TABLE III.

The Mean Change in External Rotation with Various Head Size^*

THA Compared with Intact			THA Compared with THA
Head Size	Difference† (deg)	P Value‡	Comparison	Difference† (deg)	P Value‡
28 mm	11 ± 7	0.004§	28 > 32 mm	3 ± 3	0.013§
32 mm	7 ± 6	0.015§	28 > 36 mm	4 ± 5	0.196
36 mm	7 ± 8	0.070	32 = 36 mm	0 ± 4	1.000

^*Data are given as the average across all hip positions (main effect). No interaction was detected (p = 0.067); rather, there was a small effect of head size across all hip positions (p < 0.001). For THA compared with intact, positive values indicate the hip was hypermobile after THA. For THA-THA comparisons, the greater-than symbol (>) indicates which head size had the greater range of external rotation.

^†The values are given as the mean and the 95% confidence interval.

^‡T test.

^§The difference was significant (p < 0.05).