What causes weak and shaky knees?

　　The knee may refer to the knee joint.Weakness or instability in the knee joint may be caused by factors such as overexertion, lack of exercise, knee arthritis, meniscus injury, or chondromalacia patellae. It is recommended to seek medical attention promptly, identify the underlying cause, and receive symptomatic treatment under the guidance of a qualified physician. Specific analyses are as follows:

　　1. Overexertion: Engaging in prolonged running, jumping, or similar activities may lead to fatigue of the muscles surrounding the knee joint, resulting in feelings of weakness or instability. It is recommended to reasonably regulate exercise intensity and allow adequate rest and recovery training, which can help improve these symptoms.

　　2. Lack of Exercise: Long-term inactivity of the lower limb muscles may lead to reduced muscle strength, decreasing the stability of the knee joint and causing sensations of weakness or instability. It is recommended to strengthen lower limb muscles through exercises such as squats and leg lifts, which can enhance knee joint stability and alleviate the aforementioned symptoms.

　　3. Knee Arthritis: This condition may be associated with excessive use of the knee joint or traumatic injuries. Common symptoms include joint pain, swelling, and restricted movement. Local inflammation may lead to cartilage wear, impairing normal joint function and causing the symptoms described above. Patients are advised to follow medical instructions for treatment with medications such as celecoxib capsules, glucosamine sulfate tablets, and diclofenac sodium gel.

　　4. Meniscus Injury: The meniscus is fibrocartilaginous tissue within the knee joint. When damaged, it may reduce joint stability and lead to symptoms of knee weakness or instability. Patients should follow medical advice for treatment with medications such as glucosamine sulfate capsules, Shujin Huoxue tablets (a traditional Chinese medicine), and amoxicillin capsules.

　　5. Chondromalacia Patellae: This condition primarily results from chronic damage to the articular cartilage on the underside of the patella, leading to changes such as swelling and fissuring of the cartilage. Main symptoms include knee pain and weakness, sometimes accompanied by grinding sounds during movement. Patients are advised to take medications such as glucosamine hydrochloride capsules, alendronate sodium tablets, and Zhuanggu Guanjie pills under a doctor’s supervision to improve symptoms.

　　In daily life, patients are advised to maintain a light diet, avoid spicy foods such as chili peppers and Sichuan pepper, ensure sufficient sleep, and perform gentle massage on the affected area, all of which may help relieve discomfort.