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PATHOLOGY

 

Sprains are injuries involving ligaments, which are fibrous connective tissue that attaches bones to bones. Ligaments are found in joints to provide stabilization and motion of the joints articulating surfaces (Prentice 2011). The anterior talofibular (ATF) ligament is associated with injuries of the foot in an inverted, plantar flexed and internally rotated motion. Since the design of the ankle joint naturally allows for these three motions to occur the most, lateral ankle sprains involving the ATF are very prominent. Injury to the calcaneofibular ligament is associated with a more excessive inversion movement, and the posterior talofibular ligament is more commonly injured with severe sprains that cause a posterior dislocation of the talus (Prentice, 2011).

 

Ligament sprains and muscle strains are often given a number on a grading scale to identify the amount of damage was caused to the structure. Most clinical grading scales include a number from one, least severe, to three, most severe. For a lateral ankle sprain, the grading scale accounts for damage caused to all three ligaments in the lateral ankle  (Lynch 2009).

 

 

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GRADING SCALE

 

  • Grade I: Mild. Grade I strains usually involve only an excessive stretch of the ATF ligament. Microscopic damage is present, but damage on a larger scale is not prominent. Mild swelling and point tenderness around the ATF are seen with these strains, along with minimal loss of function.

  • Grade II: Moderate. Grade II strains are more significant than grade I, and involve damage to the ATF with additional mild damage to the calcaneofibular ligament. The damage to the ATF is usually a partial tear while damage to the calcaneofibular ligament is at most an excessive stretch. Moderate point tenderness, swelling, some functional loss and instability are usually seen with a Grade II sprain.

  • Grade III: Severe. Grade III strains involve the complete rupture of the ATF, with a partial or complete tear of the calcaneofibular ligment, and moderate damage to the posterior talofibular ligament. Swelling, pain, point tenderness, loss of function, and joint instability are very prominent in a grade III sprain. Surgical intervention is often the treatment for a sprain as severe as this.

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MECHANISM OF INJURY

 

Twisting of the ankle in inversion, inversion/plantar flexion, or inversion/plantar flexion/internal rotation in conjunction with a falling or direct trauma to the ankle. Running across uneven ground, quick change in directions or improper landing from a jump can all cause the ankle to twist in the wrong direction. Improper healing from previous ankle injuries, decrease in strength in the muscles of the ankle and joint instability, stiffness or degeneration can increase a person’s risk for a lateral ankle sprain.

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SIGNS AND SYMPTOMS

 

  • Swelling in sinus tarsi, around lateral malleolus, behind Achilles tendon.

  • Ecchymosis around lateral malleolus, along 5th metatarsal, over lateral aspect of ankle

  • Point tenderness over sinus tarsi, around and over lateral malleolus, lateral aspect of ankle

  • A “popping” sound or the feeling of a pop during the injury

  • Loss of range of motion in ankle

  • Instability in ankle

  • Inability to weight bear on ankle

  • Heat around area due to inflammation

DIFFERENTIAL DIAGNOSIS

 

  • Jones Fracture: Fracture of the base of the 5th metatarsal.

  • Fracture to a Tarsal bone

  • Distal Fibular Fracture

  • Syndesmotic sprain (high ankle sprain): Sprain to the Anterior/Posterior Tibiofibular ligaments

  • Peroneal tendon strain or rupture

  • Flexor tendon strain or rupture

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