Differential Diagnosis for Knee Tendinitis
Single Most Likely Diagnosis
- Patellar Tendinitis: This is the most common form of knee tendinitis, often affecting athletes who participate in sports that involve jumping, such as basketball and volleyball. The pain is typically localized to the front of the knee, just below the kneecap.
Other Likely Diagnoses
- Quadriceps Tendinitis: Inflammation of the quadriceps tendon, which connects the quadriceps muscle to the kneecap. This condition is common in individuals who participate in running or cycling.
- Iliotibial (IT) Band Tendinitis: Friction and inflammation of the iliotibial band, a ligament that runs down the outside of the thigh from the hip to the knee. This condition is common in long-distance runners.
- Pes Anserine Tendinitis: Inflammation of the tendons that insert into the pes anserine, a bony prominence on the lower inside part of the knee. This condition is more common in older, overweight individuals.
Do Not Miss Diagnoses
- Septic Arthritis: A bacterial infection within the knee joint, which can present with pain, swelling, and warmth. This condition requires prompt antibiotic treatment to prevent joint destruction.
- Osteonecrosis: Death of bone tissue due to a lack of blood supply, which can cause knee pain and should be considered in patients with risk factors such as long-term steroid use or excessive alcohol consumption.
- Tumor: Although rare, a tumor within or around the knee can cause pain and should be considered in the differential diagnosis, especially if the pain is persistent and not responding to typical treatments.
Rare Diagnoses
- Gout or Pseudogout: Deposition of urate or calcium pyrophosphate crystals within the knee joint, leading to acute inflammatory arthritis. These conditions can cause severe pain and should be considered in patients with a history of similar episodes or risk factors.
- Inflammatory Arthritis: Conditions such as rheumatoid arthritis or lupus can cause knee pain and should be considered in patients with systemic symptoms or a history of autoimmune disease.
- Bursitis: Inflammation of the fluid-filled sacs (bursae) that cushion the knee joint, which can cause pain and swelling. This condition can be caused by direct trauma, infection, or repetitive motion.