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 knee can cause pain on the lateral (outer) side of the knee, especially with twisting or bending movements.
- Lateral collateral ligament (LCL) sprain: The LCL is a ligament that connects the femur (thigh bone) to the fibula (outer lower leg bone). A sprain of this ligament can cause pain on the lateral side of the knee.
- Popliteus tendonitis: The popliteus tendon is a small tendon that connects the popliteus muscle to the lateral meniscus. Inflammation of this tendon can cause lateral knee pain.
- Do Not Miss diagnoses
- Osteonecrosis of the femoral condyle: This is a condition where the bone tissue in the femoral condyle (the rounded end of the femur) dies due to lack of blood supply. It can cause severe pain and should not be missed.
- Stress fracture: A stress fracture is a small crack in the bone that can cause pain, especially with weight-bearing activities. It is essential to diagnose and treat stress fractures promptly to avoid further complications.
- Septic arthritis: This is a bacterial infection of the joint that can cause severe pain, swelling, and redness. It is a medical emergency that requires prompt treatment.
- Rare diagnoses
- Peroneal nerve compression: The peroneal nerve runs down the outside of the knee and can be compressed, causing pain, numbness, and weakness in the foot and ankle.
- Ganglion cyst: A ganglion cyst is a benign lump that can form on the lateral side of the knee, causing pain and stiffness.
- Osteochondritis dissecans: This is a condition where a piece of cartilage and bone in the knee joint becomes damaged, causing pain and locking of the knee.