High-Resolution X-Ray Computed Tomographic Scanning of the Human Stapes Footplate

Abstract

Objectives: The mechanical behaviour of the footplate and its annular ligament depends critically on their shape and orientation in the oval window, but accurate measurements have been difficult to make owing to their small size. Our aims are to visualize the footplate at high resolution and understand its dynamics. Methods: The human cadaver stapes footplate was dissected, and very high-resolution x-ray computed tomographic (CT) scans, with voxel sizes from 4 to 8 µm, were performed. Locally developed software was used to reconstruct the images. Results: The data permit us to explore minor details of shape and orientation. The footplate looks like a footprint, and the annular ligament has variable thickness, with a cleft (groove) in its anterior attachment to the oval window. The CT data also permit us to create a three-dimensional finite-element model that can simulate footplate motion. Conclusions: The results obtained lead to further understanding of the mechanical behaviour of the footplate and the annular ligament. Sommaire Objectif: Le comportement mécanique de la platine et de son ligament annulaire dépend de leur forme et de leur orientation dans la fenêtre ovale, mais à cause de leur petite taille, leur mesure précise est difficile à évaluer. Nos objectifs étaient donc d'examiner la platine à forte résolution et d'en comprendre la dynamique. Méthode: Nous avons évalué des platines humaines cadavériques par TDM à très haute résolution (6 µm). Les images ont été reconstruites par un logiciel développé localement. Résultats: Les données nous permettent d'explorer des détails mineurs dans la forme et l'orientation de la platine, qui ressemble à une empreinte. Nous avons aussi noté que le ligament annulaire est d'épaisseur variable avec une fente dans son attache antérieure à la fenêtre ovale. Conclusion: Les résultats obtenus apportent une meilleure compréhension du comportement mécanique de la platine et du ligament annulaire.

Elastic Properties of the Annular Ligament of the Human Stapes—AFM Measurement

“…Moreover, the AL thickness near point 1 is almost twice as large as the thickness near point 2. This is consistent with the literature (Hagr et al 2004;Ohashi et al 2006;Sim et al 2013). Such an anatomical structure leads to a higher AL stiffness at the SF posterior edge (point 1) than at the anterior edge (point 2).…”

“…The shapes of both the OW niche and the SF are very irregular and vary among individuals (e.g., Hagr et al 2004;Sim et al 2013). Numerous authors have treated the AL as an elliptical ring in finite element modeling of the middle ear (Ladak and Funnell 1996;Sun et al 2002, Gan et al 2011, Gentil et al 2011.…”

Realistic 3D Computer Model of the Gerbil Middle Ear, Featuring Accurate Morphology of Bone and Soft Tissue Structures

“…In previous CT-based studies of the ME, the following model resolutions were reported: 5.5 μm on gerbil (Elkhouri et al 2006), 6 μm on human (Hagr et al 2004), 10 μm on cat (Decraemer et al 2003), and 10 μm on human (Vogel 1999). Though these numbers are comparable to our isometric 8.5-μm voxel size for μCT on gerbil bone, our data and models are of much higher quality than those shown in previous work.…”

Dynamic property changes in stapedial annular ligament associated with acute otitis media in the chinchilla

“…2C depicts the oval window length L3 and width L4. Previous histology on the human middle ear suggests that the SAL is thicker in the anterior than in the posterior [17, 18]. However, due to technique limitation, accurate in vivo measurement along the entire perimeter of the footplate to measure this is not currently possible.…”