Measurement of the Sustentaculum Tali Range and Biomechanical Screw Analysis Based on the ‘Trabeculae Continental Shelf’ Concept

Abstract Background The sustentaculum tali plays an important role in the surgical treatment of calcaneal fracture. However, there is a lack of relevant literature report on the true extent of the distance process. The introduction of the ‘Continental Shelf’ delineation concept allowed the sustentaculum tali range to be defined with reference to the trabecula topographic trend. Here, we investigated the biomechanical properties of two common sustentaculum tali screws after implantation by applying the finite element method (FEM). Methods Dicom imaging data of the calcaneus sustentaculum tali was obtained by computed tomography (CT)scanning techniques and a spatial three-dimensional (3D) coordinate system was established to measure the extent of the sustentaculum tali. The continuation range was identified according to the trend of the trabecula bone and then superimposed to form a new sustentaculum tali range. Next, by structural design and FEM, we performed biomechanical tests on the two type of sustentaculum tali screws: the ‘pressure type (transverse group)’ test for vertical fracture lines and the ‘tension type (oblique group) of the center’ test. Results Based on the concept of ‘Continental Shelf’ concept, the spatial extent of the sustentaculum tali was redefined. According to FEM calculations, the load bearing capacity of the transverse group was better than that of the oblique group by 15.15% when the screws were implanted in the peak area. Furthermore, the load bearing capacity of the oblique group was better than that of the transverse group by 14.13% and 5.59% when the screws were implanted in the lumbar and valley regions. Conclusions Based on the concept of ‘Continental Shelf’ concept, the range of the sustentaculum tali was expanded. The best mechanical properties of two different screws were implanted in the peak area. The load-bearing capacity gradually reduced when implanted in the lumbar and valley regions. However, the waist area and valley area can still meet the requirements for structural strength and stability, and also provide a good fixation effect. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.