7 131 Normative Ultrasound Values for Achilles Tendon Thickness: An International Study Table 3. Estimates of the normative median (50th), lower (2.5th) and upper (97.5th) percentile values (upper, lower) of Achilles tendon thickness for the midportion and insertional part of the tendon, presented by sex for each decade of life. Estimates are for individuals with a body mass index of 24.0 kg/m2 and a height of 183 cm (males) or 170 cm (females) Age (years) Male Female Midportion Insertion Midportion Insertion 20 4.9 (4.1, 6.0) 3.7 (3.0, 4.8) 4.4 (3.1, 5.6) 3.3 (2.8, 4.2) 30 5.1 (4.2, 6.4) 3.8 (3.0, 4.9) 4.6 (3.2, 6.0) 3.4 (2.8, 4.4) 40 5.3 (4.4, 6.8) 3.9 (3.1, 5.1) 4.8 (3.3, 6.4) 3.5 (2.9, 4.5) 50 5.5 (4.5, 7.2) 4.0 (3.1, 5.2) 5.0 (3.5, 6.8) 3.6 (3.0, 4.7) 60 5.7 (4.6, 7.6) 4.1 (3.2, 5.4) 5.2 (3.6, 7.2) 3.7 (3.0, 4.8) 70 5.9 (4.7, 8.0) 4.2 (3.3, 5.6) 5.4 (3.7, 7.6) 3.8 (3.1, 5.0) 80 6.2 (4.8, 8.4) 4.3 (3.3, 5.7) 5.6 (3.8, 8.0) 3.9 (3.1, 5.2) Difference between asymptomatic individuals and patients with Achilles tendinopathy Patients with AT were on average older, taller, had a higher BMI and a lower physical activity level than the asymptomatic participants (Table 1). Maximum tendon thickness as measured with UTC is also displayed in Table 1. The mean difference (95%CI) in tendon thickness, adjusted for age, sex, height, BMI and physical activity level, between the asymptomatic population and AT patients was 2.7 mm (2.3-3.2, p<0.001) for the midportion and 1.4 mm (1.1-1.7, p<0.001) for the insertional region. Using the normative equations for the median, lower (2.5th) and upper (97.5th) values of tendon thickness for each AT patient, we found that 73/100 patients (73%) had increased tendon thickening (a value larger than the 97.5th percentile). DISCUSSION In this large international cross-sectional study, we demonstrated that Achilles tendon thickness is influenced by personal characteristics. We found that age and height had the largest influence on maximum anterior-posterior distance. The mean difference in tendon thickness between asymptomatic persons and patients with Achilles tendinopathy was 2.7 mm for the midportion region and 1.4 mm for the insertional region. The majority of the AT patients (73%) had an increased tendon thickening outside the 95% reference interval. This study presents novel reference values for the thickness of the midportion and insertional region of the Achilles tendon, which have been lacking in the literature. Currently, maximum Achilles tendon thickness is estimated at 6 to 7 mm based on clinical experience and cross-sectional studies.13-15 These studies have reported a considerable deviation surrounding the normative values for Achilles tendon thickness in selected (e.g.
RkJQdWJsaXNoZXIy MTk4NDMw