Table 2.

Association between patellar alignment (fore groups) and adjusted means of lateral PF joint space narrowing

Measure		Lateral joint space narrowing				p for trend
	Quartile...	1	2	3	4
PLR	No. of knees	50	50	50	52
	Range of PLR	0.66–0.87	0.88–0.98	0.98–1.12	1.13–1.71
	OR (95% CI)	1.00	1.56 (0.66–3.67)	1.36 (0.57–3.23)	2.77 (1.20–6.39)	Linear, 0.0136; U-shaped, 0.1630
SA	No. of knees	51	52	49	50
	Range of SA	98–113	114–119	120–124	125–155
	OR (95% CI)	1.00	1.48 (0.66–3.33)	1.58 (0.71–3.56)	1.43 (0.63–3.24)	Linear, 0.1206; U-shaped, 0.6204
LPTA	No. of knees	52	51	44	54
	Range of LPTA	-25 to 13	14–17	18–21	22–35
	OR (95% CI)	1.00	0.46 (0.21–0.97)	0.32 (0.14–0.73)	0.10 (0.04–0.27)	Linear, <0.0001; U-shaped, 0.9073
BO	No. of knees	49	49	51	50
	Range of BO	38.46–54.55	54.76–60.42	60.47–66.67	66.67–100
	OR (95% CI)	1.00	2.16 (0.78–5.96)	4.22 (1.58–11.25)	8.26 (3.06–22.30)	Linear, <0.0001; U-shaped, 0.2468

Results are adjusted for age, sex and bone mass index. PLR, patellar length ratio; SA, sulcus angle; LPTA, lateral patellar tilt angle; BO, bisect offset; OR, odds ratio; CI, confidence interval.