Infections on joint replacements remain one of the most serious complications of orthopaedic surgery. Despite improvements in skin preparation and antibiotic prophylaxis procedures, the risk of infection of joint prosthesis is still high, particularly for shoulder prostheses, especially in men. One of the bacteria most often involved in post-operative infections for shoulder prosthesis is Cutibacterium acnes (CA). This bacterium is one of the predominant bacteria in pilosebaceous units. Eradication of this micro-organism remains difficult despite the techniques used in the preoperative phase.

The objective of this protocol is to evaluate the efficacy of applying a 5% benzoyl peroxide topical during the 5 days preceding the procedure in the surgical skin incision area, which is based on local acne treatment, on the reduction of the CA bacterial load in the dermis of the approach to shoulder arthroplasty in men.

Inclusion Criteria:

• Male patients, Adult patients,
• Patient without a history of surgical intervention on the operated shoulder,
• Patient managed for glenohumeral, partial (cup or anatomical hemi- arthroplasty) or total (anatomical or inverted) glenohumeral arthroplasty placement for primary osteoarthritis, or secondary to necrosis, massive rotator cuff tear or old fracture.
• Patients affiliated to a social security system
• Patients who have given their informed and written consent

Exclusion Criteria:

• Patient with arthroplasty for resumption of previous shoulder surgery or failure of arthroplasty
• Patient with arthroplasty for acute trauma
• Patient on immunosuppressantsimmunosuppressive drugs
• Patient with inflammatory rheumatism
• Patient with progressive cancer pathology
• Allergies or intolerances concerning the modalities of selected skin preparations (Povidone Iodine, hypersensitivity to benzoyl peroxide)
• Dermatological pathologies in the area to be treated
• Acne treatment in the area to be treated within four weeks before inclusion
• Patient without possible help from a third party for the application of Cutacnyl® 5% in the intervention group if necessary
• Major under guardianship
• Patient under the protection of justice
• Patient not covered by social security