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 on the outside of the knee.
- Other Likely diagnoses
- Lateral meniscal tear: A tear in the cartilage of the knee joint can cause pain on the outside of the knee, especially with twisting or bending movements.
- Lateral collateral ligament (LCL) sprain: A sprain of the LCL, which connects the femur to the fibula, can cause pain on the outside of the knee, especially with weight-bearing activities.
- Popliteus tendonitis: Inflammation of the popliteus tendon, which connects the popliteus muscle to the femur, can cause pain on the outside of the knee, especially with activities that involve twisting or bending.
- Do Not Miss diagnoses
- Osteonecrosis of the femoral condyle: A condition in which the bone tissue in the femoral condyle (the rounded end of the femur) dies due to lack of blood supply, which can cause severe pain on the outside of the knee.
- Stress fracture of the femur or fibula: A small crack in the bone can cause pain on the outside of the knee, especially with weight-bearing activities.
- Septic arthritis: A bacterial infection of the knee joint can cause severe pain, swelling, and redness, and requires prompt medical attention.
- Rare diagnoses
- Peroneal nerve compression: Compression of the peroneal nerve, which runs down the outside of the leg, can cause pain, numbness, and weakness on the outside of the knee.
- Ganglion cyst: A benign cyst that can form on the outside of the knee joint, which can cause pain and limited mobility.
- Osteochondroma: A type of benign bone tumor that can form on the outside of the knee joint, which can cause pain and limited mobility.