Influence of the torsion of femur and tibia on the torsion of the calcaneal tendon.

The vulnerability of the calcaneal tendon is favoured by pulling forces of different strengths within the calcaneal tendon, which result from its anatomical torsion. This trial tries to determine whether the torsion of femur and tibia influence the amount torsion of the Achilles tendon. Methods 40 lower extremities were measured. The torsion angle of femur and tibia and calcaneal tendon was measured. Descriptive data on the calcaneal tendon were gathered. Results The length of the Achilles tendon is 6,9 ± 2,6 cm, its diameter at the beginning of the insertion site is 2,8 ± 0.5 cm, compared to 3,8 ± 0.6 cm at the end of the insertion site. The overal mode of torsion of the calcaneal tendon was classified into 4 types. The torsion of the calcaneal tendon was positively correlated to the torsion of the femur (p<0.05, R=0.37). The tibial torsion did not influence the morphology of the calcaneal tendon significantly (p>0.05). Conclusion Generally, the torsion of the bones of the lower extremity as well as the torsion of the calcaneal tendon show a great amount of variation. But it seems, that the amount of femoral torsion influences the degree of torsion of the calcaneal tendon. Therefor not only the length of the calcaneal tendon, as already shown in literature, but also the bony configuration of the lower extremity influence the morphology of the calcaneal tendon. Based on the results of this study, a morphological analysis of the torsion of the calcaneal tendon and bone torsion could indicate higher or lesser risks of calcaneal tendon rupture.