This case involved a patient in their 70s who sustained an acute lateral ankle injury when turning and pivoting on his right foot whilst at work. The pain was very severe and he therefore visited his local Accident and Emergency department. He subsequently had an x-ray taken of the ankle as it was feared that he had fractured his ankle or his lateral foot. This was reported as normal.
I felt that the combination of clinical and US findings indicated a full thickness Peroneus Longus tendon tear. I referred him to an Orthopaedic ankle specialist pending an MRI scan that I had also requested.The MRI confirmed my suspicions of a FTT of peroneus longus (Figure 4), the full report being :'There is a full thickness tear of the peroneus longus tendon immediately distal to the cuboid tunnel within the plantar aspect of the foot. I cannot confidently identify an avulsed bony fragment. The peroneus brevis tendon is normal and intact. The anterior and medial tendons are normal and intact'.
The tear however was located more plantar than I had expected. In retrospect I think that the tendon appeared hypo-echogenic in Figure 2, simply due to the fact that it had lost its normal tension.
A useful reference point for a Peroneus Longus tendon rupture is this free access article by Smania et al (2007).
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