The Utilization of the Landing Error Scoring System in Patients' Postanterior Cruciate Ligament Reconstruction: An Exploratory Factor Analysis.

Abstract

Context: The landing error scoring system (LESS) was developed to screen healthy individuals for anterior cruciate ligament  (ACL) injury risk factors using a jump landing task. The purpose of this study was to evaluate unique landing error components of a modified LESS scoring criteria to determine its clinical utility in patients following ACL reconstruction (ACLR).

Design: An observational cross-sectional study design was implemented to determine if each individual error component of the modified LESS provided unique information in an ACLR patient population.

Methods: Post-ACLR patients (N = 194 [47.9% female]) completed the LESS 7.91 (1.80) months after surgery. To complete the LESS, patients stood on a 30-cm plyometric box and jumped down to a ground target, at 50% of their height in front of the box, then completed a maximal vertical jump. The LESS was repeated 3 times. Two video cameras positioned 3 m from the landing area at a height of 1 m above the floor (frontal and sagittal) recorded all trials. Video analysis of landing kinematics was performed to determine scores for each error item using the modified LESS. Itemized error scores for each patient were evaluated using an exploratory factor analysis, and factors were retained if eigenvalues were greater than 1.

Results: Our exploratory factor analysis yielded 2 factor groupings. The first factor (λ = 1.61) was comprised of 4 biplanar error items (ie, errors that occur in both the frontal and sagittal plane) that evaluated body segment positioning (eg, hip and knee flexion during landing). The second factor (λ = 1.02) was comprised of 2 errors occurring in the frontal plane that evaluated knee valgus and the overall impression of their landing strategy.

Conclusions: Reducing the modified LESS errors to 6-items could improve the efficiency and clinical utilization of the LESS in ACLR patients. An abbreviated version of the modified LESS may guide clinicians' decision making in gauging patients' readiness to return to play after ACLR.