Table 2.

Mean differences between angular measurement results of parallel (0°) and varying off-z-axis (15° and 45° deviated) double oblique positioning of the femurs on the CT table in the gantry during scanning to test for the independency of femoral positioning.

Femurs: n = 13 Positioning: Three times CT-scans: 39	Subtraction of the results of different positioning angles	Mean	p -value
Femoral torsion angle-neck center	FTA-NC (0°) - FTA-NC (15°)	−0.626	0.075
(FTA-NC)	FTA-NC (0°) - FTA-NC (45°)	−0.933	0.201
	FTA-NC (15°)–FTA-NC (45°)	−0.308	0.362
Femoral torsion angle-neck base	FTA-NBC (0°)–FTA-NBC (15°)	−0.400	0.145
center (FTA-NBC)	FTA-NBC (0°)–FTA-NBC (45°)	−0.523	0.096
	FTA-NBC (15°)–FTA-NBC (45°)	−0.123	0.712
Femoral neck inclination angle-neck	FIA-NC (0°)–FIA-NC (15°)	−0.662	0.124
center (FIA-NC)	FIA-NC (0°)–FIA-NC (45°)	−0.813	0.170
	FIA-NC (15°)–FIA-NC (45°)	−0.151	0.644
Femoral neck inclination angle-neck	FIA-NBC (0°)–FIA-NBC (15°)	0.659	0.131
base center (FIA-NBC)	FIA-NBC (0°)–FIA-NBC (45°)	1.29	0.002
	FIA-NBC (15°)–FIA-NBC (45°)	0.628	0.163
Femoral varus or valgus angle	FVA-td (0°)–FVA-td (15°)	0.359	0.089
total-distal (FVA-td)	FVA-td (0°)–FVA-td (45°)	0.364	0.055
	FVA-td (15°)–FVA-td (45°)	0.005	0.966
Femoral varus or valgus angle	FVA-pd (0°)–FVA-pd (15°)	0.449	0.015
proximal-distal (FVA-pd)	FVA-pd (0°)–FVA-pd (45°)	0.31	0.154
	FVA-pd (15°)-FVA-pd (45°)	0.139	0.283