Yoshida Kazuhiro, Fukushima Kensuke, Sakai Rina, Uchiyama Katsufumi, Takahira Naonobu, Ujihira Masanobu
Department of Medical Engineering and Technology, Kitasato University, Sagamihara, Kanagawa, Japan.
Department of Orthopaedic Surgery, Kitasato University, Sagamihara, Kanagawa, Japan.
Proc Inst Mech Eng H. 2021 Jan;235(1):65-72. doi: 10.1177/0954411920960000. Epub 2020 Sep 30.
Excellent primary stability of uncemented acetabular shells is essential to obtain successful clinical outcomes. However, in the case of developmental dysplasia of the hip (DDH), aseptic loosening may be induced by instability due to a decrease of the contact area between the acetabular shell and host bone. The aim of this study was to assess the primary stability of two commercially-available acetabular shells, hemispherical and hemielliptical, in normal and DDH models. Synthetic bone was reamed using appropriate surgical reamers for each reaming condition (normal acetabular model). The normal acetabular model was also cut diagonally at 40° to create a dysplasia model. Stability of the acetabular components was evaluated by the lever-out test. In the normal acetabular model conditions, the maximum primary stabilities of hemispherical and hemielliptical shells were observed in the 1-mm under- and 1-mm over-reamed conditions, respectively, and the resulting stabilities were comparable. The lateral defect in the dysplasia model had an adverse effect on the primary stabilities of the two designs. The lever-out moment of the hemielliptical acetabular shell was 1.4 times greater than that of the hemispherical acetabular shell in the dysplasia model. The hemispherical shell is useful for the normal acetabular condition, and the hemielliptical shell for the severe dysplasia condition, in the context of primary stability.
非骨水泥髋臼杯的良好初始稳定性对于获得成功的临床结果至关重要。然而，在发育性髋关节发育不良（DDH）的情况下，髋臼杯与宿主骨之间的接触面积减小导致的不稳定可能会引发无菌性松动。本研究的目的是评估两种市售髋臼杯，即半球形和半椭圆形髋臼杯，在正常模型和DDH模型中的初始稳定性。针对每种扩孔条件（正常髋臼模型），使用合适的手术扩孔器对合成骨进行扩孔。正常髋臼模型也以40°角斜切以创建发育不良模型。通过撬出试验评估髋臼组件的稳定性。在正常髋臼模型条件下，半球形和半椭圆形髋臼杯的最大初始稳定性分别在扩孔小于1毫米和大于1毫米的条件下观察到，并且所得到的稳定性相当。发育不良模型中的外侧缺损对两种设计的初始稳定性有不利影响。在发育不良模型中，半椭圆形髋臼杯的撬出力矩比半球形髋臼杯大1.4倍。就初始稳定性而言，半球形髋臼杯适用于正常髋臼情况，而半椭圆形髋臼杯适用于严重发育不良情况。
