Achilles tendon injuries may be classified as noninsertional or insertional. The former group includes a rupture 2-6 cm above the insertion of the tendon on the calcaneus. The latter group includes insertional Achilles tear, which may be associated with Haglund deformity of the calcaneus. Majority of individuals who sustain Achilles tendon injury are men. The diagnsosis can often be made by physical examination. However, up to 25% of patients with partial or complete Achilles tear may be misdiagnosed based on physical exam findings alone. MR imaging findings confirm the diagnosis particularly in questionable cases.
Sag STIR
Ax GRE
Ax PD Fat Sat
46 yo with basketball injury 6 wks ago
The Achilles tendon is formed by the union of the tendons of the gastrocnemius and soleus muscles and inserts on the posterior aspect of the calcaneus. It is not invested by a synovial sheath, but is surrounded by loose connective tissue referred to as the peritenon.
Spontaneous Achilles tendon rupture or partial tears typically occur in otherwise healthy, relatively young patients (third to fifth decade of life), with no history of heel or calf pathology. Majority of individuals who sustain Achilles tendon injury are men. The mechanical cause of the injury is most commonly active, forceful plantar flexion. Achilles tendon injuries may be classified as noninsertional or insertional. The former group includes a rupture 2-6 cm above the insertion of the tendon on the calcaneus. The latter group includes insertional Achilles tear, which may be associated with Haglund deformity of the calcaneus.
The diagnsosis can often be made by physical examination. However, up to 25% of patients with partial or complete Achilles tear may be misdiagnosed based on physical exam findings alone. MR imaging findings confirm the diagnosis particularly in questionable cases. Partial Achilles tendon tears demonstrate heterogeneous signal intensity and thickening of the injured tendon without complete interruption. Edema manifested as increased T2 signal will usually be present within the tendon, subcutaneous tissues, and in Kager's fat pad. Hemorrhage signal may also be present in those structures and signal characteristics will vary according to the age of the injury. Complete Achilles rupture manifests as discontinuity of the tendon with fraying and retraction of the torn edges. In acute ruptures, the gap between the rupture will have intermediate T1 signal and high T2 signal due to edema and acute hemorrhage. In chronic ruptures, scar or fat signal will usually predominate.
Suggested Reading:
Rosenberg ZS, Beltran J and Bencardino JT. MR imaging of the ankle and foot. Radiographics, 2000; 20:S153-S179
Weinstabi R, Stiskal ZM, Neuhold A, Aamlid B, Hertz H. Classifying calcaneal tendon injury according to MRI findings. J Bone Joint Surg [Br] 1991; 73:683-685.
Hartgerink P, Fessell DP, Jacobson JA and van Holsbeeck MT. Full- versus Partial-Thickness Achilles Tendon Tears: Sonographic Accuracy and Characterization in 26 Cases with Surgical Correlation. Radiology. 2001;220:406-412.
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