Background In recreational skiing, an ACL injury is one of the most common diagnosis.

Objective To compare equipment-related risk factors between ACL injured and uninjured skiers.

Design Case-Control study over the 3 winter seasons 2016/17–2018/19 in one major Austrian ski resort.

Participants 248 ACL injured (52% females) and 1054 uninjured skiers (48% females).

Assessment of Risk Factors ACL injury was diagnosed by MRI in a sports clinic located in the ski area. Ski length [m] and side cut radius [m] were taken from the information given on the ski and ski length was relativized to body height [%]. Combined height of ski and binding plate [mm] at the front (H_F) and back part (H_B) of the ski binding, and height at the toe (H_T) and heel piece (H_H) of the ski boot [mm] were measured with a digital sliding caliper. Quotients between H_F and H_B as well as between H_T and H_H were calculated.

Results ACL injured and uninjured skiers did not differ regarding ski length to height ratio (95.3±4.6 vs. 94.9±3.8%, p=.503) or side cut radius (13.9±2.0 vs. 14.4±2.7m, p=.243). Compared to uninjured skiers, ACL injured skiers had a significantly lower absolute mean H_F (40.7±5.7 vs. 38.3±4.8 mm, p <.001, d=0.44) and H_B (44.9±6.7 vs. 39.2±5.1 mm p<.001, d=0.82) and a higher quotient H_F/H_B (0.91±0.08 vs. 0.98 vs, p<.001, d=0.75). Moreover, a lower absolute mean H_T (16.8±2.3 vs. 13.8±1.6 mm, p <.001, d=1.19) and H_H (26.8±2.6 vs. 24.2±1.9 mm, p <.001, d=0.99) and a lower quotient H_T/H_H (0.63±0.09 vs. 0.57±0.06, p <.001, d= 0.65) of the ski boots were found in ACL injured skiers.

Conclusions ACL injured and uninjured skiers differed significantly regarding ski boot sole abrasion and combined height of ski and binding plate, which should be considered as potential risk factors for ACL injuries among recreational skiers.