Altering the Foot Progression Angle During Gait: Effects in Kinematics and Estimated Knee Joint Loading
L.A. Torsij (TU Delft - Mechanical Engineering)
J. Harlaar – Mentor (TU Delft - Mechanical Engineering)
Erin Macri – Mentor (Erasmus MC)
A. Seth – Graduation committee member (TU Delft - Mechanical Engineering)
M.G.H. Wesseling – Mentor (TU Delft - Mechanical Engineering)
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Abstract
Background
Altering the foot progression angle (FPA) is a commonly researched approach to reduce the knee adduction moment (KAM) in patients with medial compartment knee osteoarthritis. However, little is known about kinematic strategies used to achieve specific FPAs, and the effect of different FPAs on the medial tibiofemoral contact force (TFCF).
Objective
This study aimed to investigate how walking with different FPAs affects lower-limb joint angles and medial TFCF, to assess whether a personalized target FPA can reduce medial TFCF, and to investigate the relationship between changes in KAM and changes in medial TFCF.
Methods
Motion capture data were recorded for healthy participants while walking with their natural FPA, as well as walking with four altered FPA conditions (toe-out and toe-in 5° and 10°, relative to the natural FPA). For each condition, the KAM was calculated using ground reaction forces and motion capture data, and joint angles and medial TFCF were obtained by performing musculoskeletal modeling. Peak values during the first and second part of the stance phase, as well as the area under the curve during stance phase (impulse), were extracted for the KAM and medial TFCF.
Results
Fourteen healthy participants (9 women, age: 57.8 ± 12.1 years) were included. Across all joint angles, changes for toe-out conditions occurred in opposite directions from toe-in conditions, with larger differences for 10° than 5° conditions. Hip rotation differed significantly throughout the stance phase, subtalar inversion/eversion showed significant differences during late stance. Changes in medial TFCF varied across FPA conditions without a consistent pattern. The personalized target FPA significantly reduced first peak (-0.22 ± 0.19 body weight (BW), p = 0.002), second peak (-0.23 ± 0.32 BW, p = 0.049), and impulse (-0.15 ± 0.13 BW, p = 0.002) medial TFCF. Changes in KAM were more strongly associated with changes in medial TFCF for the first peak during toe-out gait (R\textsuperscript2 = 0.64 and 0.82 for 5° and 10°, respectively) and for the second peak during toe-in gait (R\textsuperscript2 = 0.44 and 0.76 for 5° and 10°, respectively).
Conclusions
Lower-limb joint angles were consistently altered for different FPA conditions, with the largest changes observed in hip rotation and subtalar inversion/eversion. The change in medial TFCF for FPA alterations was highly individual, with no consistent pattern across participants. A personalized target FPA significantly reduced medial TFCF throughout the stance phase. The relationship between changes in KAM and medial TFCF was dependent on stance phase, consistent with prior research, and also varied across FPA conditions.
Studies including patients with knee osteoarthritis are needed to determine how FPA alterations influence medial compartment loading in the target population.