Table 1.

Summary of the main articles with the type of specimens used for the histological study and the histological criteria for interpretation of histology as diagnostic of infection.

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 (400x)∗
Lonner 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 (400x)∗
Pons 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 (400x)∗∗
Tohtz 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)∗∗∗

^∗≥1 polymorphonuclear leukocyte per HPF on average after examination of at least 10 HPF; ^∗∗≥23 polymorphonuclear leukocytes in ≥10 HPF (400x). In each HPF, a maximum of 10 polymorphonuclear leukocytes were counted. The sum must be between zero and 100; ^∗∗∗≥2 polymorphonuclear leukocytes per HPF on average after examination of at least 10 HPF.