Subjects can practice until comfortable with the task. No comment or guidance is provided unless performance does not follow the instructions. Any comment or judgment from the tester could disrupt the athlete’s performance and bias the test results. Three trials should be recorded by two off-the-rack video cameras that are installed; one recording the subject from the front (A), and the other recording from the side (B). Each camera should be placed 3m away from the landing zone (Figure 1). The captured movement can then be evaluated at a later time.
How to Score the Landing Error Scoring System (LESS)
Based on a 19-point continuous scale (see FREE performance sheet), the LESS assesses the positioning of the trunk and lower extremities at various stages throughout the Drop-Vertical Jump (DVJ) movement. Using the performance recording sheet, the 1-15 items are scored dichotomically by adding either 1 or 0 to the final scores. Only items 16 and 17 add values 0, 1 or 2 depending on joint displacement and overall impression, respectively. Therefore, a maximal score of 19 can be reached for exceptionally poor performances, while scores <5 are regarded as “good” assuming low-risk for ACL injury .
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Validity and Reliability
The LESS was correlated against the gold standard, that is 3-dimensional motion analysis , and showed that good to excellent inter-rater and intra-rater reliability can be obtained [18, 20]. LESS scoring of six items has “excellent” (84-100%) agreement with 3D motion analysis .
LESS scores may vary widely in young athletes and military populations upon which the LESS was developed [17, 20]. Clear cut-off values for LESS scores dividing low-risk groups from groups with higher risk of obtaining ACL injury are thus difficult to establish. Commonly used cut-off values range between 5-5.5 . This results in ‘labelling’ athletes as low-risk with LESS scores of between 0 and 5, while a high-risk group contains individuals with a LESS score of 5 or higher. More studies must be conducted in the active population before normative data can be established .
It is being questioned whether the DVJ (which is not often associated with ACL injury itself ) is optimally challenging the knee while at the same time offering a safe, controlled and reproducible screening environment. More work should be done to provide enough evidence that increased knee motion during the drop vertical jump landing task actually increases the risk for non-contact ACL injury . Generic bilateral landing tasks (such as the DVJ) have limited predictive ability. To detect high-risk landing postures, sport-specific movements that are associated with ACL injuries may be a more appropriate approach in determining the efficacy .
Repetitive screening is a big part of the job of a sports exercise and medicine clinician. Periodic health evaluations can show underlying pathologies and/or injuries, assess rehabilitation status and establish return-to-sport benchmarks for athletes . The utilisation of high-quality research tools to build an evidence base in sports exercise should focus on specific sports and relevant sub-groups (such as gender) , as well as on the topic of return-to-sport.