Differential Diagnosis

• Single most likely diagnosis
  • Osteoarthritis (OA) of the DIP joint: This is the most likely diagnosis given the presence of mild degenerative changes in the DIP joint of the first digit. OA is a common condition characterized by wear and tear of the joint cartilage, leading to bone-on-bone contact and degenerative changes.
• Other Likely diagnoses
  • Trauma or injury to the DIP joint: Although there is no gross evidence of acute displaced fracture, a previous trauma or injury to the DIP joint could have led to the development of degenerative changes.
  • Psoriatic arthritis (PsA): PsA is a type of inflammatory arthritis that can cause degenerative changes in the joints, including the DIP joints. However, the absence of other characteristic features such as skin lesions or nail changes makes this diagnosis less likely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Septic arthritis: Although the soft tissue is grossly unremarkable, septic arthritis is a potentially life-threatening condition that requires prompt diagnosis and treatment. It is essential to consider this diagnosis, especially if there are any symptoms such as fever, redness, or swelling.
  • Osteonecrosis: Osteonecrosis, also known as avascular necrosis, is a condition where the bone tissue dies due to lack of blood supply. It can occur in any joint, including the DIP joint, and requires prompt diagnosis and treatment to prevent further damage.
• Rare diagnoses
  • Gout: Gout is a type of inflammatory arthritis that can cause degenerative changes in the joints, including the DIP joints. However, it is relatively rare in the DIP joints and usually affects the base of the big toe.
  • Hemochromatosis: Hemochromatosis is a genetic disorder that can cause iron overload, leading to degenerative changes in the joints, including the DIP joints. However, this diagnosis is rare and would require further testing to confirm.