A 49-year-old physician suffers a right ankle injury, following an inside-the-park home run to help his team win a crucial baseball game. After crossing the plate, the man leaps up onto the back supporting fence to slow his speed but in the process catches a cleat on the fence, wrenching his right heel down and forward while fixing his forefoot. An MRI the next day revealed the abnormality (Fig. 1 right).
What’s the most likely diagnosis regarding this man’s ankle injury?
a) anterior tibial dislocation on the talus
b) calcaneal mid-body fracture
c) lower tibial shaft fracture
d) subtalar joint disruption with marked bone marrow edema of talus and calcaneus
e) torn and displaced Achilles’ tendon
e) torn and displaced Achilles’ tendon
Figure 1 reveals a displaced complete tear of the Achilles’ tendon, approximately 4-5 cm from its insertion point upon the posterior calcaneus. Refer to Figure 2, which is an MRI of an intact Achilles’ tendon for comparison. The opposing ends of the torn Achilles’ are displaced by 3-4 cm, with a moderate amount of bright fluid signal interposed, in keeping with post-traumatic hemorrhage.
The tibiotalar alignment is normal, ruling out anterior tibial dislocation on the talus. The calcaneal mid-body is also well seen with no fracture present. The marrow signal of the lower shaft of the tibia is normal with no fracture or cortical disruption. As well, the subtalar joints are normal as seen on this one view with no appreciable bone marrow edema in the talus or calcaneus.
The Achilles’ tendon is the longest and thickest tendon in the human body, formed by the confluence of the 2 bellies of the gastrocnemius muscle and the soleus muscle. On T2-w and PD MR images of the ankle, the Achilles’ tendon typically appears as a uniformly hypointense (black) vertical linear structure, which inserts along the postero-superior aspect of the calcaneus. On axial images, the tendon appears as a low-signal ovoid structure with a convex posterior surface and a flat or concave anterior surface.
Achilles’ tendon tears may be categorized as insertional or non-insertional, as well as partial or complete. Most partial and complete tears occur at a point 2-6 cm proximal to the insertion upon the calcaneus. Most complete ruptures occur in younger patients, as compared to other tendon ruptures (often seen in the elderly populations), with a mean of 35 years. However, it’s a rare occurrence prior to adolescence. The majority of patients are male and the etiology is typically sports-related, so as such, the peak incidence is in the summer months in Canada. The specific activity to cause the rupture varies around the globe, according to the popularity of various sporting events. In North America, the leading sports involved include jogging, squash, baseball and tennis. In Europe, soccer leads the charge.
There’s a myriad of conflicting articles in the medical literature as to the best routes for treatment of partial and complete thickness tears — from a variety of non-surgical routes (including injecting varying forms of collagen-like substances in the tendon gap to promote bonding of the tattered ends) to full open surgery with re-attachment of the displaced tendon ends (the route taken in the above case).
The imaging modalities of choice to assess Achilles’ tendon pathology are MRI and ultrasound (US). The MRI provides superior spatial resolution with a wider field of view to assess relationships with surrounding bony and soft tissue structures. However, US is often much easier to obtain, cheaper to perform and much quicker (10-15 minutes vs up to 45 or more minutes for an MRI, depending on planes and sequences utilized).
Personal side note: The image presented on the title page of this month’s Analyze This! is of particular interest to the author, as it is of his own right Achilles’ tendon! The initial tear occurred in early July 2010, requiring surgical reconstruction. This was followed by a fluke re-tear of the same Achilles’ in late August 2010 (despite being extra cautious in a futile attempt to avoid any possibility of such a re-tear), with a second surgery to follow. The non-resorbable stitch utilized to secure the displaced ends of the Achilles’ tendon in the 2nd surgery ended up becoming a nidus of ongoing infection and inflammation since that second surgery, with 7 subsequent bouts of lengthy antibiotics required to keep the ankle quiescent. In early April 2011, a painful abscess developed necessitating a third and (hopefully) final surgery in mid-April, where the offending stitch was removed, the Achilles’ cavity that resulted was packed with gentamycin-impregnated collagen and the tendon was closed with resorbable sutures. The ankle (just days after surgery as this article is being written) already feels 100% better. As such, I thought it was finally time to utilize the image in a Parkhurst Analyze This! article. Enjoy!
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