The Twist of the Achilles Tendon - Associations of Torsions in the Lower Extremity.

Achilles tendinopathy and rupture of the Achilles tendon (AT) are frequent pathologies. Even though they may be associated with the twisted morphology of the AT, quantitative data on the extent of the twist of the entire AT are not available. The aim of this study was to investigate the torsion of the AT based on its individual parts and to evaluate a possible correlation with the torsion of the long bones of the lower extremity. Forty embalmed lower extremities were included in this study. The lateral deviation of the AT and its torsional angle as well as the angles of the individual parts in trans-section were measured. Thereafter, the torsions of femur and tibia were evaluated. Measuring the lateral deviation of the fibers resulted in an average torsion of the AT of 34.59° (SD 16.8°). The angles of the different parts of the AT in trans-section resulted in a median AT torsion of 15.73°, showing various patterns of rotations of the individual muscles. A statistically significant correlation between the torsions of the lower extremity and the AT (P =0.0242, r = 0.40) as well as a correlation between the femoral torsion and the AT torsion (P = 0.0127, r = 0.44) were found. This study adds to the morphological understanding of the torsion of the AT and its correlation with the torsions of the long bones of the lower extremity. Especially, the torsion of the femur seems to be connected to the torsion of the tendon. Clin. Anat., 2018. © 2018 Wiley Periodicals, Inc.