Differential Diagnosis for Knee Swelling with Positive Homan's Sign and Calf Swelling

• Single most likely diagnosis:
  • a) DVT (Deep Vein Thrombosis): The patient presents with a positive Homan's sign, which is a clinical test used to detect DVT, although it is not highly specific. The combination of knee swelling, calf swelling, and the ability to move the ankle with mild discomfort 12 hours pre-operatively for arthroscopic surgery suggests a venous thrombosis. DVT is a common concern in patients undergoing surgery, especially those with recent immobility or trauma.
• Other Likely diagnoses:
  • d) Rupture of swelling with fluid extravasation in the posterior leg compartment: This could potentially cause calf swelling and discomfort, especially if there was a recent injury or procedure that led to fluid accumulation in the soft tissues. However, the presence of a positive Homan's sign leans more towards a vascular issue like DVT.
• Do Not Miss diagnoses:
  • b) Vascular occlusion: Although less likely given the patient's ability to move their ankle, a vascular occlusion could present with swelling and a positive Homan's sign. Missing this diagnosis could lead to severe consequences, including limb loss.
  • c) Compartment syndrome in the thigh: While compartment syndrome typically presents with the 5 Ps (pain, pallor, pulselessness, paresthesia, and paralysis), early stages might only show mild symptoms. It's crucial not to miss this diagnosis as it requires urgent intervention to prevent long-term damage.
• Rare diagnoses:
  • Other rare vascular or rheumatologic conditions could potentially present with similar symptoms but are less likely given the context. These might include conditions like phlegmasia cerulea dolens (a severe form of DVT) or specific types of vasculitis, but these would be uncommon and typically associated with additional systemic symptoms or findings.