A 64-year-old man comes to the emergency department with left ankle pain. The patient was playing tennis 2 days ago, attempted to pivot, and felt a sharp pain in his ankle. He has since had difficulty walking and stumbled on the stairs yesterday. On examination, the patient can bear weight, but it is painful. There is diffuse swelling of the ankle. Pulses and sensation in the left foot are normal. Passive range of motion is normal in all directions. Active plantar flexion and dorsiflexion are present. With the patient in the prone position, squeezing the left calf does not cause movement in the left foot. Left ankle x-ray shows soft tissue swelling but no fracture. Which of the following will be most impaired on physical examination?

Question

A 64-year-old man comes to the emergency department with left ankle pain.  The patient was playing tennis 2 days ago, attempted to pivot, and felt a sharp pain in his ankle.  He has since had difficulty walking and stumbled on the stairs yesterday.  On examination, the patient can bear weight, but it is painful.  There is diffuse swelling of the ankle.  Pulses and sensation in the left foot are normal.  Passive range of motion is normal in all directions.  Active plantar flexion and dorsiflexion are present.  With the patient in the prone position, squeezing the left calf does not cause movement in the left foot.  Left ankle x-ray shows soft tissue swelling but no fracture.  Which of the following will be most impaired on physical examination?

Quizplus · Accepted Answer

This patient who had a sudden, sharp pain in his left ankle while pivoting now has no left foot movement (ie, passive plantarflexion) when the examiner squeezes the calf (ie, simulates gastrocnemius muscle contraction). This presentation is most consistent with Achilles tendon rupture. The Achilles tendon connects the gastrocnemius and soleus muscles to the calcaneus and plantar flexes the foot. The diagnosis of acute Achilles tendon rupture may be easily missed because edema or hematoma can mask a palpable tendon defect. The most reliable physical examination maneuver for checking for complete Achilles tendon rupture is the calf squeeze test (ie, Thompson test). With the patient prone and the feet hanging off the table, the clinician squeezes the calf, shortening the gastrocnemius muscle. If the foot passively plantar flexes in response, the Achilles tendon is at least partially intact; the absence of passive plantar flexion indicates complete tendon rupture. Achilles tendon Thompson test Despite Achilles tendon rupture, active plantar flexion can still be present (as in this patient) because of the action of accessory muscles of plantar flexion (eg, plantaris, flexors hallucis longus and digitorum longus) that insert directly onto the foot, rather than the Achilles tendon. These accessory muscles can even maintain some ambulation, although it is typically more difficult. In general, complete tendon rupture results in an impaired ability to walk on the tips of the toes because this movement requires the power of the gastrocnemius and soleus muscles (ie, accessory muscles of plantar flexion are insufficient). (Choices A and B) Foot eversion is controlled primarily by the peroneus muscles, which insert mainly onto the lateral aspect of the foot. Foot inversion is controlled by the tibialis anterior and posterior muscles, which insert primarily at the medial aspect of the foot. Neither foot eversion nor inversion would be significantly impaired in this patient because none of these muscles attaches to the ruptured (Achilles) tendon. (Choice C) Walking heel to toe (ie, tandem gait test) is typically used to evaluate balance and gait and can help identify vestibular or cerebellar dysfunction. An Achilles tendon rupture should not significantly impair balance. (Choice D) Heel walking is a sensitive test used to evaluate for impaired dorsiflexion (eg, footdrop). Plantar flexion, rather than dorsiflexion, is impaired in Achilles tendon rupture. Educational objective: The diagnosis of acute Achilles tendon rupture can be easily missed and is best evaluated on physical examination with the calf squeeze test, which simulates gastrocnemius contraction. Absent foot plantar flexion in response to calf squeeze is consistent with Achilles tendon rupture. References: Achilles tendon injuries. (http://www.ncbi.nlm.nih.gov/pubmed/28194638)

A 64-Year-Old Man Comes to the Emergency Department with Left