By Jacob W. Ufberg, MD
Achilles (calcaneal) tendon rupture is a condition that predominantly affects middle-aged men who sporadically participate in recreational sports. The diagnosis is frequently obvious, but may present in a manner similar to the much more common ankle sprain.
Approximately 25% of Achilles tendon ruptures are missed on the initial presentation, leading to delays in therapy and increased morbidity.1,2 This pitfall can be avoided by a careful history and physical performed by the treating emergency physician (EP).
Epidemiology and Pathophysiology
The mean age of patients with Achilles tendon rupture is 35 years. Most ruptures occur in men (2:1) who intermittently participate in sports requiring sudden acceleration or jumping.3-5 Approximately two-thirds of patients will be asymptomatic prior to rupture of the Achilles tendon.6 Persons with gout, systemic lupus erythematosus, and rheumatoid arthritis have an increased incidence of Achilles tendon rupture. Older patients taking corticosteroids or fluoroquinolones also are at increased risk for rupture, and this risk is higher still among patients taking both medications concurrently.7,8
The majority of Achilles tendon ruptures occur in the portion of the tendon with the least blood supply, approximately 2 to 6 cm above the calcaneous.3,9 Less common sites of rupture include the musculotendonous junction and the insertion site of the tendon on the calcaneous.
History and Physical Examination
Patients presenting to the emergency department (ED) with Achilles tendon rupture classically complain of the sudden onset of pain at the back of the ankle or lower calf while attempting to jump or to accelerate rapidly. However, in some cases, the mechanism may be much more mundane, such as dancing or lifting weights. Many patients may hear a "snap" or "pop" when the tendon ruptures. Rarely, the rupture may be painless.
The pain associated with rupture may resolve quickly, which may contribute to the fact that patients often do not seek care immediately. Rather, many patients will present with difficulty walking and poor ability to plantar-flex the foot. One source of misdiagnosis of these injuries is the misconception that patients with Achilles tendon rupture should be completely unable to plantar-flex the foot. In fact, plantar flexion usually is preserved (with decreased strength) due to the intact peroneal, plantaris, and tibialis posterior muscles.
Physical examination of a recently ruptured Achilles tendon should reveal a palpable and/or visible defect, usually 2 to 6 cm above the insertion of the tendon on the calcaneous. However, as the amount of time from injury to presentation increases, the defect may be obscured by hematoma formation and edema. Several physical examination tests are extremely reliable for the detection of Achilles tendon rupture. At least one of these tests should be performed in any patient presenting with symptoms consistent with Achilles tendon rupture, and perhaps in any patient with an ankle injury to prevent missing this important diagnosis.
Thompson’s test is the most widely used physical diagnosis test for Achilles tendon rupture. The patient may be positioned prone with the feet hanging over the edge of the table, or the patient may kneel on a chair with the feet hanging over the edge of the chair. The physician then squeezes the calf just distal to the area of maximal calf girth. If there is no plantar flexion of the foot, then the tendon is ruptured.10
Copeland first described sphygmomanometer testing in 1990.11 To perform this test, the patient may be prone or seated on the end of the stretcher with the knee flexed to 90° and the foot plantar-flexed. With a sphygmomanometer around the calf and the cuff inflated to 100 mmHg, the physician dorsiflexes the foot. If the tendon is ruptured, the sphygmomanometer pressure will change only minimally, whereas the pressure will increase to approximately 140 mmHg if the tendon is intact. If the result is unclear, the unaffected leg can be tested as a control.
The needle test is performed by placing a 25-gauge needle into the proximal muscle belly of the calf in the midline. The foot is then put through passive range of motion. If the Achilles tendon is ruptured, the needle should not move with foot motion. However, if the tendon is intact, the needle should move with passive range of motion of the foot.12 This test is quite reliable for detecting Achilles tendon rupture, but is used infrequently due to the pain involved in the procedure and less complicated alternatives.
Resistive plantar-flexion testing examines the strength of plantar flexion. Although plantar flexion is preserved in many patients with Achilles tendon rupture, generally it is reduced severely in strength. Thus, greatly reduced power in plantar flexion against resistance will be evident when the ruptured tendon is compared with the intact tendon. Some physicians test this by the ability of the patient to rise up onto the ball of the foot. However, this test may be quite painful in patients with an acute rupture, and may be difficult to test in patients with other foot and ankle injuries.
