Risk of Anterior Cruciate Ligament Injury in Female Soccer Players With Increased Lateral Plantar Loading and Reduced Medial Metatarsal Loading During Running: A Prospective Study

Background: Anterior cruciate ligament (ACL) injuries are common among female soccer players and often result in long-term absence from sport. Despite extensive studies on ACL injury mechanisms, no prospective studies have investigated the distribution of dynamic plantar loading during running in players who later sustain ACL injuries. Purpose: To prospectively investigate the characteristics of plantar pressure during running in female soccer players who sustained ACL injuries. Study Design: Case-control study; Level of evidence: 3. Methods: A total of 121 female high school and collegiate soccer players with no history of ACL injury were enrolled. Dynamic plantar loading distribution during running was measured at baseline. Participants were monitored for 1 year and classified into an ACL injury group (ACL group) or a control group (CON group) with no injuries. Plantar pressure was analyzed across 6 regions of the foot: medial and lateral regions of the forefoot, midfoot (metatarsal), and hindfoot. Cumulative load, peak force, and the medial-to-lateral force ratio were compared between the groups. Results: The ACL group (11 players, 13 limbs) demonstrated significantly lower cumulative loading at the first and second medial metatarsal regions compared to the CON group (100 players, 200 limbs). The median cumulative load (N/kg) adjusted for body weight at the first metatarsal was 158.46 in the ACL group and 208.97 in the CON group ( P = .01). At the second metatarsal, the values were 127.76 and 153.23, respectively ( P = .04). The medial-to-lateral force ratio (%) was significantly lower in the ACL group (82.5%) than in the CON group (97.3%, P = .03). Conclusion: Female soccer players who sustained ACL injuries exhibited reduced medial metatarsal loading and a lower medial-to-lateral plantar force ratio during running. These findings suggest that altered plantar loading patterns may contribute to ACL injury risk.