Figure 1. Magnetic resonance imaging of the right ankle.
A 33-year-old man presents with pain and weakness in his right ankle after an injury sustained 1 week ago, when he felt a pop in his heel while running up a hill. He has had tendinitis in the Achilles tendon of the same ankle for a few months. Physical examination reveals tenderness over the Achilles proximally and a positive Thompson test. Magnetic resonance imaging (MRI) shows an acute tear of the Achilles tendon at the musculotendinous junction (Figure 1).
Submit your diagnosis to see full explanation.
Rupture of the Achilles tendon can result from sudden, forceful plantar flexion of the ankle, much like a sprinter starting a race. In the United States, half of all ruptures of the Achilles tendon occur while playing basketball and racket sports.1 The majority of ruptures occur in the avascular mid-tendon 3 to 4 cm proximal to the calcaneal insertion. An Achilles tendon can also tear at the musculotendinous junction or proximal to where the muscle fibers of the soleus attach to the tendon, although this is not as common. A palpable defect or pain to palpation generally locates the area of the suspected tear. Pain to palpation proximal to the mid-tendon may indicate a myotendinous tear, in which case MRI should be ordered for confirmation. Unlike tears of the mid-tendon that can be repaired with suture, myotendinous tears are not amenable to this. Surgical repair of mid-tendon tears is successful as the tissue is strong enough to support end-to-end suture. Muscle does not hold suture and is not repaired to tendon using this technique. Because muscle heals well to tendon on its own, myotendinous tears do not require surgical correction. Patients with myotendinous tears are often placed in a walking boot with a heel wedge to position the ankle in slight plantar flexion. The heel wedge is removed in 3 to 4 weeks and the boot in 6 to 8 weeks.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
1. Uquillas CA, Guss MS, Ryan DJ, Jazrawi LM1, Strauss EJ. Everything Achilles: knowledge update and current concepts in management. J Bone Joint Surg Am. 2015;97:1187-1195.
2. Ahmad J, Repka M, Raikin SM. Treatment of myotendinous Achilles ruptures. FootAnkle Int. 2013;34(8):1074-1078.