Functional anatomy, histology and biomechanics of the human Achilles tendon — A comprehensive review

Winnicki, Kamil; Ochała-Kłos, Anna; Rutowicz, Bartosz; Pękala, Przemysław A.; Tomaszewski, Krzysztof A.

doi:10.1016/j.aanat.2020.151461

Cited by 63 publications

(61 citation statements)

References 117 publications

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“…In our study, the maximum thickness of the normal free Achilles tendon was found to range between 3.9 and 5.9 mm and to be larger in males, in agreement to previous reports also reporting 6 cm as a cut-off point to discriminate a normal from an abnormally enlarged tendon [5,9,23,25,32]. In a previous MRI study on a population aged 18-70 years old, the normal Achilles tendon's thickness was 6.1-7.1 mm [11].…”

Section: Discussionsupporting

confidence: 92%

The anatomical variant of high soleus muscle may predispose to tendinopathy: a preliminary MR study

Drakonaki¹,

Gataa

Szaro

2021

Surg Radiol Anat

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Purpose This study aimed to examine the anatomic variations at the level of the distal soleus musculotendinous junction and the possible association between the length of the free tendon and the development of symptomatic Achilles tendinopathy. Methods We retrospectively assessed 72 ankle MRI studies with findings of Achilles tendinopathy (study group, 26 females/46 males, mean age 52.6 ± 10.5 years, 30 right/42 left) and 72 ankle MRI studies with normal Achilles tendon (control group, 32 females/40 males, mean age 35.7 ± 13.7 years, 42 right/30 left side). We measured the distance from the lowest outline of the soleus myotendinous junction to the proximal outline of the Achilles tendon insertion (length of the free tendon, diameter a) and to the distal outline of the insertion (distance B). We also measured the maximum thickness of the free tendon (diameter c) and the distance between the levels of maximum thickness to the proximal outline of the Achilles tendon insertion (distance D). All measurements were assessed twice. Statistical analysis was performed using independent t test. Results Distances A and B were significantly larger in tendinopathic tendons (59.7 and 83.4 mm, respectively) than normal Achilles tendons (38.5 and 60.8 mm, respectively) (p = 0.001). Mean distance C was larger in tendinopathic than normal tendons (11.2 versus 4.9 mm). Distances C and D were significantly larger in males than females. There was no significant difference in the measurements between sides. Conclusion There is wide anatomical variation in the length of the free Achilles tendon. Tendinopathy may be associated with the thicker free part of the Achilles tendon. The anatomical variant of the high soleus musculotendinous junction resulting in a longer free Achilles tendon may be a predisposing factor to the development of tendinopathy.

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Section: Discussionsupporting

confidence: 92%

The anatomical variant of high soleus muscle may predispose to tendinopathy: a preliminary MR study

Drakonaki¹,

Gataa

Szaro

2021

Surg Radiol Anat

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“…We studied the Achilles tendon between the lower outline of the soleus muscle belly to the level of the calcaneal tuber, which includes the zone where tendinopathy and ruptures most often occur 2 , 8 , 22 . Active tracking of the subtendons from the myotendinous junction, distal to the calcaneus, showed the same twisted structure of the Achilles tendon as revealed previously 5 , 10 , 17 , 18 , 20 , 23 . Most often it was possible to determinate the subtendon originating from the lateral head of the gastrocnemius muscle.…”

Section: Discussionsupporting

confidence: 78%

“…Most of the previous studies assessing the internal structure of the Achilles tenon were conducted on cadavers 4 , 5 , 16 – 20 and very few in ultrasound 8 . We think that our study is necessary due to the fact that MRI is a modern method of imaging the musculoskeletal and an excellent tool for assessing the Achilles tendon anatomy 4 , 5 , 21 . We noticed that the possibility of identifying the subtendons on MRI is not as clear as during an anatomical dissection and classical anatomy of the Achilles tendon is significantly different from then radiological anatomy.…”

Section: Discussionmentioning

confidence: 99%

“…The Achilles tendon subtendons initially run vertically, corresponding to the position of the muscle bellies. In the midportion of the tendon, a clear rotation is observed so that subtendon from the lateral head of the gastrocnemius muscle (S-LGC) is found in the anterior part while subtendon from the medial head (S-MGC) in the posterior part of the tendon 4 , 5 . The subtendon from the soleus muscle (S-Sol), which is a prolongation of the soleus central tendon (T-Sol) 6 – 9 is located in the medial and anterior part of the tendon.…”

Section: Introductionmentioning

confidence: 99%

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Distribution of the subtendons in the midportion of the Achilles tendon revealed in vivo on MRI

