Table 1.

Relative pose parameter bias±precision calculated from three synthetic fluoroscopic image sets corresponding to an in vivo experimental stair rise motion or randomly transformed bones in a fixed relative pose. Directions are with respect to the anatomic coordinate systems, where A–P is anterior–posterior, S–I is superior–inferior, M–L is medial–lateral, V–V is varus–valgus, I–E is internal–external, and F–E is flexion–extension.

Synthetic images	Pose parameters	Tibiofemoral	Patellofemoral
Set 1	A– P translation (mm)	1.5±2.1a	1.1±1.7a
Ray-Traced	S–I translation (mm)	0.84±0.52a	−0.42±0.95a
Experimental	M –L translation (mm)	7.7±7.3a	9.5±16a
	V–V rotation (deg)	0.33±1.4	−2.6±2.8a
	I–E rotation (deg)	−1.1±0.95a	1.2±2.6a
	F–E rotation (deg)	−0.051±0.49	−0.096±0.86
Set 2	A– P translation (mm)	1.0±2.1a	1.6±3.5a
Ray-Traced	S–I translation (mm)	1.1±1.9a	0.80±1.9a
Random	M –L translation (mm)	3.0±8.1a	7.2±10a
	V–V rotation (deg)	0.53±1.1a	−0.53±2.7
	I–E rotation (deg)	0.22±0.93	0.61±1.6a
	F–E rotation (deg)	−0.25±0.39a	−0.23±0.44a
Set 3	A– P translation (mm)	0.26±0.86	0.070±0.62
Flat-Shaded	S–I translation (mm)	−0.014±0.85	−0.14±0.55
Random	M –L translation (mm)	0.50±3.93	0.75±4.0
	V–V rotation (deg)	0.065±0.62	−0.28±1.3
	I–E rotation (deg)	0.098±0.50	0.37±1.8
	F–E rotation (deg)	−0.058±0.18a	−0.058±0.20

^aBias is statistically different from zero (p<0.05) based on a Student’s t-test.