Publications

• This research provides characteristics of the Achilles tendon in senior badminton players.
• Operated Achilles tendons are thicker and wider than non-injured tendons.
• Achilles surgery causes an asymmetry between operated and non-injured tendons.
• An increase in the logarithmic decrement value could be an indicator of the risk of injury.

Background: The aim of this study was to describe the differences in structural and mechanical properties between operated and non-injured Achilles tendons in senior badminton players who had had Achilles tendon surgery and had returned to play.

Methods: Eighteen players (age = 48.9(10.0)years), assigned to the unilateral Achilles tendon rupture group and 177 non-injured players (age = 55.4(9.4)years), assigned to the control group. A Logiq®S8 ultrasound was used to study tendon structure and elastography index values and a Myoton®PRO hand-held myotonometer was used to record the stiffness of the Achilles tendon.

Findings: In Achilles tendon rupture group, operated tendons showed higher values than non-injured ones in thickness (Operated = 9.03(2.67)mm vs. non-injured = 5.88(0.88)mm; P < 0.001), width (Operated = 18.44(3.20)mm vs. non-injured = 16.80(1.97)mm; P = 0.039), cross sectional area (Operated = 140.33(60.29)mm2 vs. non-injured = 74.40(17.09)mm2; P < 0.001) and elastography index (Operated = 2.05(1.35)A.U. vs. non-injured = 1.47(0.62)A.U.; P = 0.025). The bilateral differences shown by the Achilles tendon rupture group were greater than the bilateral differences shown by the control group for thickness (P < 0.001), width (P = 0.001), cross sectional area (P < 0.001), tone (P = 0.006) and dynamic stiffness (Achilles tendon rupture group = 10.85(23.90)N/m−1. vs. control group = 0.18(18.83)N∙m−1; P = 0.031).

Interpretation: Surgery on the Achilles tendon and adaptation to the mobilisation and strength training during rehabilitation could provoke structural and mechanical differences compared to the non-injured tendon. Furthermore, the differences between both Achilles tendons in the Achilles tendon rupture group was higher than the asymmetry observed between dominant and non-dominant Achilles tendons in the control group. In addition, the higher logarithmic decrement values showed by non-injured tendons in the Achilles tendon rupture group could be a tendinous injury risk factor.

Keywords: Badminton, Elastography, Achilles tendon, Myotonometer, Ultrasound

In conclusion, operated Achilles tendons were thicker, wider, stiffer and with greater CSA than non-injured Achilles tendons after five years of returning to play. The differences in the ATR group tendons showed an asymmetric pattern between operated and non-injured tendons greater than the asymmetry shown by non-injured players. The higher logarithmic decrement values showed by non-injured tendons in the Achilles tendon rupture group could be a tendinous injury risk factor. Further studies are warranted to understand the difference between Achilles operated and recovered tendons in badminton players and sedentary people regarding structural and mechanical properties.