Background:After total hip arthroplasty (THA),there is a noteworthy inflammatory response.The inflammatory response is associated with postoperative recovery and complications.However,there had been few reports on the relationship between inflammatory response and postoperative complication rate.The aim of the present study was to investigate early inflammatory response in the first 3 days after THA,and to identify the relationship between inflammatory response and estimated complication rate after surgery.Methods:It was a prospective,nonrandomized cohort study.There were 148 patients who underwent unilateral THA in our hospital enrolled.Blood samples were collected preoperatively in the ming of the surgery and at 24,48,and 72 h after surgery.C-reactive protein (CRP) and interleukin-6 (IL-6) in peripheral blood were measured.The modified physiological and operative severity score for the enumeration of the morbidity (POSSUM) was recorded pre-and intra-operatively.Based on the score,estimated complication rate was calculated.Harris score was used to assess hip function before and after surgery.Results:IL-6 levels reached the peak at 24 h after surgery and CRP at 48 h.After that,both of the levels decreased.The mean Harris scores significantly increased from 41.62 ± 23.47 before surgery to 72.75 ± 9.13 at 3 days after surgery.The Harris scores after surgery did not have a significant relation with either IL-6 or CRP peak levels (P=0.165,P =0.34 l,respectively).Both CRP and IL-6 peak levels significantly and positively correlated with estimated complication rate after surgery.The estimated complication rate calculated using the POSSUM system was 43 cases of 148 patients.Actually,there were only 28 cases that were observed to get postoperative complications during hospitalization.However,there was no significant difference between estimated and observed complication rates (P =0.078).In the group with complications,the CRP and IL-6 peak levels were significantly higher than those in the group without complications (both P ＜ 0.001).Conclusions:There were significantly positive relationships between both peak levels of CRP and IL-6 and estimated complication rate after THA.Inflammatory response could predict the incidence of complications after THA.