The study hypotheses will be tested using a prospective randomized-controlled trial of the effect of combination blue spectrum phototherapy and benzoyl peroxide on P. acnes at the shoulder arthroplasty surgical site. Accordingly, it will conform to the CONSORT (Consolidated Standards of Reporting Trials) guidelines. Subjects presenting to our Orthopaedic department will be randomized to one of three study arms:
1. Control: standard preparation of the surgical site without P. acnes pretreatment
2. BPO group: Pretreatment with 2 days of washes prior to surgery
3. BPO and Phototherapy: 2 days of washes with 3 treatments of blue spectrum phototherapy
Patients will be seen at our office will be consented and recruited into the study. Subjects will have standard of care evaluation including: radiographs, preoperative labs and clearances. If selected and agreeable, treatment with phototherapy will involve the application of three sessions lasting 3 minutes preoperatively; the sessions will be conducted by the patient at home for two days prior to surgery and in the preoperative holding area. During each application, protective eyewear will be used. For patients in the BPO groups, a 10% benzoyl peroxide wash will be used globally on the operative shoulder and axilla during showering. An educational leaflet will outline the surgical field in addition to temporary demarcation at the time of BPO pickup at the office. Additional tests, imaging or procedures will be at the discretion of the treating physician and documented during the study. During the postoperative visit at 10-14 days, the post operative wound will be assessed in the standard manner. Final culture results will be recorded for each patient and documented in the study database.
* The surgical site will be prepared in usual fashion with Chloroprep and the patients will receive preoperative Cefazolin (or vancomycin based on penicillin allergy)
* Following both draping and skin incision, the surgeons gloves will be changed; any blades used in the skin incision will also be discarded
* Intraoperative cultures will be taken following established protocols, published in the literature: an excisional biopsy 1cm long and 3mm wide will be taken from the medial wound edge at the time of incision; the superficial dermal tissue will be swabbed immediately after the biopsy is taken and finally, a swab of the glenohumeral (shoulder) joint will be performed prior to closure at the end of the procedure and after insertion of the implant.
* Specimens will be transported to the laboratory adjoining the operating room at our institution within 1 hour of harvesting and processed by microbiology technicians in a laminar flow biological safety hood. Tissue from the skin edge will be homogenized in sterile saline solution and plated on media: blood agar, chocolate agar, Brucella agar, MacConkey agar, Columbia nalidixic acid agar and phenylethyl alcohol anaerobic blood agar. All media will be incubated at 37C for 14 days.
* Specimens will be incubated for 14 days in aerobic and anaerobic media to detect P acnes and other organisms
* Culture results will not be discussed with patients; patients will be consented to not know their results as they are not clinically significant
* Prophylactic antibiotic treatment of positive cultures will not be performed in any case.
