Why does total hip and knee replacement surgery often result in pneumonia?

 One of the most common complications after total hip or knee replacement surgery is pneumonia. This occurs in about 15-30% of patients, and the risk is highest in the first week after surgery.

There are several reasons why this might happen. First, the surgery can cause damage to the lungs, which makes it more difficult for them to fight off infection. Second, anesthesia and other medications used during surgery can suppress the immune system and make it more difficult for the body to fight infection. And finally, patients who are hospitalized after surgery are often at increased risk for developing pneumonia due to their weakened state and exposure to other patients with infections.