Objective:To explore the clinical outcomes of articulating spacers in the treatment of chronic knee periprosthetic joint infection (PJI).Methods:A retrospective study was conducted of the 38 patients who had undergone stage-two revision for chronic knee PJI from January 2014 to January 2020 at Department of Articular Surgery, The First Affiliated Hospital to Fujian Medical University. They were 8 men and 30 women, aged from 37 to 84 years (average, 66.2 years). The PJI was unilateral in all, affecting 19 left sides and 19 right sides. According to the kind of spacers used in the stage-one revision, they were divided into 3 groups: metal-polyethylene one (10 cases), metal-cement one (15 cases) and cement one (13 cases). In the stage-two revision following infection control, the spacers were removed for sonication and microbial culture. Infection control, range of motion (ROM), Knee Society Score (KSS), and complications were followed up.Results:The 38 patients were followed up for an average of 30.8 months (from 13 to 75 months). All patients underwent spacer implantation at stage-one revision and infection was controlled in 37 of them (97.4%, 37/38). After stage-one revision, metal-polyethylene, metal-cement and cement groups achieved 95.0°±11.3°, 92.9°±8.3° and 75.5°±11.9° in ROM, 79.4±6.1, 77.3±4.0 and 73.0±7.2 in clinical KSS and 67.5±11.8, 69.0±10.4 and 60.8±11.0 in functional KSS, showing significant improvements in the above indexes between preoperation and postoperation ( P<0.05). The ROMs for the metal-polyethylene and metal-cement groups were significantly better than for the cement group ( P<0.05). A total of 32 patients completed stage-two revision, with 7 in the metal-polyethylene group, 12 in the metal-cement group and 13 in the cement group. Respectively, ROMs after stage-two revision were 104.6°±9.8°, 98.5°±8.7° and 86.1°±8.9°, clinical KSSs 85.3±4.6, 82.7±4.3 and 78.0±4.8 and functional KSSs 78.6±6.9, 77.3±8.2 and 69.5±8.3 for the metal-polyethylene, metal-cement and cement groups, showing significant improvements after stage-one revision ( P<0.05). The postoperative sonication fluid culture showed negative results in all. Conclusions:Articulating spacers can effectively control knee PJI and improve the knee function during revision interval and after revision. Metal spacers may lead to a better range of motion than traditional cement ones.

Objective:To investigate the value of metagenomic Next-Generation Sequencing (mNGS) in etiological diagnosis of osteoarticular nontuberculous mycobacterial (NTM) infection.Methods:From January 2014 to October 2019, 119 patients were definitely diagnosed as osteoarticular infection at Department of Bone Tumor & Joint Surgery, The First Affiliated Hospital to Fujian Medical University. All of them underwent conventional culture followed by mNGS to screen out those with NTM infection by the etiological testing. Optimized culture was conducted for NTM infections. Demographic data, and results of conventional culture, mNGS and optimized culture were recorded for patients with NTM infection.Results:mNGS showed that 12 of the 119 patients with osteoarticular infection (12/119, 10.1%) had NTM infection. They were 6 males and 6 females aged from 31 to 82 years(average, 51.1 years). There were 5 cases of slowly-growing mycobacterial type and 7 cases of rapidly-growing mycobacterial type. The positive rate of primary culture was only 16.7% (2/12) by the conventional culture, but increased to 66.7% (8/12) by the optimized culture. The positive rate of optimized culture was 100% (7/7) for the rapidly-growing mycobacterial type and 20% (1/5) for the slowly-growing mycobacterial type.Conclusion:As the positive rate of conventional culture is low for patients with osteoarticular NTM infection, mNGS is superior due to its advantage in accurate etiological diagnosis, especially for that of rapidly-growing mycobacterial type.