Although the ED diagnosis of Achilles tendon rupture is generally clinical, few cases may present with equivocal signs, symptoms, and physical exam findings. In these cases, diagnostic imaging may prove helpful in making or ruling out the diagnosis.
Soft-tissue Lateral Films of the Ankle. Kager’s triangle is an apex-superior triangle bordered inferiorly by the calcaneous, anteriorly by the deep flexor tendonsposteriorly by the Achilles tendon, and filled with fatty tissue. This triangle was found to be at least partially opacified in 100% of ruptures in one study by Cetti and Andersen.13 Other, less sensitive signs of rupture include Arner’s sign and a decrease in Toygar’s angle.
Toygar’s angle is measured along the line of the posterior skin surface on the radiograph where the Achilles tendon courses posteriorly as it approaches its insertion site on the calcaneous. This angle is normally greater than 150° but may decrease below that threshold in the setting of Achilles tendon rupture. Cetti’s series revealed abnormal measurements of Toygar’s angle in 12% of cases.
On a soft-tissue lateral of the ankle, the most inferior aspect of the Achilles tendon curves slightly outward after leaving its insertion site on the calcaneous. If the tendon is traced superiorly, it then assumes a linear course toward the top of the film. If the tendon is ruptured, the tendon may display a pathologic anterior curvature (rather than a linear course) known as Arner’s sign. Arner’s sign was present in 48% of ruptures in Cetti’s study.
Other Imaging Modalities. Magnetic resonance imaging (MRI) has excellent soft-tissue discrimination for diagnosing Achilles tendon rupture. It is especially beneficial for diagnosing partial tendon ruptures and for patients with chronic complaints or equivocal physical examination findings. However, MRI is expensive, often unavailable immediately, and frequently unnecessary for making the diagnosis. Ultrasound also may be used to diagnose rupture, and may be of greatest utility in evaluating patients with chronic Achilles tendon pain. Ultrasound of the Achilles tendon, like all ultrasound, is user-dependent and is limited by its mediocre discrimination of soft-tissues.
In patients with Achilles tendon rupture, the primary role of the EP is to make the diagnosis. Patients diagnosed with an acute rupture should be referred urgently (within 2 days) to an orthopedic surgeon if one is not immediately available.5,14 The affected leg should be splinted in the gravity equinus position (non-forcibly plantar-flexed), and the patient should be instructed not to bear any weight on that leg. Patients should be given analgesics, crutches, and appropriate follow-up instructions. Definitive treatment may be accomplished surgically or non-surgically, a subject that has been the source of much debate in the orthopedic literature.
Surgical treatment has been shown to lower the incidence of recurrent rupture, improve force of plantar flexion, and decrease the amount of calf muscle atrophy.14,15 The disadvantages of operative treatment include surgical complications such as infection, nerve damage, excessive tendon shortening, and thromboembolic events. Athletic patients likely would obtain the most benefit from operative management due to lower re-rupture rates and increased calf muscle strength.
Non-surgical treatment is accomplished through adequate apposition of the ends of the ruptured Achilles tendon. Patients are managed in this way using cast immobilization of the injured extremity in the gravity equinus position, although some orthopedic surgeons favor full equinus positioning.5,14,16 The leg remains immobilized for 6-8 weeks, followed by the use of a heel-lift in the patient’s shoe.
The main advantages of non-surgical management are the elimination of surgical complications, decreased time lost from work, and lower initial costs. Disadvantages include higher re-rupture rates (8-39%),15 decreased muscle strength due to lengthening of the injured tendon, and thromboembolic complications.14,16v
Rupture of the Achilles tendon is a significant injury frequently seen, with a significant potential to be missed, in the ED. Delays in diagnosis due to missed injuries affect the patient’s treatment options, and may result in poorer functional outcomes. The diagnosis of Achilles tendon rupture can be made using the history and physical examination. Ancillary studies generally are unnecessary to make the diagnosis. EPs should use Thompson’s test (or another of the physical examination tests for Achilles tendon rupture) any time Achilles tendon rupture is a clinical possibility to avoid missing this important diagnosis.
Dr. Ufberg, Assistant Professor of Emergency Medicine, Residency Program Director, Department of Emergency Medicine, Temple University School of Medicine, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.
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