Szaro

Ramirez

Borkmann

et al. 2020

Sci Rep

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The aim of the study was to check if the subtendons of the Achilles tendon can be identified in vivo on MRI in the midportion of the tendon. The relation of the plantaris tendon to the Achilles tendon was also examined. A retrospective study of 200 MRI of ankle joints including the Achilles tendon was conducted. Statistical analysis of the correlation between the possibility of identifying the subtendons and the side, gender, presence of the central soleus tendon and plantaris tendon variation was performed. The inter-observer agreement between two reviewers in their evaluation of the subtendons was assessed using kappa statistics. The subtendon from the lateral head of the gastrocnemius muscle was identified in 65% (k = 0.63) and was located in the anterior part of the Achilles tendon. The subtendon from the soleus muscle was recognized in 12% (k = 0.75) comprising anterior part of the tendon. In 6% the subtendon from the medial head of the gastrocnemius muscle was identified (k = 0.58). The central soleus tendon was identified in 85% of cases. Statistical analysis shows the weak correlation of the presence of the central soleus tendon and the possibility of identifying the subtendon from the soleus muscle. The plantaris tendon was directly related to the insertion of the Achilles tendon in 42.5%. Identification of the subtendons of the Achilles tendon on MRI is challenging, and most often it is only possible to find the subtendon of the lateral head of the gastrocnemius muscle.

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“…For example, higher amounts of cartilage cells and cartilage matrix proteins were produced in AT0 cm, which could result in a stiffer tendon structure ( Maffulli et al, 2006 ; Bah et al, 2016 ), whereas the increase in abnormal tenocytes and type III collagen in AT3 cm could reduce the ability of tendon tissue to resist tensile forces ( Ooi et al, 2015 ). In addition, considering the rotatory anatomy and multiple muscles of the AT, it can be assumed that a difference in AT composition has an impact on the non-uniform behavior of the different regions in the AT ( Winnicki et al, 2020 ). Furthermore, AT0 cm is directly attached to the calcaneus so that it suffers more load-bearing strain than other regions ( Zwirner et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Elasticity of the Achilles Tendon in Individuals With and Without Plantar Fasciitis: A Shear Wave Elastography Study

et al. 2021

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The elastic properties of the Achilles tendon (AT) are altered in local injury or other diseases and in response to changes in mechanical load. Recently, elastography has been used to evaluate variations in tendon elastic properties, mainly among healthy individuals or athletes. Therefore, this study evaluated the biomechanical changes in ATs in individuals with and without plantar fasciitis (PF). The purposes were as follows: (1) to evaluate the passive stiffness of three regions of the AT which defined as 0 (AT0 cm), 3 (AT3 cm), and 6 cm (AT6 cm) above the calcaneal tuberosity in participants with and without PF, (2) to investigate the interplay between the passive stiffness in patients with PF and pain, (3) to detect optimal cut-off points of stiffness of the AT in assessing individuals with chronic PF, and (4) to determine the correlation between the plantar fascia thickness (PFT) and pain. This cross-sectional study included 40 participants (mean age = 51 ± 13 years). When the ankle was in a relaxed position, patients with PF experienced increased passive stiffness in AT0 cm (p = 0.006) and AT3 cm (P = 0.003), but not in the neutral position. Significant correlations were observed between pain and stiffness of AT (AT0 cm r = 0.489, P = 0.029; AT3 cm r = 487, P = 0.030; AT6 cm r = 0.471, P = 0.036), but not in the PFT (P = 0.557). Optimal cut-off stiffness was AT (452 kPa) in the relaxed ankle position. The plantar fascia of patients with PF was significantly thicker than that of the controls (P < 0.001). Findings from the present study demonstrate that tendon stiffness is a good indicator of the clinical situation of patients with PF. Monitoring passive tendon stiffness may provide additional information to assess severity of the condition and guide therapeutic. The treatment programs for PF should also be tailored to the distal AT, as conventional therapy might not be targeted to tight tendons.

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Functional anatomy, histology and biomechanics of the human Achilles tendon — A comprehensive review

Cited by 63 publications

References 117 publications

The anatomical variant of high soleus muscle may predispose to tendinopathy: a preliminary MR study

The anatomical variant of high soleus muscle may predispose to tendinopathy: a preliminary MR study

Distribution of the subtendons in the midportion of the Achilles tendon revealed in vivo on MRI

Elasticity of the Achilles Tendon in Individuals With and Without Plantar Fasciitis: A Shear Wave Elastography Study

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