Table 2.

Predictors of maximum cartilage alpha angle

		Number of hips	Univariate regression			Multivariable regression 1*			Multivariable regression 2†			Multivariable regression 3‡
			Coefficient	95% CI	p Value	Coefficient	95% CI	p Value	Coefficient	95% CI	p Value	Coefficient	95% CI	p Value
Months of age		420	0.242 –	0.14 to 0.34	0.020	0.268	0.17 to 0.37	0.019	0.273	0.18 to 0.37	0.018	0.290	0.10 to 0.480	0.033
Age category (years)	9–10	118	–	–	–
	11–12	92	6.08	5.94 to 6.21	0.001
	13–14	80	16.23	7.42 to 25.03	0.027
	15–16	100	17.97	9.37 to 26.56	0.024
	17–18	30	18.48	13.67 to 23.29	0.013
Physis	Open	247	–	–	–
	Closed	168	13.24	6.73 to 19.74	0.025
Gender	Male	310	–	–	–	–	–	–				–	–	–
	Female	110	−6.05	−9.74 to 2.35	0.031	−6.66	−7.26 to −6.06	0.005				−9.64	−14.75 to −4.53	0.027
BMI		420	1.40	1.02 to 1.78	0.013
Dominant leg	Dominant	231	–		–
	Non-dominant	189	0.856	−38.21 to 39.93	0.827
Cohort	Male control	104	–	–	–				–	–	–
	Female control	110	−3.37	−4.22 – −2.52	0.013				−7.42	−8.01 to −6.83	0.004
	Football academy	206	4.05	−0.36 to 8.46	0.054				4.33	0.67 to 7.99	0.042
Activity level	No sport	70	–	–	–	–	–	–
	Sport	140	6.21	3.37 to 9.05	0.023	4.03	0.74 to 7.33	0.041
	Athlete	210	10.50	4.38 to 16.61	0.029	7.63	2.23 to 13.04	0.035
Physical Activity Questionnaire		420	−3.15	−5.58 – −0.71	0.039							1.52	−6.48 to 9.53	0.250
Table 2b Predictors of epiphyseal extension at 1 o’clock
Months of age		420	0.0018	0.0018 to 0.0019	<0.001	0.0019	0.0024 to 0.0317	0.002	0.0019	0.0018 to 0.0020	0.002	0.0019	0.0017 to 0.0021	0.006
Age category (years)	9–10	118	–	–	–
	11–12	92	0.0384	0.0276 to 0.0492	0.014
	13–14	80	0.0929	0.0848 to 0.1011	0.004
	15–16	100	0.1375	0.0804 to 0.1945	0.021
	17–18	30	0.1571	0.0840 to 0.2301	0.023
Physis	Open	247	–	–	–
	Closed	168	0.1169	0.1006 to 0.1331	0.007
Gender	Male	310	–	–	–	–	–	–				–	–	–
	Female	110	0.0085	−0.0064 to 0.0234	0.087	−0.0058	−0.0203 to −0.0087	0.124				−0.0214	−0.0506 to 0.0077	0.068
BMI		420	0.0127	0.0103 to 0.0150	0.009
Dominant leg	Dominant	231	–	–	–
	Non-dominant	189	0.0047	−0.1828 to 0.1923	0.802
Cohort	Male control	104	–	–	–				–	–	–
	Female control	110	0.0221	0.0191 to 0.0252	0.013				−0.0062	−0.0105 to −0.0029	0.034
	Football academy	206	0.0205	0.0030 to 0.0381	0.043				0.0225	0.0003 to 0.0447	0.049
Activity level	No sport	70	–	–	–	–	–	–
	Sport	140	0.2442	0.0068 to 0.0421	0.036	0.0171	0.0024 to 0.0317	0.043
	Athlete	210	0.0274	0.0096 to 0.0452	0.033	0.0322	0.0183 to 0.0020	0.022
Physical Activity Questionnaire		420	−0.0397	−0.0552 to −0.0243	0.019							−0.0010	−0.0253 to 0.0234	0.701

*Age, gender and activity level as covariables.

†Age and cohort as covariables.

‡ Age, gender and Physical Activity Questionnaire as covariables.

BMI, body mass index.