Why does my knee hurt and become immobile at night, but gets better after a while? What should I do?

Generally, knee pain at night that causes temporary immobility but resolves after a while may be caused by muscle fatigue, improper posture, local exposure to cold, meniscus injury, osteoarthritis, or other reasons. If discomfort persists, please seek medical attention promptly. Detailed explanations are as follows:

1. Muscle Fatigue

When muscles are fatigued, metabolic byproducts such as lactic acid accumulate in the muscle tissue, causing localized inflammatory reactions that stimulate nerve endings and result in pain. During nighttime rest, uneven muscle relaxation may lead to muscle tension or spasms, thereby causing pain. Applying heat can increase local muscle temperature, dilate blood vessels, promote blood circulation, accelerate the removal of metabolic byproducts, and relieve muscle fatigue.

2. Improper Posture

Poor sleeping posture, such as excessive pressure or bending of the knee, may also cause knee pain at night. Adjusting sleeping posture, using suitable pillows or pads to support the knee, and maintaining the knee joint in a natural position can help reduce pressure.

3. Loose Bodies in the Knee Joint

Loose bodies in the knee joint refer to free bone fragments or cartilage pieces within the joint cavity that can move freely. During nighttime rest, these loose bodies may become lodged in the joint space, causing severe pain. However, with slight joint movement, the loose bodies may shift to another location, relieving the pain. This condition may also be accompanied by symptoms such as joint locking and clicking, swelling, and joint effusion. Patients can use medications such as ibuprofen sustained-release capsules, diclofenac sodium sustained-release tablets, triamcinolone acetonide and neomycin plaster, among others, to alleviate pain, as advised by a physician.

4. Meniscus Injury

During nighttime rest, due to prolonged inactivity of the joint, the meniscus may become lodged in the joint space, causing severe pain. However, slight joint movement may relieve the impingement and reduce pain. Symptoms such as joint pain and swelling may occur. It is recommended to follow medical advice and use medications such as glucosamine sulfate capsules, tongluo qutong ointment, and cefixime granules for treatment.

5. Osteoarthritis

During nighttime rest, joints may become stiff due to prolonged inactivity, and pain may intensify upon sudden movement. However, as joint movement continues, local blood circulation improves, and the pain may subside. Symptoms such as joint pain and stiffness may also be present. Patients should follow medical advice and use medications such as ibuprofen tablets, celecoxib capsules, meloxicam capsules, and others for treatment.

In daily life, it is recommended to engage in moderate aerobic exercises such as walking and swimming to strengthen the muscles around the knee joint and improve stability.