Table 1.

Criteria used for diagnosing the reason for revision.

Diagnosis	Diagnostic criteria
Unexplained (+/− pain)	Absence of:
	• Intraoperative loosening of components
	• Infection (see below)
	• Gross malalignment (see below)
	• Component size mismatch
	• Fracture (on imaging/seen intraoperatively)
Acetabular loosening	Intraoperative diagnosis (preoperative imaging has a high false negative rate)
Femoral loosening	Intraoperative diagnosis (preoperative imaging has a high false negative rate)
Infection	Positive if:
	• Postoperative cultures positive for infection
	Negative if:
	• Preoperative CRP less than 10 mg/L or
	• Preoperative CRP greater than 10 mg/L, but postoperative culture was negative for infection
Dislocation	Patient reported (+/- radiographic evidence)
Periprosthetic fracture	Radiographic evidence
Malalignment	Imaging (CT or x-ray) shows:
	• Cup inclination greater than 70°
	• Cup version associated with impingement
Component mismatch	Postoperative assessment of components