Article

Ultrasonography has been widely applied for in vivo measurements of
tendon mechanical properties. Assessments of human Achilles tendon mechanical
properties have received great interest. Achilles tendon injuries predominantly
occur in the tendon region between the Achilles-soleus myotendinous junction and
Achilles-calcaneus osteotendinous junction i.e. in the free Achilles tendon.
However, there has been no adequate ultrasound based method for quantifying the
mechanical properties of the free human Achilles tendon. This study aimed to: 1)
examine the mechanical properties of the free human Achilles tendon in vivo by
the use of ultrasonography and 2) assess the between-day reproducibility of these
measurements. METHODS: Ten male subjects had the Achilles tendon moment arm
length, Achilles tendon cross sectional area and free Achilles tendon length
determined. All subjects performed isometric plantarflexion ramp contractions to
assess between-day reproducibility on two separate days. Simultaneous
ultrasonography based measurements of Achilles-soleus myotendinous junction and
Achilles-calcaneus osteotendinous junction displacement together with Achilles
tendon force estimates yielded free Achilles tendon mechanical properties.
FINDINGS: Free Achilles tendon maximal force, deformation and stiffness were 1924
(SD 229) N, 2.2 (SD 0.6) mm and 2622 (SD 534) N/mm on day 1. For between-day
reproducibility there were no significant differences between days for free
Achilles tendon mechanical properties. The between-day correlation coefficient
and typical error percent were 0.81 and 5.3% for maximal Achilles tendon force,
0.85 and 11.8% for maximal Achilles tendon deformation and 0.84 and 8.8% for
Achilles tendon stiffness respectively. Last, osteotendinous junction proximal
displacement on average contributed with 71 (SD 12) % of proximal myotendinous
junction displacement. INTERPRETATION: This study, for the first time, presents
an ultrasonography based in vivo method for measurement of free AT mechanical
properties. The method is applicable for evaluation of free human Achilles tendon
mechanical properties in relation to training, injury and rehabilitation.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS