Background: Preventing sport-related lower-extremity injuries relies on identifying individuals at risk. The Landing Error Scoring System (LESS) is a clinical injury risk screening tool suitable for large-scale screening without expensive equipment. However, psychometric properties, influencing factors, and differences in methodological procedures reported between studies need further exploration to justify its use. Furthermore, it is debatable whether the double-leg jump-landing (DLJL) task used in the LESS is ecologically valid and reflects sport and injury-specific situations. Moreover, generalised hypermobility, the Movement-Specific Reinvestment Scale (MSRS), and dorsiflexion range of motion (ROM) have all been used to assess injury risk factors, although their influence on dynamic movements remains relatively unexplored. Aim: To explore the LESS and other clinically assessable sport-related injury risk factors. Methods: Two systematic reviews were undertaken: one on the psychometric properties of the LESS, and another on factors potentially influencing LESS scores. LESS outcomes between different final LESS score calculation methods, self-selected landing distance and landing distance set to 50% of body height, and Pre and Post information sessions on LESS scoring criteria and prior performance were compared using Generalised Estimating Equations, odds ratios, t-tests, McNemar’s, and Wilcoxon signed ranks tests. To determine which jump-landing task best represented the kinematics of a sport-specific and high injury risk task (i.e., unanticipated cutting), the degree of association based on intraclass correlation coefficients (ICC) of three-dimensional whole-body kinematics and ratings of subjective difficulty between unanticipated cutting and four jump-landings were compared using Friedman tests with post-hoc Wilcoxon signed-rank tests. Spearman rank correlation coefficients were calculated to investigate the relationship between LESS, Beighton hypermobility, and MSRS scores. Furthermore, multiple regression models were used to compare three-dimensional whole-body cutting kinematics between asymptomatic hypermobile and non-hypermobile participants, and between cutting kinematics and participants’ dorsiflexion ROM. Results: The overall LESS score demonstrated good-to-excellent reliability (ICC 0.81 to 0.99) and most LESS items had moderate-to-excellent validity against three-dimensional motion analysis measurements. However, the predictive value of the LESS for non-contact lower-extremity injuries remains uncertain. Therefore, the LESS is suitable to evaluate jump-landing kinematics in a clinical setting, but more work is required to ascertain and support its use as a tool to screen for risk of injury. Sex, previous Anterior Cruciate Ligament (ACL) injury, and neuromuscular training programme significantly influenced LESS scores (p ≤ 0.042). The final LESS score calculation method, landing distance, and knowledge of scoring criteria and prior performance altered LESS outcomes. The kinematics of the DLJL were the least associated with those of cutting (ICC 0.00 to 0.81), and rotated DLJL (ICC 0.34 to 0.81) and rotated single-leg jump-landing (SLJLᵣₒₜ) kinematics (ICC 0.31 to 0.80) were the most strongly associated with cutting. Participants rated the SLJLᵣₒₜ as the most difficult task. Asymptomatic hypermobile participants and participants with greater MSRS scores did not present more high-risk movement patterns that could predispose them to ACL injury during jump-landing or cutting. However, dorsiflexion ROM may influence cutting kinematics and contribute to ACL injury risk. Conclusion: Overall, the evidence supports using the LESS for screening of risky movement patterns linked with non-contact lower-extremity injuries. However, incorporating SLJLᵣₒₜ into the LESS may improve its predictive value for sport-related injuries. The use of clinical measures of dorsiflexion ROM may be useful in cutting sports for screening purposes, but not necessarily MSRS or asymptomatic hypermobility.