Preliminary study on acute effects of an intervention to increase dorsiflexion range of motion in reducing medial knee displacement

Abstract

BackgroundDynamic knee valgus, visually represented as medial knee displacement, is associated with anterior cruciate ligament injury. Recently, restrictions in ankle dorsiflexion range of motion have been associated with medial knee displacement. Therefore, interventions potentially increasing ankle dorsiflexion range of motion could alleviate medial knee displacement. The purpose of this pilot study was to explore the acute effects of an intervention to increase ankle dorsiflexion range of motion and reduce medial knee displacement in individuals who display medial knee displacement that is corrected with a heel lift. MethodsEight young participants who displayed medial knee displacement corrected with a heel lift completed a single-session intervention aimed at increasing dorsiflexion range of motion. Immediately before and after the intervention session, dorsiflexion range of motion in three static conditions (passive straight-knee, passive bent-knee, and weight-bearing lunge) and medial knee displacement during an overhead squat were assessed. FindingsThe single-session training program increased participants' dorsiflexion range of motion in all three static conditions (p = 0.0005 for straight-knee, 0.02 for bent-knee, and 0.01 for lunge) with moderate to large effect sizes (0.55–1.18). Additionally, the training resulted in a significant reduction in medial knee displacement during the overhead squat (p = 0.02). InterpretationThe finding indicate that our interventional protocol appears beneficial in increasing dorsiflexion range of motion among individuals with medial knee displacement. Additionally, improving dorsiflexion range of motion may be a promising direction for reducing medial knee displacement, which is a risk factor for anterior cruciate ligament injury.