Periprosthetic Joint Infection With Actinomyces radingae May Lead to the Identification of a Neglected Source of Intraoperative Contamination

Abstract

Periprosthetic joint infection remains a major complication in arthroplasty. We present the first description of a case of periprosthetic joint infection with Actinomyces radingae, microorganism that is mostly found on the skin of the upper body and might cause particular challenges as it is difficult to culture and specify. Furthermore, a thorough microbiologic workup may indicate the source of infection. In this case, it is possible that perspiration from the surgeon was the source of intraoperative contamination. Intraoperative contamination through perspiration may be important and should be avoided by all means.

Keywords: Actinomyces radingae; PJI; Periprosthetic joint infection; THA; Total hip arthroplasty.

Figure 1

Zone of interest of the conventional radiographs of the pelvis showing the right hip of the 51-year-old patient described. (a) Situation prior to THA. Note the postoperative and posttraumatic alterations of the proximal femur, after internal fixation (black arrows). Osteoarthritis was mainly posteroinferior. (b) postoperative control after THA. The cup is seated slightly too medially, the medial border crossing the ilioischial line (black arrowheads), and cranially. Leg length and femoral offset were reconstructed properly. (c) Radiograph after 4 months. Note loosening of the cup and shortening of the leg consecutive to migration of the cup. (d) After revision with debridement, exchange of the cup and implantation of vancomycin-loaded calcium sulphate beads (asterisk). Note restoration of an anatomic centre of rotation, with the cup not protruding anymore medially to the ilioischial line (black arrowheads). (e) Eighteen months after revision, showing no signs of loosening. Particularly, the residual sclerotic bone of the acetabulum resorbed, indicating proper integration of the cup. The calcium sulphate beads dissolved within months.

Figure 2

Scanning electron micrograph of Actinomyces radingae biofilm. Biofilm was grown over 48 hours on medical-grade titanium-aluminum-niobium disc and showed numerous clusters of cells, suggestive of microcolony or biofilm formation. Additionally, note the extracellular polymeric substances appearing to cover partially the cluster on the right-hand side. Biofilms were fixed with ethanol, sputter-coated with gold and palladium, and imaged using a Hitachi S-4700 field emission scanning electron microscope. We counted how many cells were within the biofilm, and it was approximately 100,000 per disc. This is less than we would expect from a staphylococcal biofilm by about 20- to 50-fold.