Cross-sectional Area of the Achilles Tendon in a Cohort of Elite Military Warriors Using Standard Ultrasound Techniques

Abstract

Background: The prevalence of Achilles tendon (AT) pathology is common and can result in disability. Understanding normal AT properties can improve our ability to prevent AT injuries. We examined the cross-sectional area of the AT at multiple levels in an asymptomatic population of Army Rangers. Methods: This is a prospective cohort study composed of 41 voluntarily recruited United States Army Rangers deployed in a combat theater. All subjects were members of the Ranger Regiment participating in more than 20 h of intense bipedal non-sport weekly training with no history of AT pathology. While standing, each subject had bilateral AT calcaneal tuberosity insertions (0 cm) marked, along with skin markings made at 2 cm, 4 cm, and 6 cm superior to the AT insertion. AT diameter was measured at each level in the coronal and sagittal planes using ultrasound. Results: Mean sagittal diameter of the AT was 4.4 mm, 4.3 mm, 4.2 mm, and 3.9 mm at 0 cm, 2 cm, 4 cm, and 6 cm, respectively. Mean coronal diameter of the AT was 19.3 mm, 14.7 mm, 13.8 mm, and 14.5 mm at 0 cm, 2 cm, 4 cm, and 6 cm, respectively. The cross-sectional area was calculated as 0.66 cm2, 0.5 cm2, 0.46 cm2, and 0.44 cm2 at 0 cm, 2 cm, 4 cm, and 6 cm, respectively. Conclusion: Our data suggest that increased non-sport activity may not increase the cross-sectional area of the AT. Identifying the normal diameter at multiple levels throughout the most commonly injured area may improve the provider's ability to identify early disease processes and apply targeted interventions to help slow or prevent progression and possible rupture. Level of Evidence: Level III-V.