Effects of foot orthoses on ankle kinematics in male runners with Achilles tendinopathy

Introduction: Achilles tendinopathy (AT) is a common injury among male runners, affecting the longevity of sporting careers and participation in exercise. Abnormal rearfoot biomechanics are thought to be risk factors for AT, but their role is not well established. There is evidence to suggest that people with AT have altered eversion kinematics at the rearfoot, which may result in disproportionate loading across the medial and lateral aspects of the Achilles tendon. Altered ankle dorsiflexion mechanics have also been discussed as a cause of AT, where the tendon may be placed under a greater load in the sagittal plane. The purpose of this study was to evaluate the immediate eversion and dorsiflexion kinematic and kinetic effects of foot orthoses in runners with AT.
Methods: Thirteen adult males (age 42 yr ± 10, weight 78 kg ± 12, height 178 cm ± 6) with midportion AT symptoms, running > 20 kilometres per week, were recruited. Confirmation of AT pathology was performed using diagnostic ultrasound. Three dimensional kinematic and kinetic data were collected using a Vicon motion analysis system and AMTI force plates during the stance phase of shod running gait for two conditions: i) with prefabricated semi-rigid foot orthoses, and ii) no orthoses. Each participant completed at least five overground running trials per condition at a controlled running speed. Data processing was completed in Workstation and BodyBuilder software to determine: peak rearfoot eversion angle, rearfoot eversion excursion, peak ankle dorsiflexion angle, peak plantarflexion moment and plantarflexion impulse. Statistical analyses were performed using a paired samples t-test with SPSS software (version 19). An alpha level of 0.05 was set.
Results: The ankle eversion excursion was significantly reduced with use of foot orthoses (11.9 deg ± 4.3) compared to footwear-only (13.4 deg ± 4.3; p = 0.03). No differences between conditions were observed for the other variables (p > 0.05).
Discussion: Our data demonstrate that the immediate use of foot orthoses reduces rearfoot eversion motion in male runners with midportion AT during the stance phase of running. This change results in kinematic parameters similar to those in asymptomatic runners, which may have a beneficial treatment response. Other elements of frontal and sagittal plane mechanics were not altered. Further studies are required to evaluate the long term biomechanical effects of foot orthoses in people with AT and its role in improving pain and function outcomes across both genders.

Abstract only.