Variability of insertion of the Achilles tendon on the calcaneus: an MRI study of younger subjects.

The insertional location of the Achilles tendon traditionally has been thought to be on the superior aspect of the calcaneus. This is based on descriptions and illustrations in anatomical textbooks. Our study is a digital magnetic resonance imaging (MRI) examination of the insertional location of the Achilles tendon in 69 subjects, 12 to 40 years of age. A midsagittal slice of the ankle was used to identify the most distal insertional location of the Achilles tendon on the posterior aspect of the calcaneus. The superior and inferior margins of the posterior aspect of the calcaneus were measured and the Achilles tendon insertion was calculated as a percentage of the total length of the posterior aspect of the calcaneus. Our results revealed that there is a statistically significant difference in the insertional location as related to age. Additionally, there is a statistically significant proximal migration (0.63%) of the insertional location with each advancing year. Based on our results, it appears that there is an inaccurate depiction in the anatomical literature, which may necessitate a change in the approach to pathologic conditions associated with the Achilles tendon.