A study of pre-operative presence of micro-organisms in affected knee joints of rheumatoid arthritis patients who need total knee arthroplasty.

BACKGROUND

To evaluate, by way of intraoperative tissue culture and pathological study, the pre-operative presence of micro-organisms in knee joints of patients with rheumatoid arthritis (RA) who need total knee arthroplasty (TKA).

METHODS

From November 2012 to January 2014, 47 patients with RA (53 knees) who needed TKA were included in this study. Patients received routine pre-operative examination and joint fluid routine and culture. Each RA patient was match-paired with one osteoarthritis (OA) patient. During arthrotomy, synovial tissue was reserved and portioned for culture, frozen section, and routine pathologic examination.

RESULTS

Pre-operative infection in all knees was ruled out. There were 12 RA patients (13 knees) with positive culture results: two Escherichia coli, two Staphylococcus epidermidis, two Staphylococcus aureus, one Proteus mirabilis, one Staphylococcus warneri, one Enterococcus faecalis, one Acinetobacter baumannii, one Candida albicans, one Ochrobactrum anthropi, and one Candida glabrata. Except for microabscess found in one RA patient, all pathological sections showed mild chronic inflammation but no infection. All patients with positive culture results were administered sensitive antibiotics for six weeks after surgery. Two patients had deep infection: one had a fused knee after a failed debridement, and the second was previously treated with an amphotericin injection.

CONCLUSION

Pre-operative presence of micro-organism in knee joints of RA patients is common (24.5%). This finding of a high incidence of pre-operative presence of micro-organism in joints of RA patients before arthroplasty may suggest a role of micro-organism in the pathogenesis of prosthetic joint infection (PJI). Intraoperative synovial tissue culture is valuable for diagnosis of this condition and in instruction of antibacterial treatment.