Table 1.

Combined SPECT/CT criteria for the assessment of loosening of uncemented hip prostheses

		SPECT	CT
A - Acetabular component	1 - Normal	No increased uptake	No radiolucency, no osteolysis
	2 - Physiological remodeling	Increased uptake of surrounding bone at the superior and/or inferior third of the cup	No radiolucency or osteolysis in areas corresponding to SPECT findings (differentiation of surrounding bone and prosthesis-bone interface)
	3 - Pathological loosening	1 - Increased uptake of the whole prosthesis-bone interface	Possibly radiolucency or osteolysis at the prosthesis-bone interface
		2 - Increased uptake of the intermediate third in combination with the inferior or superior third	Possibly radiolucency at the prosthesis-bone interface
		3 - Increased uptake in the superior or inferior third of the component	In combination with a radiolucent line or osteolysis in the area corresponding to SPECT findings
F - Femoral component	1 - Normal	No increased uptake	No radiolucency, no osteolysis
	2 - Physiological remodeling	1 - Increased uptake at the prosthesis-dependent zones not crucial for fixation	Possibly radiolucency at the prosthesis-bone interface, no radiolucency or osteolysis at crucial fixation zones
		2 - Increased uptake of surrounding bone at the crucial fixation zones	No radiolucency or osteolysis in corresponding areas (differentiation of surrounding bone and prosthesis-bone interface)
	3 - Pathological loosening	1 - Increased uptake of the whole prosthesis-bone interface	Possibly radiolucency or osteolysis at the prosthesis-bone interface
		2 - Multifocal uptake with at least one focus within the crucial fixation zone of the prosthesis	Possibly radiolucency or osteolysis at the prosthesis-bone interface