This is a randomized trial of benzoyl peroxide soap versus Hibiclens soap for surgical
preparation. The objective is to determine whether benzoyl peroxide soap, commonly available
in drug stores for over-the-counter acne treatment, is as or more effective than the standard
surgical preoperative soap, Hibiclens soap (chlorhexidine gluconate), in reducing loads of
Propionibacteria (Propi) on or under the skin of patients prior to shoulder arthroplasty
(joint replacement).