Table 4.

Anterior Cruciate Ligament Injuries by Season Segment^a

Variable	Preseason	Early Regular Season	Middle Regular Season	Late Regular Season	Postseason
All injuries
No.	40	72	44	45	8
AEs	384 573	371 705	335 182	363 227	90 771
Rate per 10 000 AEs (95% CI)	1.04 (0.72, 1.36)	1.94 (1.49, 2.38)	1.31 (0.92, 1.70)	1.24 (0.88, 1.60)	0.88 (0.27, 1.49)
Noncontact
No.	22	45	20	21	2
AEs	384 573	371 705	335 182	363 227	90 771
Rate per 10 000 AEs (95% CI)	0.57 (0.33, 0.81)	1.21 (0.86, 1.56)	0.60 (0.34, 0.86)	0.58 (0.33, 0.83)	0.22 (0.00, 0.53)
All injuries IRR (95% CI)
Versus preseason		1.86 (1.27, 2.74)b	1.26 (0.82, 1.94)	1.19 (0.78, 1.82)	0.85 (0.40, 1.81)
Versus early regular season		–	0.68 (0.47, 0.99)b	0.64 (0.44, 0.93)b	0.45 (0.22, 0.94)b
Versus middle regular season		–	–	0.94 (0.62, 1.43)	0.67 (0.32, 1.43)
Versus late regular season		–	–	–	0.71 (0.34, 1.51)
Noncontact IRR (95% CI)
Versus preseason		2.12 (1.27, 3.52)b	1.04 (0.57, 1.91)	1.01 (0.56, 1.84)	0.39 (0.09, 1.64)
Versus early regular season		–	0.49 (0.29, 0.83)b	0.48 (0.28, 0.80)b	0.18 (0.04, 0.75)b
Versus middle regular season		–	–	0.97 (0.53, 1.79)	0.37 (0.09, 1.58)
Versus late regular season		–	–	–	0.38 (0.09, 1.63)

Abbreviations: AE, athlete-exposure; CI, confidence interval; IRR, incidence rate ratio.

^aAnalysis includes a subset of data restricted to 2009–2010 through 2015–2016.

^bP < .05.