Context: Lower extremity bone stress injuries (BSI) place a significant burden on the health and readiness of the US Armed Forces. Objective: To determine if pre-injury baseline performance on an expanded and automated 22-item version of the Landing Error Scoring System (LESS-22) is associated with the incidence of BSI in a military training population. Design: Prospective cohort study. Setting: US Military Academy at West Point Participants: 2,235 (510 females, 22.8%) incoming cadets Main outcome measures: Multivariable Poisson regression models were used to produce adjusted incidence rate ratios (IRR) to quantify the association between pre-injury LESS scores and BSI incidence rate during follow-up, adjusted for pertinent risk factors. Risk factors were included as covariates in the final model if the 95% confidence interval (95% CI) for the crude IRR did not contain 1.00. Results: A total of 54 BSI occurred during the study period, resulting in an overall incidence rate of 0.07 BSI per 1,000 person-days (95% CI: 0.05, 0.09). The mean number of exposure days was 345.4 (SD 61.12, range 3–368). The final model was adjusted for sex and BMI and yielded an adjusted IRR for LESS-22 score of 1.06 (95% CI: 1.002, 1.13; p=0.04), indicating that each additional LESS error documented at baseline was associated with a 6.0% increase in the incidence rate of BSI during the follow-up period. In addition, six individual LESS-22 items, including two newly added items, were significantly associated with BSI incidence. Conclusions: This study provides evidence that performance on the expanded and automated version of the LESS is associated with BSI incidence in a military training population. These results suggest that the automated LESS-22 may be a scalable solution for screening military training populations for BSI risk.

Background: Sport specialization in youth athletes is associated with increased risk for musculoskeletal injury; however, little is known about whether sport specialization is associated with lower extremity movement quality. The purpose of this study was to examine differences in lower extremity movement quality by level of sport specialization in US Service Academy cadets. Hypothesis: Cadets who report an increased level of sport specialization would have a lower level of movement quality than those who are less specialized. Study Design: Cross-sectional analysis from an ongoing prospective cohort study. Level of Evidence: Level 3. Methods: Cadets completed the Landing Error Scoring System (LESS) and a baseline questionnaire evaluating level of sport specialization during high school. Data were analyzed using separate 1-way analysis of variance models. Results: Among all participants (n = 1950), 1045 (53.6%) reported low sport specialization, 600 (30.8%) reported moderate sport specialization, and 305 (15.6%) reported high sport specialization at the time of data collection during the first week. Ages ranged from 17 to 23 years. Men (1491) and women (459) reported comparable specialization levels ( P = 0.45). There were no statistically significant differences in lower extremity movement quality by level of specialization for all subjects combined ( P = 0.15) or when only men were included in the analyses ( P = 0.69). However, there were statistically significant differences in movement quality by level of specialization in women ( P = 0.02). Moderately specialized women had the best movement quality (mean, 4.63; SD, 2.21) followed by those with high specialization (mean, 4.90; SD, 2.08) and those with low levels of specialization (mean, 5.23; SD, 2.07). Conclusion: Women reporting moderate sport specialization had improved movement quality and significantly better LESS scores compared to those with high/low specialization. Clinical Relevance: Athletes, especially women, should be encouraged to avoid early sport specialization to optimize movement quality, which may affect injury risk.