Table 1:

McPherson Host Staging System for Periprosthetic Joint Infection

Category	Grade	Description
Infection type	I	Acute early postoperative infection
	II	Acute hematogenous infection
	III	Late chronic infection
Systemic host grade	A	Uncompromised
	B	Compromised (1–2 compromising factors) Severely compromised (>2 compromising factors) or one of the following: Absolute neutrophil count < 1000
	C	CD4 T cell count < 100 Intravenous drug abuse Chronic active infection, other site Dysplasia or neoplasm of the immune system
Local extremity grade	1	Uncompromised
	2	Compromised (1–2 compromising factors)
	3	Significant compromise (>2 compromising factors)

Table adapted from McPherson et al. [11]