This is a meta-analysis of six studies describing the cutoff values of white blood cell count and polymorphonuclear percentage in synovial fluid for the diagnosis of acute postoperative peri-prosthetic joint infection (PJI). 
We found that both the WBC count and PMN percentage are good markers for diagnosis of acute postoperative PJI. However, the synovial WBC count is more powerful in diagnosing acute postoperative PJI.

Management of septic arthritis in native joints (SANJO) is often conducted by clinicians of different specialties, experience levels, and at all hours of the day. The SANJO guideline group makes evidence-based recommendations for diagnosis, microbiological investigation, initial surgery, empirical antibiotic treatment, early mobilization, evaluation of outcomes, and treatment failure. Special considerations were made for children, tuberculosis, and SANJO after cruciate ligament reconstruction.

Our multicentre study on a lower-limb osteosynthesis-associated infection (OAI) cohort by multidrug (MDR) and extensively drug (XDR) resistant Gram-negative bacteria found the following: implant retention with debridement was mostly performed in early OAI; 50.9 % of patients achieved remission of infection; remission reached 50 % (MDR) vs. 25 % (XDR) in early OAI and 60 % (MDR) vs. 44.4 % (XDR) in late OAI; age (> 60) and multiple surgeries were independent factors influencing lack of remission.

A patient with normal D-dimer value has a low risk of prosthetic joint infection, so serum D-dimer assessment should always be considered as a useful test to rule out chronic prosthetic joint infection (especially in those cases caused by low-virulence microorganisms in which conventional tests may lead to misdiagnosis). Conversely, the platelet count to mean platelet volume ratio may be of limited value for accurately diagnosing prosthetic joint infection.

Our data suggest that, in periprosthetic joint infection (PJI) patients with a draining sinus, suppressive antibiotic treatment (SAT) can be considered on an individual basis. SAT may reduce pain and favour the closure of the sinus tract in certain individuals, but the prescription of SAT does not appear to have any influence on the prevention of prosthetic loosening and other infectious complications.