Acute care for ankle sprain

The history: In ankle injury, the history can be an opportunity to prepare the patient for the painful phases of the exam. In addition to applying ice, elevating the leg, and trying to gain the patient’s confidence, consider giving an agalgesic. The mechanism of the injury can help in diagnosis, while degrees of pain and swelling are less specific indicators. In children with open epiphyses keep a high index of suspicion for fracture of the growth plate.

In assessing the severity of an ankle injury, the history taking offers not only useful information but also an opportunity to gain the patient’s confidence, which can help when you come to the painful phases of the examination. Keeping the ankle elevated with ice packs applied during the history also helps, as does examining the uninjured ankle first when you do begin the exam. For some patients in severe pain, giving an analgesic before beginning the physical examination may be important in making the exam tolerable. You could try meperidine HCl (Demerol) or acetaminophen with codeine (Anacin-3 w/Codeine, Empracet w/Codeine, Tylenol w/Codeine, etc.).

Knowing the mechanism of injury can be helpful in diagnosis. An injury sustained while playing basketball, volleyball, gymnastics, or another sport that involves jumping is likely to be a typical lateral inversion sprain, while fracture is more likely if the injury occurred in a high-energy activity such as motorcycling. A patient’s report that the injury was accompanied by a crack or snap may indicate fracture or tendon injury.

In children with open epiphyses, fracture to the growth plate is always a possibility. While more severe epiphyseal fractures are relatively easy to recognize and can be picked up on X-ray, a Salter-Harris type I fracture is not obvious and may not show any displacement on X-ray. If a child has ankle pain, the mechanism of injury seems severe enough to have caused ligamentous damage, and there is local swelling, assume fracture. As a rule, the ligaments are stronger than the epiphyses in children: Sprains around the epiphyses are rare, and in fact Salter-Harris type I fractures may be more common.

The patient who sustains an ankle injury while running may have more than just a sprain. Runners are prone to stress fractures. Ask the runner if he or she has recently changed to a new type of running shoe, started running on a different surface, or increased mileage.

A history of repeated sprains suggests the possibility of chronic ankle instability. The patient with such instability could benefit from referral to an orthopedist for evaluation. Orthotic treatment frequently obviates surgery.

The degrees of pain and swelling are relatively unspecific gauges of the severity of an injury. Hairline fractures may not produce any swelling, for instance, although they usually do produce some pain. The degree of swelling also depends in part on whether the patient applied ice packs before coming in–and on a variety of factors such as whether the patient waited to come in because he did not want to “bother the doctor.’

EXPRESS STOP

Physical examination: Examining the injured ankle allows you to assess stability and identify areas of suspicion for X-ray. Examine both lower extremities from hips to toes. Identify areas of pain. The pain of fracture is often well localized. Carry out the anterior drawer test if it can be done without intolerable pain. Test the uninjured ankle first for comparison. A negative test does not rule out instability if the patient resists the force applied by the examiner.

The major objectives of the physical examination in ankle injury are to assess the stability of the ankle and to identify areas of suspicion for radiologic examination. Since the patient’s injuries may not be limited to the ankle, assess the alignment of both lower extremities from hips to toes. If possible, observe how the patient stands and walks.

While the patient is supine, compare the appearance, positions, and attitudes of the extremities. The presence of ecchymoses and swelling suggests high-energy trauma involving torn, bleeding ligaments or, perhaps, fracture or injury of the tibia or fibula. A noticeable inversion of the injured foot as compared with the other one is indicative of severe sprain or fracture.

Have the patient point to where pain is localized. Identify areas that are painful on palpation. Pain during isometric muscle contractions suggests a muscle or tendon injury. Fractures and dislocations generally produce pain well localized to the area of the injury.

Fractures of the malleoli are serious injuries that require immediate orthopedic referral, as do all displaced and compound fractures. Swelling with a palpable deficiency of tissue over the lateral malleolus and inversion of the foot suggests that the lateral ligament has been avulsed from the malleolus.

If you find that the injury does not require immediate orthopedic attention (see “Ankle injury: Indications for consultation’), you might consider splinting the ankle and sending the patient home for 48-72 hours with instructions to apply ice packs, keep the ankle elevated, and return for examination when the swelling has gone down and the pain has abated.

