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.
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 despite physical therapy, which makes appropriate attention to acute ankle sprains important.
Table 41–8.Injuries associated with ankle sprains. |Favorite Table|Download (.pdf) Table 41–8. Injuries associated with ankle sprains.
Subtalar joint sprain
Sinus tarsi syndrome (ongoing anterolateral post-traumatic ankle pain)
Syndesmotic (distal tibiofibular ligamentous) sprain
Lisfranc (tarsometatarsal bony or ligamentous) injury
Posterior tibial tendon strain
Peroneal tendon subluxation
Osteochondral talus injury
Lateral talar process fracture
Posterior impingement (os trigonum)
Fracture at the base of the fifth metatarsal
Jones fracture (between base and middle of fifth metatarsal)
Salter (growth plate) fracture (fibula)
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 ATF ligament.
eTable 41–4.Ankle examination.