Knee pain can be divided into three major categories:
- Acute injury: such as a broken bone, torn ligament, or meniscal tear
- Medical conditions: arthritis, infections
- Chronic use/overuse conditions: osteoarthritis, patellar syndromes, tendinitis, and bursitis
Below is a list of some of the more frequent causes of knee pain. This is not an all-inclusive list but rather highlights a few causes of knee pain in each of the above categories.
Fractures: Direct trauma to the bony structure can cause one of the bones in the knee to break. This is usually a very obvious and painful injury. Most knee fractures are not only painful but will also interfere with the proper functioning of the knee (such as kneecap fracture) or make it very painful to bear weight (such as tibial plateau fracture). All fractures need immediate medical attention.
Ligament injuries: The most common injury is the ACL (anterior cruciate ligament) injury. This is often a sports-related injury due to a sudden stop and change in directions.
Meniscus injuries: The menisci (medial and lateral) are made of cartilage and act as shock absorbers between bones in the knee. Twisting the knee can injure the meniscus.
Dislocation: The knee joint can be dislocated, which is a medical emergency that requires immediate attention. Knee dislocation can compromise blood flow to the leg and have other related problems. This injury often occurs during a motor-vehicle accident when the knee hits the dashboard.