Femoral periosteal reaction in the mid-piece of the prosthesis: a potential predictor of hip prosthetic joint infection

[Background] Early diagnosis of HPJI is important. Periosteal reaction has been shown to diagnose osteomyelitis and bone tumours; however, research on artificial joint infections is not clear. The purpose of this study was to analyse the diagnostic possibility of FPR on X-ray films for HPJI. [Methods] From January 2017 to June 2019, 105 patients who underwent artificial hip joint revision surgery were retrospectively included in the single joint surgery centre. Based on the description by the MSIS in 2013 and exclusion of patients with bone tumour revisions, 66 patients were reviewed and divided into the PJI group and aseptic failure (AF) group. The clinical outcome and radiographic results were examined by two experienced joint surgeons independently on hip X-ray images in all cases. Sensitivity, specificity, PPV and NPV were calculated for FPR in HPJI, and the imaging results were compared with those of serology and bacterial culture. [Results] A total of 16 patients in the PJI group were positive for FPR with appearance in the mid-piece and distal part, while 6 patients in the AF group (43.3% vs 26.1%, p = 0.04) were positive for FPR. Only 1 patient in the AF group had a mid-piece FPR, and the rest were at the distal end. Separated measurements were unidimensional (Kappa value = 0.89). The process of FPR-positive patients in the PJI group was 13 ± 26.1 months, and it was 9.83 ± 8.2 months in the AF group, and the difference was not statistically significant (p = 0.67). There was no connection between the responsible pathogens and FPR in the PJI group. The sensitivity, specificity, PPV and NPV for FPR at any section were 43.2%, 79.3%, 72.7% and 52.7%, respectively. The mid-piece FPR improved by 43.2%, 96.5%, 94.1% and 57.1%, respectively. Combined with elevated serum CRP/ ESR, specificity and PPV could reach 100%. [Conclusion] Preoperative X-ray examinations revealed that the mid-piece FPR requires a high degree of suspicion of PJI. If patients have elevated serum CRP/ESR at the same time, joint puncture and other methods should be used to obtain culture results to confirm the diagnosis.