Imaging anatomic study on axial X-ray projection of sustentaculum tali

Abstract

Objective To explore the axial X-ray projection technique of sustentaculum tali for observing the effect of screw implantment of calcaneal fractures. Methods Forty-five adult specimens of ankle and foot (specimen group) were chosen to research by X-ray, multi-slice spiral computed tomography(MSCT) scan and reconstruction on ankle and foot, and then they were dissected and observed . From July 2014 to June 2017, the People's Hospital of Suqian, a total 225 patients (X-ray group) with lateral X-ray image of ankle and foot were collected and analyzed, retrospectively, there were 132 male patients and 93 female patients, with an average age of 42.6±11.7(range from 18 to 72 years old). Morphological characteristics of sustentaculum tali on specimen were observed with the aid of traditional dissecting methods and MSCT 3D images. The anatomic relationship between sustentaculum tali with the medial malleolus, talus and navicular bone were analyzed. The influencing factors of the axial X-ray projection effect of sustentaculum tali from medial malleolus, talus and navicular bone were studied. The plantar plane was used as anatomical reference plane, the length, the width, the height and anteversion angle of sustentaculum tali were measured. The sustentaculum tali's anteversion angles of male and female patients on X-ray image were also measured. The difference of anteversion angles between each group was compared. The relation between the anteversion angle and the axial projection angle of sustentaculum tali was analyzed, and the X-ray axial projection angle of sustentaculum tali was determined. Five cases of specimen group were randomly used for experimental screw placement. From January 2017 to June 2017, 10 patients with calcaneal fracture were surgical screw internal fixation, and the effect of screw implantment into sustentaculum tali was analyzed by using the axial X-ray projection technique of sustentaculum tali. Results Specimen dissection and MSCT 3D images observation showed that sustentaculum tali located on the medial side of calcaneus, above the anterior part of calcaneus and extended the medial surface, and it had a close anatomical relationship with medial malleolus, talus and navicular bone. However, in the axial direction of sustentaculum tali, only the posterior apophysis of talus was overlapped with sustentaculum tali, which influenced the effect of the axial X-ray projection of sustentaculum tali. The length, width, and height of sustentaculum tali on specimens were (24.36±2.25)mm, (14.91±1.58)mm, and (11.03±1.24)mm. The anteversion angles of sustentaculum tali on specimens were 30.38°±1.21° in anatomical measurement group, 30.47°±1.54° in MSCT measurement group and 30.17°±1.44° in X-ray measurement group, respectively. The sustentaculum tali's anteversion angles of X-ray groups in male and female were 30.09°±1.82° and 30.52°±1.62°, respectively. There was no significant difference of anteversion angles between each group (F=1.768, P>0.05), which showed that different research methods obtained consistent results. The sustentaculum tali's anteversion angle was about 30°, and this angle was the axial X-ray projection of sustentaculum tali. Using the axial X-ray projection to detect the screw inserted into sustentaculum tali, which achieved satisfactory effect. Conclusions The axial X-ray radiography of sustentaculum tali can display the anteroposterior image of sustentaculum tali in long axis direction, and it also can show middle talar articular surface. This radiologic method can be used to the intraoperative X-ray fluoroscopy and the postoperative X-ray radiography for analyzing the effect of internal fixation with screw insertion of calcaneal fracture, which provides new perspectives for related clinical imaging findings of sustentaculum tali. Key words: Calcaneus; Fractures, bone; Anatomy, regional; Sustentaculum tali; Axial view; X-ray projection; Radiography