Periprosthetic shoulder arthroplasty infections present in two different ways.
The first is the Obvious presentation as in this example of a 60 year old man with a prior revision left total shoulder that had been asymptomatic for 7 years.
Months prior to presentation he had a MSSA (Methicillin sensitive staph aureus) infection of his knee treated with a washout and IV antibiotics with complete recovery. One week prior to presentation he experienced a fall landing on his left shoulder. four days later he presented with severe pain in the left shoulder, a fever of 101 and chills and rigors. In the emergency room, his shoulder was aspirated under radiology guidance for 6 cc of purulent fluid: 80,000 nucleated cells, and 2+ gram positive cocci on stain. His blood work revealed 15 thousand white cells, 78% neutrophils, C reactive protein 24.7, ESR (erythrocyte sedimentation rate) 6. Cultures of the joint fluid grew out MSSA.
The second is the Stealth infection: unexplained pain and stiffness without signs of an obvious infection (i.e fever, chills, elevated blood labs (white cell count, C reactive protein, ESR)) as in this 60 year old man who had a total shoulder for osteoarthritis.
Thirteen years after his arthroplasty he experienced the onset of pain and stiffness of the shoulder. His x-ray at that time is on the right below showing humeral and glenoid component loosening. His blood labs (white blood cell count, C reactive protein and ESR) were normal.
At the time of his revision surgery, his shoulder had cloudy fluid with no white cells, mild synovitis, humeral and glenoid component loosening, a thick humeral membrane and some osteolysis. His intraoperative cultures grew 1+ Cutibacterium from four intraoperative specimens: glenoid explant, glenoid membrane, humeral explant and humeral membrane. Notably his joint fluid showed no growth, so a preoperative joint fluid aspirate would not have been useful.
Comment: Both of these cases met the definition of a periprosthetic infection. The clinical signs and lab tests of the first provided obvious evidence of infection, while those of the second did not.
The only preoperative finding suggesting infection in the second case was humeral component loosening in a male patient as pointed out in Prognostic Factors for Bacterial Cultures Positive for Propionibacterium acnes and Other Organisms in a Large Series of Revision Shoulder Arthroplasties Performed for Stiffness, Pain, or Loosening (red arrows). Blood lab tests (black box) were not helpful in the diagnosing Cutibacterium PJI.
Comments welcome at shoulderarthritis@uw.edu
You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link
Follow on twitter/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
