The anterolateral ligament of the knee is not a solid structure in human fetuses.

Purpose The purpose of this study was to investigate if the anterolateral ligament of the knee (ALL) is present in the human fetus and describe its topography along with other structures of the region. Methods Forty human fetuses knee joints, at mean age 34 weeks (± 2.57 weeks), fixed in 10% formalin, were submitted to cross-sectional dissection and mesoscopic analysis. Results The ALL was not identified, although the usual topography of the region was identified in all specimens: skin, subcutaneous tissue, iliotibial tract (ITT), fibular collateral ligament, popliteal muscle tendon, lateral meniscus, patellar ligament, infrapatellar fat pad, lateral patellar retinaculum, knee joint capsule, lateral inferior genicular vessels, and the biceps femoris tendon. The ITT reveals anterior (n = 12) and lateral thickening (n = 17) in some specimens. This thickening was found in both knees of the same subject in 6/20 specimens. Conclusion The anterolateral ligament of the knee is not a congenital or solid structure. Our results suggest that the ALL may be a deep layer of the ITT or part of the knee joint capsule, or its identification is evaluator dependent.