The effect of reduced ankle dorsiflexion on lower extremity mechanics during landing: A systematic review

Abstract

Objectives

To examine the evidence for effect of restricted ankle dorsiflexion range of motion on lower-extremity landing mechanics.

Design

Literature review.

Methods

Systematic search of the literature. Articles critiqued by two reviewers.

Results

Six studies were identified that investigated the effect of restricted DF ROM on landing mechanics. Overall, results suggest that landing mechanics are altered with restricted DF ROM, but studies disagree as to the particular mechanical variables affected.

Conclusions

There is evidence that restricted dorsiflexion range of motion may alter lower-extremity landing mechanics in a manner, which predisposes athletes to injury. Interpretation of results was made difficult by the variation in landing tasks investigated and the lack studies investigating sport-specific landing tasks. The focus of studies on specific mechanical variables rather than mechanical patterns and the analysis of pooled data in the presence of different compensation strategies between participants also made interpretation difficult. These areas require further research.

Introduction

Many lower-limb injuries are associated with restricted ankle dorsiflexion (DF) range of motion (ROM)1, 2, 3, 4, 5, 6, 7, 8 such as ACL,⁷ Achilles,⁴ and patellar tendon injuries.1, 8 In New Zealand from July 2012−June 2013, the Accident Compensation Corporation (ACC) received 172,461 new claims for lower-extremity injuries incurred during sport with costs exceeding $15 million NZD.⁹ Ankle injury sustained during sports participation may contribute to injury risk as reduced DF ROM has been reported following ankle sprain,¹⁰ ankle ligament reconstruction,¹¹ chronic ankle instability,12, 13 and with ankle bracing.12, 13

There are a number of theories as to the mechanics behind the association between DF restriction and injury. Reduced DF may restrict the ability to pass the leg forwards over the foot6, 14, 15, 16 and to lower the centre of mass during squat-type movements.¹⁷ This may be compensated for via subtalar and midfoot pronation6, 14, 15 or knee valgus6, 18 both of which have been linked to chronic and acute injury.19, 20, 21, 22, 23 This theory is supported by studies reporting increased knee valgus during squat movements in participants with reduced DF ROM.16, 18

DF restriction may also increase injury risk by altering lower-extremity stiffness and landing forces. Decreased stiffness on landing results in greater lower-extremity joint-excursion and thereby reduces loading-rate (LR) and ground-reaction forces (GRFs).24, 25 Restricted DF and the associated reduction in hip and knee flexion24, 26 could therefore increase GRFs or LRs as the reduced joint excursion causes increased stiffness.26, 27 Increased injury risk has been reported with both higher GRFs28, 29, 30 and higher LRs.27, 31, 32 A further possibility is that DF loss is linked to injury via one of a number of compensatory mechanical patterns rather than through a single compensatory movement at a particular joint. Dynamical Systems theory approaches goal-directed movement from the perspective that there are multiple biomechanical degrees of freedom (DOF), which work in different patterns to achieve a consistent outcome.33, 34 This variation in biomechanical patterns is termed ‘coordinative variability’ and the pattern used for a given task can vary widely both within and between individuals.33, 34 Restricted DF may represent a loss of DOF and force individuals into one of a number of alternative movement patterns that may be associated with various injuries. A measure such as stiffness which captures a number of variables into a single measure may be more beneficial for identifying changes in movement patterns than individual mechanical variables.

Identifying predisposing factors to injury and the mechanical factors linked to increased injury risk will assist clinicians in prevention and treatment of injury. Given the above variation in rationale for a link between reduced dorsiflexion and injury incidence, the purpose of this review is to examine the evidence for the effect of DF ROM on peak DF angle, ankle, knee, and hip kinematics, peak vGRF, LR, time-to-peak (TTP) vGRF, and stiffness during landing.