Rise in serum C reactive protein after hip and knee arthroplasties in patients with rheumatoid arthritis

Abstract

Objective: Serum C reactive protein (CRP) concentration was evaluated in patients with rheumatoid arthritis (RA) undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) to ascertain the postoperative CRP response.

Methods: Thirty seven consecutive patients with RA who had undergone THA or TKA were included in the study. The CRP concentration was measured in every patient once preoperatively and every other day for one week postoperatively.

Results: The peak median CRP concentration (94 mg/l) was achieved on the first and second day postoperatively and was seven times higher than the median preoperative concentration (13 mg/l). CRP declined to the preoperative concentration in about one week. The rise of the CRP concentration was significant (p< 0.001). No infection was encountered in this series.

Conclusion: A rapid rise in the postoperative CRP concentration is normal in patients with RA treated by THA or TKA. The CRP concentration decreases to the preoperative value in about one week. Serial CRP measurements, including at least one preoperative measurement, are needed when the clinical significance of the postoperative CRP values is evaluated. When the postoperative CRP concentration remains raised for several days compared with the preoperative value, or even rises, it may indicate the presence of a complication in these patients.

Figure 1

Box and whisker plot showing rapid rise and decrease in CRP concentrations. The box part covers the interquartile range and the median; the whiskers extend to include all but outliers, these being indicated separately.