Table 3.

Factors affecting annual percentage change in tibial plateau bone area

Tibial plateau area factorsa	Univariate analysis Regression coefficient (95% CI)	P	Multivariate analysisb Regression coefficient (95% CI)	P
Medial tibial plateau area
Age	-0.10 (-0.23, 0.03)	0.13	-0.07 (-0.18, 0.05)	0.26
Gender	0.94 (-1.78, 3.66)	0.49	-5.42 (-8.67, -2.18)	0.001
BMI	0.43 (0.17, 0.70)	0.002	0.42 (0.16, 0.67)	0.002
Physical activity	-0.85 (-1.58, -0.11)	0.02	-0.30 (-1.00, 0.40)	0.40
Grade of medial osteophytes	0.02 (-1.78, 1.83)	0.98	0.27 (-1.53, 2.07)	0.77
Grade of medial JSN	0.35 (-1.10, 1.80)	0.63	1.88 (0.43, 3.33)	0.01
Baseline medial tibial area	-0.006 (-0.010, -0.003)	<0.001	-0.012 (-0.017, -0.008)	<0.001
Lateral tibial plateau area
Age	-0.02 (-0.10, 0.07)	0.67	-0.01 (-0.11, 0.08)	0.80
Gender	0.25 (-1.62, 2.12)	0.79	-0.08 (-2.51, 2.36)	0.95
BMI	-0.02 (-0.19, 0.15)	0.82	-0.04 (-0.23, 0.16)	0.72
Physical activity	-0.05 (-0.57, 0.48)	0.85	-0.16 (-0.74, 0.41)	0.57
Grade of lateral osteophytes	-0.63 (-1.68, 0.42)	0.24	-0.18 (-1.70, 1.35)	0.82
Grade of lateral JSN	-0.87 (-2.35, 0.61)	0.25	-0.42 (-2.31, 1.48)	0.66
Baseline lateral tibial area	-0.003 (-0.007, 0.001)	0.11	-0.002 (-0.008, 0.003)	0.38

^aFactors were defined as follows: age = percentage change per 1-year increase in age; gender = men compared with women; BMI = percentage change per unit increase in body mass index; physical activity = percentage change per unit increase in physical activity level; grade of osteophytes = percentage change per increase 1 in grade of osteophytes; grade of JSN=percentage change per increase 1 in grade of joint-space narrowing; baseline tibial area = percentage change per 1 mm² increase in baseline tibial plateau bone area. ^bIncludes age, gender, BMI, physical activity, grade of osteophytes, grade of JSN, and baseline tibial plateau bone area in regression equation. BMI, body mass index; JSN, joint-space narrowing.