ABSTRACT
Objective:To investigate the clinical characteristics and risk factors for patients with chronic periprosthetic joint infection (PJI) combined with sinus tract.Methods:The patients with PJI following hip and knee arthroplasty from July 2014 to January 2020 in our institution were retrospectively reviewed. There were 96 males and 101 females, aged from 26 to 86 years with mean age of 62.02±13.54 years. There were 95 hip PJI patients (48.2%, 95/197), 102 knee PJI patients (51.8%, 102/197), 68 patients (34.5%, 68/197) with sinus tract, 129 patients (65.5%, 129/197) without sinus tract, 162 patients (82.2%, 162/197) with positive culture results and 35 patients (17.8%, 35/197) with negative culture results. The patients were divided into two groups according to the sinus tract formation. The diagnosis of PJI was based on the 2011 Musculoskeletal Infection Society (MSIS) criteria. All of the included patients underwent serological laboratory tests (white blood cell count, neutrophil percentage, lymphocyte percentage, hemoglobin, platelet count, mean platelet volume, urea, creatinine, albumin, erythrocyte sedimentation rate, C-reactive protein) and pathogen isolation. The influence of sinus tract on the above test and the effects of complications on sinus tract formation were analyzed. We further investigated the relationship between sinus tract formation and the features of pathogen. In addition, the risk factors for sinus tract formation were analyzed.Results:The mean values of all serological tests were without statistical difference between the groups with and without sinus tract ( P>0.05). The presence of complications had no effect on the occurrence of sinus tract ( P>0.05). The incidence of sinus tract with highly virulent pathogen infection group (52.1%, 25/48) was significantly higher than that in low virulence pathogen group (27.5%, 19/69), in culture negative patients (40.0%, 14/35) and in other cases (22.2%, 10/45; χ 2=11.519, P=0.009). There was no statistical difference between groups based on the Gram staining, antibiotic resistance and polymicrobial infection. Multivariate logistic regression analysis revealed positive associations of extra joint infections ( OR=4.426, 95% CI: 1.095, 17.884) and high virulent pathogen infections ( OR=2.633, 95% CI: 1.171, 5.918) and negative association of age ≥70 ( OR=0.436, 95% CI: 0.205, 0.927) with the risk of sinus tract formation. Conclusion:The presence of sinus tract has no effect on the routine serum tests in patients with chronic PJI. There is only virulence factor which might affect sinus tract formation. For patients with the extra joint infections and high virulence pathogen infections, the formation of sinus tract should be vigilant during treatment.