An approach to generate noncontact ACL-injury prone situations on a computer using kinematic data of non-injury situations and Monte Carlo simulation

Figures & data

Figure 1 Musculoskeletal skier with two legs and flexible skis. Blue lines depict trunk and right leg, green lines left leg. Muscles are depicted for right extremity (in red colour).

Figure 2 Distribution of peak ACL forces for right leg (blue bars) and left leg (yellow bars) in n = 1000 simulations.

Figure 3 Box plots of the trunk orientation and joint angles of the leg corresponding to the peak ACL force (hip${}_{\mathrm{p}}$, knee${}_{\mathrm{p}}$, ankle${}_{\mathrm{p}}$) as well as the joint angles of the contralateral leg (subscript CL) in the injury prone cases (a) and the non-injury prone cases (b). The posture of the skier mimicking the corresponding median values is displayed in (c) and (d). For better visualization the snow surface is assumed to be horizontal and the posture of the skier is rotated backward by the slope inclination of 27.8°.

Table 1 Median as well as first and third quartile $[Q_1,Q_3]$ of the trunk and joint angles of the skier at initial ground contact (IGC) corresponding to the injury prone and non-injury prone situations (deg).

Variable	Injury prone	Non-injury prone	P-value
Trunk	−38.4 [−40.8, −35.5]	−50.6 [−57.3, −45.4]	<0.001
Hip	31.3 [27.9, 36.2]	43.8 [37.2, 50.1]	<0.001
Knee	9.7 [6.5, 13.7]	27.6 [19.4, 38.5]	<0.001
Ankle	8.9 [7.2, 11.6]	14.0 [12.9, 15.8]	<0.001
Hip diff	13.2 [7.0, 21.9]	0.2 [−7.9, 7.8]	<0.001
Knee diff	9.6 [3.8, 14.7]	7.1 [−2.0, 14.8]	0.003
Ankle diff	0.4 [−1.1, 1.7]	0.5 [−1.6, 2.5]	0.551

The variables Hip diff, Knee diff and Ankle diff were used to account for asymmetries in the posture of the skier.

Table 2 Spearman rank correlations between the kinematics of the skier at initial ground contact (IGC) and peak ACL force.

Variable	r	P-value
Trunk	0.88	<0.001
Hip	−0.66	<0.001
Knee	−0.78	<0.001
Ankle	−0.68	<0.001
Hip diff	0.42	<0.001
Knee diff	0.20	<0.001
Ankle diff	0.05	0.148

The variables Hip diff, Knee diff and Ankle diff were used to account for asymmetries in the posture of the skier.