Collateral Ligament Lateral Knee

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. 

The lateral aspect of the knee joint is examined by asking the patient to rotate the leg internally. From anterior to posterior, the structures to be evaluated are the distal aspect of the iliotibial band, the external femorotibial joint space with the lateral meniscus, the lateral collateral ligament, the popliteus tendon and the superior tibiofibular joint. 

Just deep to the proximal part of the lateral collateral ligament, the popliteus tendon can be imaged on coronal US planes as an oval structure located in its bony groove (Fig. 14.34). Depending on the incidence of the US beam, substantial anisotropy may be evident in the popliteus tendon (De Maeseneer et al. 2002). The US examination of the lateral aspect of the knee should be completed with an evaluation of the superior tibiofibular joint. Transverse and coronal US scans obtained over the anterior aspect of the fibular head are adequate for this purpose. 

Lateral knee pain is a common clinical challenge that may be secondary to a variety of soft-tissue and intra-articular disorders. US is able to provide clinically useful information to identify injuries of the lateral collateral ligament and the iliotibial band as well as meniscal cysts. In addition, it can give a full depiction of ganglion cysts arising from the... 

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