Differential Diagnosis for Medial Tibiofemoral and Patellofemoral Pain with Moderate Lateral Tibiofemoral Involvement

• Single Most Likely Diagnosis
  • Osteoarthritis (OA) of the knee: This is the most likely diagnosis given the involvement of multiple compartments of the knee (medial tibiofemoral, patellofemoral, and moderate lateral tibiofemoral). OA is a degenerative joint disease that commonly affects these areas, especially in older adults.
• Other Likely Diagnoses
  • Meniscal tears: Tears in the menisci, which are cartilage structures in the knee joint, can cause pain in the medial and lateral tibiofemoral compartments. The presence of moderate lateral involvement suggests a possible meniscal tear.
  • Ligament sprains: Sprains of the medial or lateral collateral ligaments can cause pain and instability in the knee, potentially involving multiple compartments.
  • Patellofemoral pain syndrome (PFPS): Although PFPS primarily affects the patellofemoral joint, it can sometimes be associated with pain in other compartments due to altered biomechanics and tracking of the patella.
• Do Not Miss Diagnoses
  • Septic arthritis: An infection within the knee joint can cause severe pain, swelling, and warmth. It is crucial to consider this diagnosis, especially if there are systemic symptoms like fever or if the patient is immunocompromised.
  • Osteonecrosis: Also known as avascular necrosis, this condition involves the death of bone tissue due to a lack of blood supply. It can occur in any part of the knee and is a critical diagnosis not to miss due to its potential for rapid progression and severe consequences.
  • Tumor: Although rare, a tumor (benign or malignant) in the knee can cause pain and should be considered, especially if the pain is persistent, worsening, or accompanied by other systemic symptoms.
• Rare Diagnoses
  • Pigmented villonodular synovitis (PVNS): A rare condition characterized by the overgrowth of the synovial tissue in the joint, leading to pain, swelling, and potentially joint destruction.
  • Synovial chondromatosis: A condition where cartilage grows in the synovium, causing joint pain and swelling. It is rare and can be associated with loose bodies within the joint.
  • Neuropathic pain: Rarely, pain in the knee can be referred from a neuropathic source, such as a lumbar radiculopathy or peripheral neuropathy, and should be considered if other diagnoses are ruled out.