Normative Achilles and patellar tendon shear wave speeds and loading patterns during walking in typically developing children

Anahid Ebrahimi; Robyn L Kuchler; Robin L Pomeroy; Isaac F Loegering; Jack A Martin; Darryl G Thelen

doi:10.1016/j.gaitpost.2021.05.023

Normative Achilles and patellar tendon shear wave speeds and loading patterns during walking in typically developing children

Gait Posture. 2021 Jul:88:185-191. doi: 10.1016/j.gaitpost.2021.05.023. Epub 2021 May 27.

Authors

Anahid Ebrahimi¹, Robyn L Kuchler¹, Robin L Pomeroy¹, Isaac F Loegering², Jack A Martin³, Darryl G Thelen⁴

Affiliations

¹ Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA.
² Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA.
³ Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA; Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, USA.
⁴ Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA. Electronic address: dgthelen@wisc.edu.

Abstract

Background: Motion analysis is commonly used to evaluate joint kinetics in children with cerebral palsy who exhibit gait disorders. However, one cannot readily infer muscle-tendon forces from joint kinetics. This study investigates the use of shear wave tensiometry to characterize Achilles and patellar tendon forces during gait.

Research question: How do Achilles and patellar tendon wave speed and loading modulate with walking speed in typically developing children?

Methods: Twelve typically developing children (9-16 years old) walked on an instrumented treadmill with shear wave tensiometers over their Achilles (n = 11) and patellar (n = 9) tendons. Wave speeds were recorded at five leg length-normalized walking speeds (very slow to very fast). Achilles and patellar tendon moment arms were measured with synchronized ultrasound and motion capture. The tendon wave speed-load relationship was calibrated at the typical walking speed and used to estimate tendon loading at other walking speeds.

Results: Characteristic Achilles and patellar tendon wave speed trajectories exhibited two peaks over a gait cycle. Peak Achilles tendon force closely aligned with peak ankle plantarflexor moment during pushoff, though force exhibited less modulation with walking speed. A second peak in late swing Achilles loading, which was not evident from the ankle moment, increased significantly with walking speed (p < 0.001). The two peaks in patellar tendon loading occurred at 12 ± 1% and 68 ± 6% of the gait cycle, matching the timing of peak knee extension moment in early stance and early swing. Both patellar tendon load peaks increased significantly with walking speed (p < 0.05).

Significance: This is the first study to use shear wave tensiometry to characterize Achilles and patellar tendon loading during gait in children. These data could serve as a normative comparison when using tensiometry to identify abnormal tendon loading patterns in individuals who exhibit equinus and/or crouch gait.

Keywords: Pediatric gait database; Shear wave tensiometry; Subject-specific calibration; Tendon force; Tendon stress.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Achilles Tendon*
Adolescent
Biomechanical Phenomena
Child
Gait
Humans
Patellar Ligament*
Tendinopathy*
Walking

Grants and funding

R01 HD092697/HD/NICHD NIH HHS/United States