UW Shoulder and Elbow Academy: Propionibacterium (P Acnes) in a shoulder arthroplasty

Seven years ago a man in his mid 60s presented with arthritis of his right shoulder

He elected to have a ream and run procedure. Cefazolin was administered preoperatively and discontinued after 24 hours.

He had excellent return of comfort and function until 18 months after his surgery when he noted discomfort around the insertion of the deltoid in the humerus. His pain was on use of the arm and not at rest. The pain ran down the lateral arm to the area of tip of the prosthesis. His range of motion and strength are excellent. His x-rays showed excellent glenoid healing and no evidence of subsidence. There was a very small lucent zone at the tip of his prosthesis. His lab tests were unremarkable.

We preformed a revision arthroplasty with a single-stage exchange and the red protocol (see this link). Going in to surgery, we thought we were dealing with 'aseptic' loosening of the stem. However , pathology revealed a humeral membrane with greater than 5 neutrophils in at least 5 high-powered fields, with chronic inflammation and focal foreign body giant cell reaction, and another humeral membrane that showed fibrinous tissue with chronic inflammation, but only rare neutrophils. Two synovial fluid specimens were sent for analysis, including the initial fluid specimen with 15,050 white blood cells (83% neutrophils,) and 3440 red cells. The culture results were: fluid: one colony Propi, humeral membrane 1+ Propi, stem explant 1+ Propi, and head explant 1+ Propi. After thorough debridement, a new prosthesis was inserted with Vancomycin soaked allograft.

After 5 weeks of intravenous vancomycin and oral rifampin, the antibiotics were discontinued because of neutropenia from which he recovered completely.

Recently we saw him back five years after his single stage revision. He had full function and no discomfort in his right shoulder.