Knee pain can be caused by various factors, including injuries, mechanical problems, types of arthritis, and other medical conditions. However, knee pain can also occur without a preceding injury. Here are some possible causes of knee pain without injury:

• Tendinitis: Tendinitis occurs when tendons, the tissues that join muscles to the bones, become inflamed. It is a common cause of knee pain without injury, with a dull ache in the joint. Resting can alleviate the discomfort resulting from tendinitis, but medical intervention is necessary for severe cases.

• Bakers Cyst: Another common reason behind sudden knee pain without injury is Bakers cyst, which refers to a fluid-filled swelling that occurs at the back of the knee. You might feel restriction in movements due to the swollen area, a possible sign of an undiagnosed knee injury. Also known as a popliteal cyst, it generally goes away on its own. In some cases, fluid drainage from the cyst is necessary for treatment.

• Osteoarthritis: Osteoarthritis occurs when inflammation and swelling of the knee joint cause discomfort. Deterioration of the knee might be responsible for this condition, and poor posture, obesity, or past injury are some factors that could contribute to it.

• Rheumatoid arthritis: This autoimmune disease is similar to osteoarthritis, but is often not localized to a single joint, and is indicated by stiffness, swelling, and pain.

• Bursitis: Bursitis is a painful condition that occurs when tiny sacs of fluid cushioning the bones in the knee joint become infected or irritated, leading to inflammation.

Most knee pain thats not related to a direct injury involves the connective tissues (ligaments and tendons) or cartilage. If you experience knee pain without injury, it is important to seek medical attention to determine the underlying cause and receive proper treatment.