Propionibacterium acnes is a pathogen commonly identified in postoperative shoulder infections. A recent study has shown that P. acnes is likely to be disseminated in the operating field from the subcutaneous layer by the manipulation of soft tissues by the surgeon and the instruments. Disinfection of the subcutaneous tissue seems to significantly reduce contamination of the operating field during primary shoulder surgery. This study seeks to assess the efficacy of disinfection of the subcutaneous tissue compared to dissection with an electrosurgical unit on P. acnes contamination during primary shoulder surgery.

The investigators are going to study the efficacy of disinfecting the subcutaneous tissue with Betadine standard solution during primary shoulder surgery compared to electrosurgical dissection. They will randomize 105 patients on two arms. The control group receiving no disinfection of the subcutaneous tissue but a dissection with an electric cautery(A) and intervention group receiving a disinfection of the subcutaneous tissue (B). They believe that the duration of 4 years is sufficient to recruit the number of patients necessary for this study.

All patients 18 years of age or older admitted to Valais Hospital for primary shoulder surgery and having signed the consent of the study will be eligible.

The use of disinfection of the subcutaneous tissue during primary shoulder surgery could reduce contamination of the operating field and theoretically the post-operative infection rate after primary shoulder surgery.

The study focuses on disinfection with Betadine solution of the subcutaneous tissue during primary shoulder surgery. This action could decrease contamination of the operating field and the infection rate after primary shoulder surgery.

This solution is already widely used for disinfecting the skin and traumatic or surgical wounds.

The investigators will use it according to the recommendations made in the Swiss Compendium of Medicines.

No evidence has been brought to a decrease in this contamination if the dissection is carried out with an electric cautery. Scalpel dissection is used as standard in orthopedic surgery as well as in other surgical disciplines.

Inclusion Criteria:

1. = or> 18 years old
2. treated at the Valais Hospital for primary shoulder surgery.
3. have signed the consent

Exclusion Criteria:

1. <18 years old
2. History of shoulder surgery
3. History of shoulder infection
4. Antibiotic therapy in the 2 weeks preceding the intervention
5. Cortisone infiltration in the 6 months preceding the intervention
6. Allergy to iodinated contrast agent or Cefuroxime
7. Allergy to povidone iodine complex or other contraadication to Betadine
8. Refusal of study terms

A standard block randomization strategy will be used. The ratio between intervention and control will be set at 2: 1. This will facilitate recruitment and provide more information on the effectiveness of the intervention. The randomization sequence will be created using the STATA program.