Differential Diagnosis for Non-Traumatic Knee Pain
Single Most Likely Diagnosis
- Osteoarthritis: This is the most common cause of non-traumatic knee pain, especially in older adults. It is characterized by wear and tear of the joint cartilage, leading to pain, stiffness, and limited mobility.
Other Likely Diagnoses
- Meniscal tear: A tear in the meniscus, a cartilage structure in the knee joint, can cause pain, swelling, and instability.
- Ligament sprain: A sprain in one of the knee ligaments, such as the medial or lateral collateral ligament, can cause pain, swelling, and instability.
- Tendinitis: Inflammation of the tendons surrounding the knee joint, such as the quadriceps or patellar tendon, can cause pain and stiffness.
- Bursitis: Inflammation of the fluid-filled sacs (bursae) that cushion the knee joint can cause pain, swelling, and limited mobility.
- Patellofemoral pain syndrome: Pain in the front of the knee, usually associated with activities that put stress on the knee, such as climbing stairs or squatting.
Do Not Miss Diagnoses
- Septic arthritis: A bacterial infection in the knee joint can cause severe pain, swelling, and limited mobility, and can lead to serious complications if not treated promptly.
- Crystal arthropathy (gout or pseudogout): A buildup of crystals in the joint can cause sudden, severe pain and swelling, and can be mistaken for other conditions.
- Tumor or cancer: A tumor or cancer in the knee joint or surrounding bone can cause pain, swelling, and limited mobility, and can be life-threatening if not diagnosed and treated promptly.
- Inflammatory arthritis (rheumatoid arthritis, lupus, etc.): Autoimmune disorders that cause inflammation in the joint can lead to serious complications if not diagnosed and treated promptly.
Rare Diagnoses
- Osteonecrosis: A condition in which the bone tissue dies due to lack of blood supply, can cause pain and limited mobility in the knee.
- Pigmented villonodular synovitis: A rare condition in which the synovial tissue in the joint becomes inflamed and forms tumors, can cause pain, swelling, and limited mobility.
- Hemophilia: A genetic disorder that affects the blood's ability to clot, can cause bleeding into the joint and lead to pain, swelling, and limited mobility.
- Neuropathic pain: Pain caused by nerve damage or compression, can cause burning, tingling, or numbness in the knee.