The anterior drawer test is useful for assessing the stability of the anterior talofibular ligament if it can be carried out without causing intolerable pain. With the patient supine, place the palm of one hand on the distal tibia and the other on the heel. Pull slowly and steadily forward on the heel with about 20 lb of force while stabilizing the tibia (see Figure 1). Do the test on the uninjured ankle first to obtain a basis for comparison. Some individuals have normally lax ligaments.

If the visible or palpable laxity is more than 3 mm (1/8 in) greater in the injured ankle than in the uninjured one, the patient probably has a grade II or III sprain of the anterior talofibular ligament (see “The three grades of ankle sprain,’ page 54). You might also feel a subtle grinding or a vibration, which is another indication of instability.

Failure to elicit a visible or palpable clinical sign with the anterior drawer test does not rule out injury if the patient resists the examiner. X-rays taken during a repetition of the test and during the inversion test (see “X-ray examination’) may still demonstrate instability.

EXPRESS STOP

X-ray examination: Ankle injures involving pain and swelling practically demand X-ray studies. If AP, lateral, oblique, and mortise views of both ankles rule out fracture, consider stress testing–under local anesthesia, if necessary. In the anterior drawer test, look for anterior displacement of the talus. In the inversion test, measure the tilt of the talus on the tibia. In both cases use the unaffected leg as the normal reference.

Most authorities agree that X-rays are practically mandatory in any situation involving pain and swelling in the ankle region. While stress X-rays are important in evaluating sprains, it is important to obtain AP, lateral, oblique, and mortise views of both ankles first to rule out fractures (see Figure 3, page 57). Two types of stress X-rays are usually included in the ankle evaluation: the anterior drawer test and the inversion test. You might want to consider performing the radiographic stress testing yourself under some circumstances –if, for instance, the patient seems likely to be more relaxed and cooperative with his or her own physician.

If pain or the patient’s anxiety about manipulation of the injured ankle seems likely to interfere with the exam, a local anesthetic such as 0.5% lidocaine HCl (Xylocaine) might be necessary. If so, give it once the physical examination is complete and the preliminary X-rays are obtained. Under sterile technique, inject the lidocaine along the deltoid ligament and into the intra-articular talofibular joint.

To perform the stress testing, the examiner, protected by a lead apron and gloves, sits on a stool at the feet of the recumbent patient. The anterior drawer test is performed as during the physical exam, but with the patient positioned on his side with the lateral aspect of the lower foot on the X-ray plate, the other leg crossed over (see “Physical examination’ for testing technique). A positive X-ray will show a greater anterior displacement of the talus on the affected side, indicative of damage to the anterior talofibular ligament. This gap may not be obvious except by comparison with the same view of the uninjured ankle.

For the inversion test, the patient lies supine. Grasping the talus and calcaneus, the examiner applies an inverting force–one that tends to turn the sole of the foot inward (see Figure 2, page 51). In examining the film, look for a talar tilt in the mortise–that is, a tilt of the talus with respect to the tibia (see Figure 4, page 57). Since the normal tilt varies substantially, consider the tilt of the uninjured ankle the normal for the patient. If the injured ankle tilts at least 6 degrees more than the uninjured one, the calcaneofibular and anterior talofibular ligaments are both torn. (Usually, the calcaneofibular ligament will not tear until the anterior talofibular ligament does.)

EXPRESS STOP

Treatment: Immobilization of the injured ankle is the basic tactic of initial therapy. Grade I sprains can often be managed with elevation and ice, and few sprains need casting. Avoid casting severely swollen limbs. Athletes or others desiring quick return to mobility can be treated with taping and rehabilitative therapy. Splinting is recommended for most patients. Inflatable ankle braces have become popular alternatives to taping and casting.

While early mobilization is important to rapid recovery from ankle sprains, immobilization of the joint is basic to initial treatment of almost all such injuries. Grade I sprains can usually be managed with nothing more than elevation and application of ice packs for 3-4 days. Compression, by means of an elastic bandage (Ace Bandage) applied over padding, may also help. Persistence of pain, swelling, or both is an indication for reevaluation.

In most more severe sprains, immediate orthopedic referral is unnecessary. Injuries ranging in severity from grade II and grade III sprains to nondisplaced fractures can generally be managed with secondary referral. The decision whether to obtain a consultation before treating is often complicated by the difficulty of distinguishing between grade II and grade III sprains. Stress testing can provide useful information for making this decision. If the inversion test is negative, the injury is likely to be a grade I or grade II sprain that can be treated successfully without surgery. A positive talar tilt on stress testing suggests a grade III sprain.

