The perioperative management of protein S deficiency in total hip arthroplasty.

: Protein S is an antithrombotic plasma protein that serves as a cofactor for another plasma protein, activated protein C. Patients who express a deficiency of protein S have an increased propensity to experience thromboembolic events. These events are often precipitated by factors that may cause thrombosis in nondeficient individuals, particularly in cases of trauma, pregnancy, or surgery. Anticoagulation therapy was instituted in a 45-year-old woman with known protein S deficiency and bilateral total hip arthroplasties.