Table III.

The results of multiple regression analysis with external rotation as the outcome variable. Number of observations = 360.

Variable	Coefficient	SE	t	p > t	95% CI
Neck design (compared to cylindrical neck)
Trapezoidal	2.165	0.176	12.24	< 0.001	1.818 to 2.514
Stem neck-shaft angle (compared to stem with 127° neck angle)
132°	5.775	0.216	26.65	< 0.001	5.349 to 6.202
135°	9.644	0.216	44.5	< 0.001	9.218 to 10.071
Head diameter (compared to 28 mm head)
32 mm	2.481	0.25	9.92	< 0.001	1.989 to 2.974
36 mm	4.704	0.25	18.8	< 0.001	4.212 to 5.196
40 mm	6.525	0.25	26.08	< 0.001	6.033 to 7.018
Hip flexion (compared to -10° of hip extension)
0°	13.77	0.279	49.22	< 0.001	13.22 to 14.321
10°	28.559	0.279	102.09	< 0.001	28.009 to 29.109
45°	67.505	0.279	241.3	< 0.001	66.956 to 68.055
90°	66.832	0.279	238.89	< 0.001	66.281 to 67.382
Femoral stem anteversion (compared to 0° of anteversion)
10° anteversion	-9.983	0.217	-46.07	< 0.001	-10.41 to -9.558
20° anteversion	-19.975	0.217	-92.18	< 0.001	-20.401 to -19.548

CI, confidence interval; SE, standard error.