Comment on "Inter-examiner and inter-day reliability of dynamic tibiofemoral movements measurement using motion capture during walking and jumping tasks".

Abstract

Reliable quantification of dynamic anterior tibia translation and internal tibia rotation is essential for advancing anterior cruciate ligament research beyond static clinical assessments. While optoelectronic motion capture combined with functional calibration techniques has been proposed as an accessible approach, evidence regarding its robustness across examiners, days, and task demands remains limited. This commentary aims to critically appraise the methodological and translational implications of recently reported reliability estimates for dynamic tibiofemoral measurements during walking and jump-landing tasks. A focused methodological evaluation was undertaken, examining the analytical framework used to assess inter-examiner and inter-day reliability, the interpretation of time-series intraclass correlation coefficients and standard error of measurement, and the alignment of these metrics with clinically meaningful inference. Particular attention was paid to task dependency, biological versus methodological variability, and the relevance of reliability estimates across different phases of movement. The reported findings indicate generally good-to-excellent reliability for dynamic tibiofemoral measures, with superior consistency during high-load phases of jump landings. However, reliance on pointwise time-normalized metrics may obscure phase-specific variability, and relative error estimates expressed as percentages of range of motion lack direct clinical anchoring. Differences between inter-examiner and inter-day reliability further suggest sensitivity to behavioral and task-execution factors that were not formally quantified. The evaluated approach represents an important step toward accessible assessment of dynamic knee stability. Future studies may benefit from integrating event-based reliability metrics, contextualizing measurement error against clinically relevant thresholds, and accounting for variability in movement strategy to enhance translational applicability in anterior cruciate ligament research.