Differential Diagnosis for Lateral Knee Pain
- Single most likely diagnosis
- Iliotibial (IT) band syndrome: This is the most common cause of lateral knee pain, especially in runners and cyclists. The IT band is a ligament that runs down the outside of the thigh from the hip to the knee, and friction or inflammation of this band can cause pain.
- Other Likely diagnoses
- Lateral meniscal tear: A tear in the cartilage of the lateral compartment of the knee can cause pain on the outside of the knee.
- Lateral collateral ligament (LCL) sprain: An injury to the LCL, which connects the femur to the fibula, can cause lateral knee pain.
- Popliteus tendonitis: Inflammation of the popliteus tendon, which connects the popliteus muscle to the femur, can cause pain on the outside of the knee.
- Peroneal tendonitis: Inflammation of the peroneal tendons, which connect the peroneal muscles to the fibula, can cause pain on the outside of the knee.
- Do Not Miss diagnoses
- Osteonecrosis of the femoral condyle: A condition where the bone tissue in the femoral condyle dies due to lack of blood supply, which can cause severe pain and disability if left untreated.
- Stress fracture of the fibula: A small crack in the fibula bone can cause pain on the outside of the knee, and if left untreated, can lead to a complete fracture.
- Septic arthritis: A bacterial infection of the joint can cause severe pain, swelling, and redness, and requires prompt antibiotic treatment to prevent long-term damage.
- Rare diagnoses
- Pigmented villonodular synovitis (PVNS): A rare condition where the synovial tissue in the joint becomes inflamed and forms tumors, which can cause pain and swelling.
- Synovial chondromatosis: A rare condition where cartilage grows in the synovial tissue of the joint, which can cause pain and swelling.
- Ganglion cyst: A rare condition where a fluid-filled cyst forms on the outside of the joint, which can cause pain and swelling.