How To Diagnose Lateral Ankle Injuries

By Remy Ardizzone, DPM, and Ronald L. Valmassy, DPM

   Without physical therapy, the ligaments will heal in a “stretched out” or loosened position that contributes to instability. Employing U-shaped padding about the lateral malleolus in combination with compression promptly after the injury can minimize the swelling. It is the persistent swelling about the ligaments that helps maintain the stretched out position. Using an ankle stabilizer brace will help support the ligaments while allowing normal ankle function and alignment. Physical therapy not only helps patients regain full strength but also facilitates proprioception, which is essential in preventing instability.

   While the ankle sprain is a common injury, chronic lateral ankle instability typically requires a history of recurrent inversion sprains. Patients will often complain that the affected ankle feels “unstable” or “gives out” frequently. They typically feel unsteady when walking on uneven ground or sloped surfaces. Repeat inversion injuries will occur with the slightest provocation. Not uncommonly, these patients report twisting or spraining their ankles every few months with varying levels of severity.7,12 Bracing or taping may not provide adequate stability.

   Clinically, physical examination findings commonly reveal persistent swelling to the anterolateral aspect of the ankle, even if there has been no recent re-injury. There may or may not be tenderness to palpation of the anterior talofibular ligament or calcaneofibular ligament. Typically, one will see a positive anterior drawer sign or anterior displacement of the talus from the tibia, similar to what clinicians would see with an acute ankle injury. There is also increased inversion of the talus in the ankle mortise, particularly when one compares this to the contralateral ankle. When there is attempted rotary motion of the ankle within the mortise, the talus will often translocate laterally.

How To Perform And Assess Talar Tilt And Anterior Drawer Tests

   Specific diagnostic tests are required to definitely diagnose instability. Most practitioners perform manual stress X-rays of the ankle. Like most manual tests, accuracy and reproducibility depend on the skill of the practitioner. One can reduce this variability by using a stress device machine, which exerts a constant pressure of 15 kPa in an attempt to displace the talus within the ankle mortise. However, access to such equipment is limited. In either case, the specific diagnostic tests consist of talar inversion stress (talar tilt) and anterior displacement stress (anterior drawer). In most cases, one should apply both tests to the symptomatic as well as the asymptomatic ankle.

   Originally described by Farber in 1932, the talar tilt test refers to the angle formed during forceful inversion of the hindfoot between the talar dome and tibial plafond. One may perform this test by cupping the patient’s calcaneus in one’s hand, keeping the thumb clear of the ankle joint, and stabilizing the tibia with the other hand. Then the clinician would invert the calcaneus and talus as far as possible given the patient’s tolerance. The practitioner holds this position while an AP X-ray is taken. If the patient resists movement in any way, then it may be necessary to administer a local anesthetic block to the ankle. Typically, this is not necessary with manual exams but is often required when using a stress device machine. Exact measurements vary but generally the test is considered positive when the angle of talar tilt measures greater than 18 degrees or differs from the contralateral side by more than 5 degrees.7,13

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