investigation of 602 cases of knee meniscus injury
[2] Analysis of the current situation and trend of knee osteoarthritis disease burden in China based on GBD big data
[3] Association between bone marrow injury and knee pain in synovitis-mediated osteoarthritis: data from the National Institutes of Health (FNIH) Osteoarthritis Biomarker Alliance Foundation
[4] Pathogenesis and research progress of synovitis in patients with knee osteoarthritis
[5] Incidence and risk factors of symptomatic knee osteoarthritis in middle-aged and elderly China