Table IV.

The results of multiple regression analysis with internal rotation as the outcome variable. Number of observations = 144.

Variable	Coefficient	SE	t	p > t	95% CI
Neck design (compared to cylindrical neck)
Trapezoidal	3.328	0.302	11.01	< 0.001	2.73 to 3.926
Stem neck-shaft angle (compared to stem with 127° neck angle)
132°	-1.52	0.37	-4.1	< 0.001	-2.251 to -0.787
135°	-2.646	0.37	-7.14	< 0.001	-3.378 to -1.913
Head diameter (compared to 28 mm head)
32 mm	2.378	0.427	5.56	< 0.001	1.531 to 3.224
36 mm	4.289	0.427	10.03	< 0.001	3.443 to 5.135
40 mm	5.712	0.427	13.36	< 0.001	4.865 to 6.557
Hip flexion (compared to 90° of hip extension)
110°	-18.786	0.302	-62.13	< 0.001	-19.384 to -18.189
Femoral stem anteversion (compared to 0° of anteversion)
10° anteversion	9.978	0.37	26.94	< 0.001	9.245 to 10.71
20° anteversion	19.99	0.37	53.98	< 0.001	19.258 to 20.722

CI, confidence interval; SE, standard error.