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Well delineated hypo-echogenic area in the musculotendinous junction of the Achilles tendon and early emergence of soleus muscle on musculoskeletal ultrasound
Well delineated hypo-echogenic area in the musculotendinous junction of the Achilles tendon and early emergence of soleus muscle on musculoskeletal ultrasound

Tear of the musculotendinous junction of an achilles tendon

Thanks to Rob Mast, Extended Scope Physiotherapist for this interesting case...

This patient was a 30 year old male. He ran up the steps at a tube station and felt a sudden pulling sensation in the lower calf.  He then struggled to walk for several days, with a sharp pain and tightness.

(Ref Asplund,C. & Best, T. (2013) Achilles tendon disorders, British Medical Journal .

Two days following the injury there was a well delineated hypo-echogenic area in the musculotendinous junction of the  Achilles tendon and early emergence of soleus muscle on musculoskeletal ultrasound (Figure 1). This finding was discussed with two experienced musculoskeletal ultrasound specialists.  As this was such a well defined and small area, the initial feeling was this might be a small pre-existing cystic defect in the tendon. However closer analysis clearly shows a distinctive delineation of the musculotendinous junction (MTJ) which is only seen by a hypo-echogenic line extending from the periphery of the focal defect. This was consistent with a tear of the musculotendinous junction of achilles tendon. If the injury had been more severe it would have almost certainly lead to a  separation of the MTJ to a greater or lesser degree and resulted in separation of the muscle complex at MTJ

Well delineated hypo-echogenic area in the musculotendinous junction of the Achilles tendon and early emergence of soleus muscle on musculoskeletal ultrasound
Figure 1: Ultrasound 2 days after injury, demonstrating well delineated hypo-echogenic area in the musculotendinous junction of the Achilles tendon and early emergence of soleus muscle on musculoskeletal ultrasound

A repeat musculoskeletal ultrasound scan was performed two weeks later and clearly there is a increase in hyper-echogenicity in the defect making it less dark and the periphery starting to resemble the surrounding echo-texture of fibres (Figure 2).

Ultrasound at 2 weeks with an increase in hyper-echogenicity in the defect making it less dark and the periphery starting to resemble the surrounding echo-texture of fibres

Figure 2: Ultrasound at 2 weeks with an increase in hyper-echogenicity in the defect making it less dark and the periphery starting to resemble the surrounding echo-texture of fibres

This is much more advanced at 5/52 when it is almost difficult to find the defect as it has more or completely filled in.

Figure 3: Ultrasound at 5 weeks, demonstrating filled lesion with new tissue
Figure 3: Ultrasound at 5 weeks, demonstrating filled lesion with new tissue

This is another example of diagnostic ultrasound assisting to plan the rehabilitation process. At 5 weeks I felt confident to prescribe more demanding rehabilitation exercises  as there was objective proof that the defect had healed more or less completely. It was also at this point that he no longer felt much discomfort which clinically supported the rehab program further.  However in my experience this is not always the case I have seen a few examples of healing lagging behind functional ability at which point high impact activity risks re injuring the site.

Please see attached free text article by Hayashi et al, (2012) which shows both MRI and US imaging in muscle injuries.

References:

Hayashi, D., Hamilton, B. & Guermazi, A (2012) Traumatic injuries of thigh and calf muscles in athletes: role
and clinical relevance of MR imaging and ultrasound, Insights Imaging, 3, 591-601.

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