Which of the following is a risk factor for pulmonary embolism that involves joint replacement?

• A. Hip or total knee implant
• B. Obesity
• C. History of stroke
• D. Acute respiratory disease

Answer: (A)

The key idea is that orthopedic surgery, especially hip or knee joint replacement, markedly raises the risk of pulmonary embolism. After such surgeries, people are prone to deep vein thrombosis in the legs because of three factors: blood becomes prone to clotting (hypercoagulable state) after surgery, leg movement is reduced (venous stasis), and the blood vessels may be injured during the procedure (endothelial injury). A clot that forms in the leg can dislodge and travel to the lungs, causing a pulmonary embolism.

Other options are less specific to joint replacement. Obesity is a general risk factor for clots, but it isn’t tied to the context of a joint replacement itself. A history of stroke also raises overall risk due to possible immobility, but again isn’t the procedure-related risk we’re focusing on. Acute respiratory disease isn’t a risk factor for developing a pulmonary embolism in the surgical context.

So, hip or total knee implant best describes the risk factor related to joint replacement.