The Development of the Single-Leg Landing Error Scoring System (SL-LESS) for Lower Extremity Movement Screening

Abstract

Introduction: Musculoskeletal knee injuries are some of the most common sports-related injuries. Movement screening assessments are often implemented to identify high-risk individuals in order to prevent the injury and the negative long-term consequences related to sustaining these injuries. While there are numerous established field-based assessments none have shown a strong ability to predict future injury. Additionally, there is currently there is no two-dimensional (2D) screening measure to evaluate the movement of multiple body segments in more than one plane during a single-leg task. The purpose of this study was to investigate the validity and reliability of the Single-Leg Landing Error Scoring System (SL-LESS). Specifically, two aims were addressed: 1) to determine the concurrent validity of the SL-LESS in predicting external knee abduction moment (KAbM) at initial contact and at its peak and 2) to determine the interrater and test-retest reliability of the SL-LESS. Methods: Twenty-eight physically active females were evaluated for risky movement patterns using the SL-LESS during a single-leg drop vertical jump (SLDVJ). This study included two testing sessions that implemented a standardized warm-up and SLDVJ testing protocol. Two-dimensional videos of the frontal and sagittal planes were collected during session 1 while both 2D videos and three-dimensional (3D) kinematics and kinetics were collected during session 2. SL-LESS scores from session 2 were used to stratify participants into 3 groups (good, moderate, poor). Differences KAbM at initial contact and at its peak between the “good” and “poor” groups were investigated using an independent-samples t tests. Intraclass correlation coefficients (ICC2,1) were used to determine the interrater reliability of session 1 total SL-LESS scores between two raters and test-retest reliability of total SL-LESS scores between sessions. To determine the agreement of the individual SL-LESS items, percent agreement and Cohen’s kappa statistic were calculated to for each of the 11 items. Results: No statistical differences were found in KAbM at initial contact between groups or maximum KAbM between groups. The SL-LESS demonstrated fair interrater reliability and good test-retest reliability. Individual item percent agreement between raters ranged from 75.0–100% and kappa statistics indicated significant fair to perfect agreement. Between sessions percent agreement ranged from 78.6–100% and kappa statistics indicated significant moderate to perfect agreement. Conclusions: The results of this study indicate that this initial version of the SL-LESS does not predict KAbM. It does, however, provide the basis for a new single-leg, whole body movement analysis that future studies can build upon in order to develop a valid lower extremity injury screening assessment that can be easily implemented in a variety of field and clinical settings.