When immediate referral is indicated, a simple device such as a brace, pillow splint, air splint, or cardboard box splint can be used to prevent additional tissue damage while the patient is being transported. Once the foot is immobilized, check to make sure it is in a neutral position to avoid strangulation of circulatory supply distally.

Splinting is usually the best way to immobilize the joint. As few as 6% of sprains require casting. If examination and initial plain X-rays suggest a grade II or grade III sprain or a nondisplaced fracture, consider delaying casting and applying a well-padded posterior splint instead. Circular casts are not recommended when the limb is severely swollen and likely to swell more. Send the patient home with instructions to keep the affected limb elevated above heart level and to apply ice packs. After two or three days, the swelling should have subsided, and he or she can then return for casting, if necessary.

Many different kinds of ready-made splints are available. Be sure to pad the splint well before wrapping with woven gauze (Kerlix), stretch gauze, or elastic bandage (see Figure 5, page 58, for a more elaborate technique).

The choice of treatment for ankle sprains depends to a large extent on the patient’s life-style. If athletics are important to the patient with a grade I or grade II sprain, or if a bulky dressing would be particularly inconvenient, consider nonrigid dressings such as taping to allow early return to motion. With such treatment, however, the patient must have the time and willingness to undertake the necessary physical therapy. The taping technique used for athletes protects the ankle from additional eversion or inversion stress while allowing some plantar flexion and dorsiflexion. It also permits some walking and partial weight bearing. Early motion and weight bearing can provide a number of benefits, including decreasing muscle atrophy, promoting proper organization of collagen fibers during ligament healing, maintaining proprioception, and promoting lymphatic drainage.

The patient whose sprain is severe enough to require casting will need to spend 2-3 weeks in a short leg-walking cast, using crutches to help maintain balance. Be sure to trim the lateral superior aspect of the cast so that the peroneal nerve is not covered, and make sure the foot is in a neutral position. Immobilization in an equinus position may delay return to full ambulation.

Instruct the patient to report any tingling or loss of sensation in the toes and any swelling or pain. Chronic instability could result from premature return to full weight bearing and mobility, so if examination shows that the ankle is still unstable after 2-3 weeks of immobilization, continue the immobilization, recasting if necessary.

As alternatives to strapping and casting, various types of ankle braces are available. One that has become quite popular in recent years features an inflatable brace that surrounds the joint (Air-Stirrup Ankle Brace). Braces provide more support than taping, while allowing some dorsiflexion and plantar flexion. The simplicity of removal and reapplication facilitates an early return to motion. The patient can be weaned gradually from the device as the stability of the ankle joint returns. A brace can be used similarly after removal of a plaster cast.

Table: INITIAL MANAGEMENT OF ANKLE SPRAIN

Photo: Anatomy of the ankle

Photo: FIGURE 1: The anterior drawer test evaluates the stability of the anterior talofibular ligament. To perform the test, stabilize the leg with one hand while pulling forward on the heel with the other. When anterior movement of the talus with respect to the mortise is 3 mm (1/8 in) greater in the injured ankle than in the uninjured one, a grade II or III sprain is probable.

Photo: FIGURE 2: The inversion test can detect gross lateral instability of the ankle caused by tears in the anterior talofibular and calcaneofibular ligaments. The test is performed with the patient supine and the ankle over the X-ray plate. Stabilizing the tibia with one hand, the examiner applies an inverting force to the talus and calcaneus. A tilt of the talus with respect to the tibia that is at least 6 degrees greater on the injured side than on the uninjured side indicates that both ligaments are torn

Photo: FIGURE 3: A nonstress X-ray view can reveal severe ankle sprain as well as rule out fracture. Here a lateral view of the left ankle shows anterior subluxation of the talus from the tibia. Note the opening of the posterior ankle joint.

Photo: FIGURE 4: A tibiotalar tilt (TTT) produced in the inversion test can be measured on the film. While the results are often significant only when the injured and uninjured ankles are compared, extreme tilts such as this one are strongly suggestive of injury.

Photo: FIGURE 5: An effective ankle splint can be made by applying layers of cotton sheeting around the ankle and lower leg, adding a layer of stretch gauze over the cotton (a), applying a layer of plaster or other splinting material over the gauze to make a posterior splint (b), and covering the splint with stretch gauze or an elastic bandage.

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