The natural trends of C-reactive protein after hip arthroplasty for femoral neck fracture without infection

The aim of this study was to estimate the degree of normalization of C-reactive protein (CRP) at 2-weeks and 4-weeks after hip arthroplasty after femoral neck fracture. We also wished to determine whether the degree of CRP normalization differs after total hip arthroplasty (THA) compared to bipolar hemiarthroplasty (BH). We also wanted to analyze the patient factors that may influence CRP normalization. We conducted a retrospective study of 135 patients who had undergone THA (32 cases) or BH (103 cases) for femoral neck fracture by single surgeon from January 2015 to December 2019. We analyzed CRP levels during the preoperative period, the early postoperative period, the 2-week postoperative period, and the 4-week postoperative period. In THA, CRP was normalized in 4 patients (12.5%) and in 15 patients (46.9%) within 2-weeks and 4-weeks after surgery, respectively. In BH, CRP was normalized in 16 patients (15.5%) and in 52 patients (50.5%) within 2-weeks and 4-weeks after surgery, respectively. There were no statistical differences between THA and BH. Compared to women, men were 3.78 (95% confidence interval, 1.05–13.63) times less likely to have normalized CRP at 2-weeks after surgery (P = .042). Compared to women, men were 3.01 (95% confidence interval, 1.44–6.27) times less likely to have normalized CRP at 4-weeks after surgery (P = .003). Only 50% of patient's CRP level was normalized during 4-week postoperative period. In men, CRP levels were significantly higher than women in whole period. In the case of THA, the CRP level was higher only in early postoperative period compared to BH, and there was no difference since then.