Differential Diagnosis for 50-year-old Female with Bilateral Knee Pain

Single Most Likely Diagnosis

• Osteoarthritis (OA): This is the most common cause of knee pain in adults over 50, characterized by degenerative changes in the joint cartilage and underlying bone. The bilateral nature of the pain and the patient's age make OA a highly probable diagnosis.

Other Likely Diagnoses

• Rheumatoid Arthritis (RA): An autoimmune disorder that can cause pain, swelling, and stiffness in multiple joints, including the knees. Although less common than OA, RA is a significant consideration, especially if there are symptoms of morning stiffness or systemic symptoms.
• Meniscal Tears: Tears in the cartilage of the knee joint can cause pain, especially with twisting or bending movements. Given the duration of symptoms, chronic meniscal tears could be a contributing factor.
• Ligament Sprains: Injuries to the ligaments surrounding the knee can cause chronic pain if not properly healed or if there is ongoing instability.

Do Not Miss Diagnoses

• Septic Arthritis: Although less likely, an infection within the joint space is a medical emergency that requires prompt diagnosis and treatment to prevent permanent joint damage.
• Bone Tumors or Cysts: Rarely, knee pain can be the first symptom of a bone tumor or cyst. Early detection is crucial for effective treatment.
• Osteonecrosis: A condition where the bone tissue dies due to lack of blood supply, which can cause severe knee pain. It's essential to consider this diagnosis, especially if the patient has risk factors such as long-term steroid use.

Rare Diagnoses

• Gout or Pseudogout: These are forms of arthritis caused by the deposition of urate crystals (gout) or calcium pyrophosphate dihydrate crystals (pseudogout) within the joints. While they can cause acute, severe pain, chronic bilateral knee pain is less typical.
• Hemochromatosis: A genetic disorder leading to iron overload, which can cause arthritis, including knee pain, due to iron deposition in the joints.
• Sarcoidosis: A condition where inflammatory cells form lumps known as granulomas in various parts of the body, including the joints, leading to pain and stiffness.

Each of these diagnoses has a different set of implications for treatment and management, highlighting the importance of a thorough diagnostic evaluation.