Reference Specimen Criteria Mirra et al. (1976) [8 ] Synovial and capsular tissues 5 polymorphonuclear leukocytes per HPF in 5 HPF (500x) Fehring and McAlister (1994) [9 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection Evidence of acute inflammation (no quantification) Feldman et al. (1995) [10 ] Joint pseudocapsule and interface membrane 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Athanasou et al. (1995) [11 ] Joint pseudocapsule and interface membrane 1 polymorphonuclear leukocyte per HPF on average in at least 10 HPF (400xLonner et al. (1996) [12 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 and 10 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Pace et al. (1997) [13 ] Joint pseudocapsule and interface membrane 5 polymorphonuclear leukocytes per HPF on multiple (three) HPF (600x)Abdul-Karim et al. (1998) [14 ] Interface membrane (aseptic suspicion). Interface membrane, synovial tissue, and unusually discolored tissue (septic suspicion) 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Spangehl et al. (1999) [3 ] Synovial surface 5 polymorphonuclear leukocytes in any single HPF (400x)Pandey et al. (1999) [15 ] Joint pseudocapsule and interface membrane 1 polymorphonuclear leukocyte per HPF on average in at least 10 HPF (400xPons et al. (1999) [2 ] Synovial surface 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Della Valle et al. (1999) [16 ] Joint pseudocapsule, granulation tissue, and any area that appeared suspicious for possible infection - Banit et al. (2002) [17 ] Joint pseudocapsule and any area that appeared suspicious for possible infection 10 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Musso et al. (2003) [18 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x) Malhorta and Morgan (2004) [19 ] Joint pseudocapsule 5 polymorphonuclear leukocytes per HPF in most areas (400x)Ko et al. (2005) [20 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 polymorphonuclear leukocytes in any single HPF (400x)Wong et al. (2005) [21 ] Synovial surface, joint pseudocapsule, and interface membrane 5 and 10 polymorphonuclear leukocytes per HPF in 5 HPF (400x) Francés Borrego et al. (2006) [22 ] Periprosthetic soft tissue 10 polymorphonuclear leukocytes in any single HPF (400x)Bori et al. (2006) [23 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Morawietz et al. (2006) [24 ] Interface membrane Evidence of acute inflammation (no quantification). Low or high grade. Nuñez et al. (2007) [25 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x) Nilsdotter-Augustinsson et al. (2007) [26 ] Synovial surface and interface membrane 5 polymorphonuclear leukocytes in any single HPF (400x)Della Valle et al. (2007) [27 ] Synovial surface 10 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Bori et al. (2007) [28 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Kanner et al. (2008) [29 ] Periprosthetic soft tissue 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x) Müller et al. (2008) [30 ] Interface membrane Evidence of acute inflammation (no quantification) Schinsky et al. (2008) [31 ] Synovial surface 10 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Fink et al. (2008) [32 ] Periprosthetic tissue 5 polymorphonuclear leukocytes in any single HPF (400x)Schäfer et al. (2008) [33 ] Periprosthetic soft tissue and membrane 5 polymorphonuclear leukocytes per HPF in 10 HPF (400x)Savarino et al. (2009) [34 ] - 1 polymorphonuclear leukocytes in any single HPF (600x)Bori et al. (2009) [35 ] Joint pseudocapsule, interface membrane, and any area that appeared suspicious for possible infection 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Morawietz et al. (2009) [36 ] Interface membrane 23 polymorphonuclear leukocytes in 10 HPF (400xTohtz et al. (2010) [37 ] Interface membrane 2 polymorphonuclear leukocytes per HPF in at least 10 HPF (400x)Stroh et al. (2012) [38 ] Joint pseudocapsule, synovium, and soft tissue Mean of greater than 5 polymorphonucleocytes (PMNs) per HPF was the criteria Miyamae et al. (2013) [39 ] Periprosthetic tissue 10 polymorphonuclear leukocytes in any single HPF (400x)Ahmadi et al. (2013) [40 ] Periprosthetic tissue 5 polymorphonuclear leukocytes in any single HPF (400x)Muñoz-Mahamud et al. (2013) [41 ] Interface membrane 5 polymorphonuclear leukocytes per HPF in 5 HPF (400x)Grosso et al. (2014) [42 ] Joint pseudocapsule and interface membrane ≥10 polymorphonuclear leukocytes per HPF in ≥5 HPF (400x) Buttaro et al. (2015) [43 ] Joint pseudocapsule, interface membrane, and any other tissue involved according to the surgeon’s judgment 5 polymorphonuclear leukocytes per HPF in at least 10 HPF (400x)Kashima et al. (2015) [44 ] Joint pseudocapsule and interface membrane 2 polymorphonuclear leukocytes per HPF on average in at least 10 HPF (400x