Tuesday, October 14, 2014

Unsuspected infection in a case of a loose glenoid component - it's not always Propionibacterium

A fifty year old gentleman presented to us with pain in his shoulder after a total shoulder arthroplasty performed elsewhere using a metal-backed glenoid. His x-rays are shown below, showing a dislocated glenoid component.
What would you do?

We performed a revision arthroplasty, removing the glenoid component, retaining the well-fixed humeral stem, smoothing the residual glenoid bone and inserting an eccentric humeral head component. There was no evidence of infection at surgery. Cultures were obtained before antibiotics were administered as is our routine in all revisions. His postoperative films are shown below. He was discharged on the yellow protocol.

His shoulder comfort and function have been dramatically improved.

At six days after surgery. His culture results were as shown below. Click on each to enlarge.

We have the advantage of very experienced infectious disease consultants to guide our approach. A PICC line was inserted and the patient was started on Ceftriaxone 2 gm IV q 24 h. Rifampin 600 mg PO q 24 h was added 8 days later.

The patient experienced diarrhea, C diff was suspected treated with oral Vancomycin X 14 days. His diarrhea resolved.

After 6 weeks of IV antibiotics, his PICC line was discontinued and he was placed on oral Doxycycline Monohydrate 100 MG Oral Cap. He experienced gastrointestinal distress without diarrhea and was switched to Sulfamethoxazole-Trimethoprim 800-160 MG Oral Tab.

His shoulder motion and comfort continue to improved, but he has some aching in his humeral area without radiographic evidence of loosening. We've elected to monitor this for now. In retrospect, perhaps we should have performed a primary exchange of his humeral component. Time will tell.

This case demonstrates the need for a standardized culture protocol for all failed shoulder arthroplasties, the need for close collaboration with experienced infectious disease consultants, and the complexities of the decision making.


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