[1] Univ Coll London Hosp, Dept Trauma & Orthopaed Surg, London, England
[2] Orthopaed Res Inst Galeazzi, Ctr Reconstruct Surg & Osteoarticular Infect, Milan, Italy
[3] Univ Milan, Dept Biomed Sci Hlth, Milan, Italy
[4] IRCCS, Galeazzi Orthopaed Inst, Clin Epidemiol Unit, Milan, Italy
[5] Univ Milano Bicocca, Sch Med & Surg, Ctr Biostat Clin Epidemiol, Monza, Italy
[6] IRCCS, Clin Chem & Microbiol Lab, Galeazzi Inst, Milan, Italy