Is ski boot sole abrasion a potential ACL injury risk factor for male and female recreational skiers?

OBJECTIVES: To evaluate the potential impact of ski boot sole abrasion on the ACL injury risk of recreational skiers. METHODS: During the past two winter seasons 2016/17 and 2017/18, this retrospective case‐control study was conducted in one Austrian ski area. Among a cohort of 148 ACL‐injured (51.4% females) and 455 uninjured recreational skiers (43.3% females), age, sex, height, weight, and self‐reported skill level were collected by questionnaire, ski length and sidecut radius were notated and sole abrasion of the toe and heel piece of the ski boot was measured using a digital caliper. RESULTS: ACL‐injured skiers showed a higher proportion of female (51.4% vs 43.3%, P < 0.001) and less skilled skiers (48.6% vs 20.9%, P < 0.001), and ski length to height ratio was higher (94.7 ± 3.7 vs 93.8 ± 5.0%, P = 0.019) compared to uninjured skiers. ACL‐injured skiers used ski boots of greater abrasion at the toe (4.8 ± 1.8 vs 2.4 ± 2.5 mm, P < 0.001) and heel piece (5.4 ± 1.8 vs 3.3 ± 2.3 mm, P < 0.001) compared to controls. Multivariate regression analysis revealed, beside female sex (OR 6.0, 95% CI, 3.1‐11.5, P < 0.001), lower skill level (OR 3.2, 95% CI, 1.9‐5.4, P < 0.001) and ski length to height ratio (OR 1.1, 95% CI, 1.0‐1.2, P < 0.001), sole abrasion at the toe (OR 1.8, 95% CI, 1.5‐2.1, P < 0.001) and heel piece (OR 1.4, 95% CI, 1.2‐1.6, P < 0.001) to be independently associated with an ACL injury among recreational alpine skiers. CONCLUSIONS: Based on the underlying findings, ski boot sole abrasion was found to be an independent risk factor and may contribute to an increased ACL injury risk.