Sonographic imaging of the posterolateral structures of the knee: findings in human cadavers.

PURPOSE: To evaluate and characterize the use of sonography in imaging the posterolateral structures of the knee in human cadavers. TYPE OF STUDY: In vitro laboratory investigation using human cadavers and sonography.
METHODS: Three cadaver knees were dissected to expose the posterolateral corner with the skin and subcutaneous tissue removed. The iliotibial band, biceps femoris muscle and tendon, lateral gastrocnemius tendon, the lateral collateral ligament, the popliteus tendon, the popliteofibular ligament, the arcuate ligament, and the fabellofibular ligament (when present) were identified. Following the soft tissue dissection, sonography was performed to characterize these structures. The technique was refined using this "open" examination method as anatomical and structural detail was noted. After adequate familiarization with this technique, researchers performed sonography on 2 pairs of thawed fresh-frozen cadaver knees, 1 pair with a fabella and 1 pair without a fabella. After sonographic examination of all of the posterolateral structures, the knees were dissected and the structures previously identified by sonography were verified.
RESULTS: In all 4 cadaver specimens, all posterolateral structures were identified based on their imaging characteristics and surrounding bony and soft tissue landmarks. We also present dissection photographs and sonographic images depicting our study findings.
CONCLUSIONS: Sonographic imaging may provide the clinician with valuable information regarding the posterolateral structures of the knee. To our knowledge, this is the first study to investigate the sonographic findings of these structures. This technique may assist the physician evaluating these injuries and help in preoperative planning for repair or reconstructive procedures. Further research is needed to determine the accuracy of sonography in identifying injured posterolateral corner knee structures in vivo.