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1. INVERSION ANKLE SPRAINS

ESSENTIALS OF DIAGNOSIS

  • Localized pain and swelling.

  • The majority of ankle injuries involve inversion injuries affecting the lateral ligaments.

  • Consider chronic ankle instability or associated injuries if pain persists for longer than 3 months following an ankle sprain.

General Considerations

Ankle sprains are the most common sports injuries seen in outpatient clinics. Patients usually report “turning the ankle” during a fall or after landing on an irregular surface such as a hole or an opponent’s foot. The most common mechanism of injury is an inversion and plantar flexion sprain, which injures the anterior talofibular (ATF) ligament rather than the calcaneofibular (CF) ligament. Other injuries that can occur with inversion ankle injuries are listed in Table 41–8. Women appear to sustain an inversion injury more frequently than men. Chronic ankle instability is defined as persistent complaints of pain, swelling, and giving way in combination with recurrent sprains for at least 12 months after the initial ankle sprain. Chronic ankle instability can occur in up to 43% of ankle sprains even with physical therapy, which makes appropriate attention to acute ankle sprains important.

Table 41–8.Injuries associated with ankle sprains.

Clinical Findings

A. Symptoms and Signs

The usual symptoms following a sprain include localized pain and swelling over the lateral aspect of the ankle, difficulty weight bearing, and limping. The patient’s ankle may feel unstable. On examination, there may be swelling or bruising over the lateral aspect of the ankle. The anterior, inferior aspect below the lateral malleolus is most often the point of maximal tenderness consistent with ATF and CF ligament injuries. The swelling may limit motion of the ankle.

Special stress tests for the ankle include the anterior drawer test (eTable 41–4); the clinician keeps the foot and ankle in the neutral position with the patient sitting, then uses one hand to fix the tibia and the other to hold the patient’s heel and draw the ankle forward. Normally, there may be approximately 3 mm of translation until an endpoint is felt. A positive test includes increased translation of one foot compared to the other with loss of the endpoint of the anterior talofibular ligament.

eTable 41–4.Ankle examination.

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