Authors: Alon Rabin, DPT, PhD

Study Design
Cross-sectional.

Background
Altered hip and knee kinematics have been associated with several knee disorders including anterior cruciate ligament tear, patellofemoral pain, and iliotibial band syndrome. Limited ankle dorsiflexion (DF) range of motion (ROM), which has been linked with some of these disorders, has also been associated with altered knee kinematics.

Objective
Explore the association of ankle DF ROM with hip and knee kinematics during a step down task.

Methods
Thirty healthy participants underwent a 3-dimensional analysis of hip and knee kinematics during a lateral step down test, followed by measurement of ankle DF ROM in weight-bearing (WB) and non-weight-bearing (NWB). Participants were dichotomized using the median values into low- and high-DF subgroups within both WB and NWB. Hip and knee kinematics were compared between the low- and high-DF subgroups.

Results
Participants in the low-DF subgroups exhibited greater peak hip adduction (WB, P=.01; NWB, P<.01) and greater peak knee external rotation (WB, P=.01; NWB, P<.01) compared with participants in the high-DF subgroups. In addition, participants in the low-DF WB subgroup exhibited decreased peak knee flexion compared with participants in the high-DF WB subgroup (P<.01). Conclusion Individuals with a less ankle DF ROM exhibited hip and knee kinematics previously associated with several knee disorders suggesting this impairment may be involved in the pathogenesis of the same disorders. Assessment of ankle DF ROM may be useful as part of a pre-participation screening. Furthermore, deficits in ankle DF ROM may need to be addressed in individuals with altered movement patterns. J Orthop Sports Phys Ther, Epub 29 Sep 2016. doi:10.2519/jospt.2016.6621