In the treatment of knee periprosthetic joint infection with a two-stage protocol, static spacers allow for the local delivery of high doses of antibiotics and help to preserve soft tissue tension. Articulated spacers were introduced to better preserve flexion after the reimplantation. The aim of this systematic review is to provide a comprehensive data collection of the results of these different spacers. An in-depth search on the main clinical databases was performed concerning the studies reporting data on the topic. A total of 87 studies and 4250 spacers were included. No significant differences were found both in pooling data analysis and meta-analysis of comparative studies about infection recurrences, complications, and clinical scores. Mean active knee flexion at last follow-up after total knee reimplantation was found to be significantly higher using articulated spacers (91.6° ± 7° for static spacers vs. 100.3° ± 9.9° for articulated spacers; p < 0.001). Meta-analysis also recognized this strong significant difference (p < 0.001). This review has confirmed that articulated spacers do not appear to be inferior to static spacers regarding all clinical outcomes, while they are superior in terms of active flexion. However, the low quality of the studies and the risk for selection bias with complex patients preferentially treated with static spacers need to be accounted for.

Antibiotic-laden bone substitutes represent a viable option in the treatment of bone and joint infections with bone defects. In particular, the addition of silver ions or silver nanoparticles to bone substitutes to achieve local antiseptic activity could represent a further contribution, also helping to prevent bacterial resistance to antibiotics. An in-depth search of the main scientific databases was performed regarding the use of silver compounds for bone substitution. The available evidence is still limited to the preclinical level: 22 laboratory studies, 2 animal models, and 3 studies, with both in vitro and in vivo analysis, were found on the topic. Numerous biomaterials have been evaluated. In vitro studies confirmed that silver in bone substitutes retains the antibacterial activity already demonstrated in coatings materials. Cytotoxicity was generally found to be low and only related to silver concentrations higher than those sufficient to achieve antibacterial activity. Instead, there are only a few in vivo studies, which appear to confirm antibacterial efficacy, although there is insufficient evidence on the pharmacokinetics and safety profile of the compounds investigated. In conclusion, research on bone substitutes doped with silver is in its early stages, but the preliminary findings seem promising.

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Introduction Temporary spacers used in the staged revision of a hip prosthetic joint infection (PJI) have been associated with several mechanical complications with very variable reported general complications rates up to 73%. The aim of this systematic review was to assess the mechanical complications associated with hip antibiotic-loaded spacers when treating periprosthetic hip PJI. Methods Through an electronic systematic search of PubMed, articles reporting mechanical complications of spacers used in the treatment of hip PJI were reviewed. Dislocations, spacer fracture, femoral fractures, and acetabular lysis rates were evaluated. Results Forty studies were included. Standardized molded spacers had a significantly higher weighted mean of total mechanical complication rates (37.2%) when compared to standardized preformed spacers (13.8%, p = 0.039), while no significant difference was found between molded spacers and manually shaped spacers. Spacer dislocation was the most frequent complication. No significant difference in mechanical complication rate was found between spacers with and without any metallic component. Conclusions Spacer placement in chronic PJI of the hip with bone and soft-tissue defects is challenging and bears a high risk of mechanical failures and progressive bone loss during the interim period. A careful patient selection for spacer implantation is mandatory.

Prosthetic joint infections (PJIs) occurring in multiple joints at the same time (synchronous PJI) are an extremely rare complication, frequently associated with bacteremia, and are associated with high mortality rates. The presence of three or more prosthetic joints, rheumatoid arthritis, neoplasia, bacteremia and immune-modulating therapy seem to be the recurring risk factors for synchronous PJI. In case of PJIs, all other replaced joints should be considered as potentially infected and investigated if PJI is suspected. Treatments of synchronous multiple PJIs vary and must be decided on a case-by-case basis. However, the advantages of one-stage exchange seem to outweigh the two-stage protocol, as it decreases the number of necessary surgical procedures. Nonetheless, too few studies have been conducted to allow firm conclusions about the best handling of synchronous PJI. Thus, additional studies are needed to understand this devastating complication and to design the most appropriate diagnostic and therapeutic path.