The undefined anatomical variations of the deltoid ligament bundles: A cadaveric study

Introduction: Recently, Cromeens proposed a new interpretation of the deltoid ligament (DL) using its attachment sites to define individual components. The aim of this cadaveric study was to evaluate the reproducibility of this new classification and investigate anatomical variations of the ligament to contribute to reaching an evidencebased consensus regarding its ligamentous constituent bands, their origins and insertions. Methods: The classification was applied to study only four components of the DL: the tibiocalcaneonavicular (TCN), the superficial posterior tibiotalar (sPTT), the deep anterior tibiotalar (dATT) and the deep posterior tibiotalar (dPTT) ligaments. Fifteen fresh frozen ankles were dissected and the deltoid ligament components defined by their attachment sites and measured on the three axes. Results: The TCN, sPTT and dPTT ligaments were identified in all of the specimens. The TCN was the widest and longest ligament with variable thickness. The sPTT ligament was the second thicker and longer. The dATT ligament, the smaller and thinner, was not identified in 3 specimens. The dPTT ligament was the second wider, which in 3 cadavers presented an accessory bundle, the deep intermedial tibiotalar ligament (dITT ligament). Conclusions: Cromeens’s attachment-based classification was proved to be simple, rational and reproducible in allowing the methodological description of the different bands of the DL. Our findings showed that the dITT ligament must be considered a secondary bundle of the dPTT ligament, which was not always identified in all specimens. Level of evidence: IV. Clinical relevance The anatomical data regarding the deltoid ligament bands and their variations described in this study should promote correct management of ankle sprains in cases of deltoid ligament injury or instability, often trivialized, addressing the proper treatment: conservative or operative.