Differential Diagnosis for Lateral Knee Pain
Single Most Likely Diagnosis
- Iliotibial (IT) Band Syndrome: This condition is characterized by inflammation of the iliotibial band, a ligament that runs down the outside of the thigh from the hip to the knee. IT band syndrome is a common cause of lateral knee pain, especially in runners or cyclists, and is worse after periods of inactivity, such as sitting, improving with activity as the band warms up.
Other Likely Diagnoses
- Lateral Meniscus Tear: Tears in the lateral meniscus can cause pain on the outside of the knee. Symptoms can include pain that worsens with twisting or bending and may improve with activity as the joint loosens.
- Lateral Collateral Ligament (LCL) Sprain: An injury to the LCL, which connects the femur to the fibula, can cause lateral knee pain. The pain might be exacerbated by activities that put stress on the outside of the knee and could potentially improve with movement as the surrounding muscles provide additional support.
- Popliteus Tendinitis: Inflammation of the popliteus tendon, which helps to rotate the knee, can cause lateral knee pain. This condition might improve with activity as the tendon and surrounding tissues warm up.
Do Not Miss Diagnoses
- Osteonecrosis of the Femoral Condyle: A condition where the bone tissue dies due to lack of blood supply. It can cause severe pain, especially after periods of rest, and is critical to diagnose early to prevent further bone collapse.
- Tumor: Although rare, a tumor in the lateral aspect of the knee could cause pain that might seem to improve with activity due to increased blood flow and warmth. It's essential to consider this possibility to ensure timely diagnosis and treatment.
Rare Diagnoses
- Peroneal Nerve Compression: Compression of the peroneal nerve as it wraps around the lateral aspect of the knee can cause pain, numbness, and weakness. This condition might improve with activity as the nerve is less compressed with certain movements.
- Ganglion Cyst: A benign lump that can develop on the outside of the knee, potentially causing pain, especially if it compresses nearby nerves or tendons. The pain might seem to improve with activity due to changes in pressure and position of the cyst.