Poster D4 - Pilot study investigating sex differences in minimum Achilles tendon cross-sectional area normalized by triceps surae muscle volume and subject anthropometry

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Remy Brettell (he/him/his)

Undergraduate Researcher
University of Virginia
Lorton, Virginia, United States

Co-Author(s)

EM

Emily McCain

Postdoctoral Research Scientist
University of Virginia, United States

Primary Investigator(s)

SB

Silvia Blemker

Professor of Biomedical Engineering
University of Virginia, United States

Introduction: There are many influencing factors on triceps surae and Achilles tendon structure, such as age, height, weight, exercise, and prior injuries, that have been investigated recently through in vivo techniques (Handsfield et al. 2014). However, the impact of sex on this musculotendon complex has not been thoroughly investigated. Studies typically focus on differences in the triceps surae muscles or Achilles tendons of men and women, and often have disproportionately more male subjects (Rosso et al. 2012). Achilles tendon injuries typically occur 2-6cm proximal of the calcaneal insertion where the tendon cross-sectional area (CSA) is smallest, and these injuries are more common in males (Vosseller et al. 2013). Interestingly, minimum Achilles tendon CSA correlates with body size and tibia length (Rosso et al. 2012), and males tend to have larger Achilles tendon CSAs than females (Intziegianni et al. 2017). Sex differences in the proportionality between muscle volume or body size and minimum tendon CSA could explain increased incidence in Achilles tendon injury occurring in males. This preliminary work will investigate the impacts of sex, triceps surae muscle volume, and height on minimum Achilles tendon CSA.

Materials and

Methods: Subjects laid supine during a two-point Dixon sequence with field of view: 280 mm x 450 mm, slice thickness: 5 mm, and in plane spatial resolution: 1.1 mm x 1.1 mm, 3T MRI scanner (Trio, Siemens, Munich Germany) to identify muscle and tendon boundaries. This scan allowed for volume calculations of muscle through a deep convolution neural network-based segmentation method (Ni et al. 2019), and manual vetting (Springbok Analytics, Charlottesville, VA). Achilles tendons were segmented manually in 3D Slicer starting at calcaneal insertion and continuing above the soleus insertion. Tendon geometry origins were set at the segmentation center of mass, and coordinate axes of centralized geometries were defined by principal inertial axes. CSAs along the tendon length at 1mm intervals were quantified and the minimum CSA was identified. Paired t-tests were used to compare minimum Achilles tendon CSAs normalized by triceps surae muscle volume, tibial length, and height between male and female populations.

Results, Conclusions, and Discussions: Minimum Achilles tendon CSAs were plotted against triceps surae muscle volume (Fig 1A), tibial length (Fig 1B), and subject height (Fig 1C). T-tests revealed no significant sex differences (α > 0.05) on normalized CSA data, and no visible correlations were noted between subjects or sexes, possibly due to the small sample. Our future work includes expanding this pilot data to 20 male and 20 female subjects and reassessing conclusions drawn from the initial dataset. We will also quantify the ratio of minimum Achilles tendon CSA to foot length to approximate geometric factors that affect the ankle torque generated during pushoff. The ratio of triceps surae and Achilles tendon lengths between males and females will also be considered to potentially inform differences in tendon loading.

Acknowledgements (Optional):