Collateral Ligament Lateral Ankle

Fractures of the head and neck of the fibula occur rarely in isolation and are more commonly associated with proximal tibial fractures, especially compression, bicondylar and subcondylar fractures. A spiral fracture of the proximal fibula is often associated with an ankle fracture, resulting from an external rotation force. These fractures are known as Maisonneuve fractures. Fibula head fractures can occur from direct impact, valgus stress (associated with a tibial condylar fracture), and varus injuries. Varus stresses can cause avulsion of the fibular styloid at the site of the biceps tendon and fibular (lateral) collateral ligament. Peroneal nerve injury is not uncommon with these injuries. Dislocation of the proximal fibula is often missed on the initial radiograph. 

This test evaluates the medial and lateral collateral structures. With the patient supine, the ankle joint is held between the examiner s side and arm, thus freeing both hands. The knee is tested in full extension by applying a valgus and then a varus force to the proximal tibia (abduction-adduction motion of leg) (Fig. 94-1). The examiner notes any instability or increased motion on application of force in either direction. Then the test is repeated with the knee slightly flexed. If the cruciate ligaments are intact, motion can be stable with the knee in full extension, even with collateral ligament rupture. 

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