To investigate the relationship between discharge C-reactive protein (CRP) level of osteoarthritis (OA) patients and periprosthetic joint infection (PJI) after primary unilateral total hip arthroplasty (THA) or total knee arthroplasty (TKA).

From January 2013 to December 2015, 480 OA patients receiving primary unilateral THA or TKA were admitted in department of Orthopedics of Zhongda Hospital Southeast University. The inclusion criteria were normal CRP level before operation, and exclusion criteria were preoperative history of infection, diabetes mellitus, malignant tumors, ect. The patients were divided into the high CRP group (273 cases) and the normal CRP group (207 cases) based on serum CRP level at discharging. Both groups were matched for known confounding factors such as sex, age and discharge time. The hemogram, temperature and wounds of all the patients were normal at discharge, and no antibiotic or NSAIDs were used after discharge. Cases and occurrence time of PJI were recorded during the follow-up. The measurement date were tested by t test, and the incidence of PJI was compared by chi-square test or Fisher’s exact probability method.

Both groups were matched for known confounding factors such as sex, age and discharge time. A total of 415 cases were followed-up after discharge, ranging from 13 to 26 months (18±3) months on average. Although there were three and two PJI cases in both groups respectively at the last follow-up, the results indicated no significant difference in incidence rate of PJI (χ²=0.023, P>0.05). The occurrence time of PJI in the high CRP group was shorter than that in the normal CRP group obviously, and the higher CRP level at discharge, the shorter occurrence time of PJI.

There may be no relationship between discharge CRP level of OA patients and incidence rate of PJI after primary unilateral THA or TKA, however, the patients with high discharge C-reactive protein level should be closely followed up.