CT anatomical features of the sustentaculum fragment and their clinical significance / 中华创伤骨科杂志

Objective:To determine the anatomical parameters concerning the length, width and height of the sustentaculum fragment of the calcaneus using CT imaging data and their clinical significance.Methods:A retrospective study was conducted to analyze the CT imaging data of normal calcaneus in 96 patients (100 feet) which had been collected by Department of Orthopedics, Shanghai Tongji Hospital from January 2019 to September 2020. There were 45 males (48 feet) and 51 females (52 feet) with an age of (42.1±13.6) years, and 56 left feet and 44 right feet. After 3D models were reconstructed with the CT data using software Mimics 22.0, the calcaneus was viewed layer by layer at each level of the scan. After the first continuous bone trabecula on the medial side of the calcaneal central triangle was taken as the boundary, the model of the sustentaculum fragment was segmented. The length, width, and height of the sustentaculum fragment were measured. The outer contour of the sustentaculum fragment was projected onto the lateral wall of the calcaneus to draw the contour line using software Materialise 3-Matic 22.0. By overlaying projection line diagrams, a summary of projection line diagrams of 100 sustentaculum fragments was obtained. Seven screw insertion points were selected in the summary region of the projection line diagrams of the lateral wall of the calcaneus, and the distance from each point to the medial side of the calcaneus were measureed. The length, width, and height of the sustentaculum fragment, as well as the distance from the 7 insertion points to the medial side of the calcaneus, were compared between different feet and genders.Results:The length, width, and height of the sustentaculum fragment were (45.19±4.60) mm, (38.57±4.59) mm and (40.76±5.48) mm, respectively. There were no significant differences in the length, width or height of the sustentaculum fragment between different feet or in the height of the sustentaculum fragment between different genders ( P>0.05), but the length and width of the sustentaculum fragment in females were significantly smaller than those in the males ( P<0.05). The projection of the sustentaculum fragment was approximately ellipse on the summary region of the projection line diagrams on the lateral wall of the calcaneus, with the long axis approximately parallel to the midpoint tangent of the lateral edge of the calcaneal posterior articular surface, ranging from 2 to 20 mm from the posterior articular surface. The distances from the 7 insertion points to the medial surface of the calcaneus were (39.91±3.77) mm at point A, (40.89±3.55) mm at point B, (36.42±5.98) mm at point C, (39.12±5.52) mm at point D, (40.04±4.84) mm at point E, (33.00±3.96) mm at point F, and (33.04±3.82) mm at point H. There was no significant difference in the distances from the 7 insertion points to the medial surface of the calcaneus between different feet ( P>0.05), but the distances from the 7 insertion points to the medial surface of the calcaneus in the females were significantly smaller than those in the males ( P<0.05). Conclusions:Anatomical measurements of the sustentaculum fragment can provide a theoretical basis for the range of fixation of the sustentaculum screws. A summary of projection line diagrams of the sustentaculum fragment on the lateral surface of the calcaneus can serve as a reference for placement of sustentaculum screws. Measurement of the distances from 7 insertion points to the medial surface of the calcaneus can facilitate determination of the lengths of sustentaculum screws.

An applied research on precise sustentacular screw placement based on anatomical division of the anterior lateral wall of calcaneus and the sustentaculum tali / 中华创伤骨科杂志

Objective:To evaluate our novel path based on anatomical division of the anterior lateral wall of calcaneus and the sustentaculum tali for precise sustentacular screw placement in the surgical treatment of calcaneal fractures of Sanders types Ⅱ and Ⅲ.Methods:The anterior lateral wall of the calcaneus was divided into the anterior-superior zone S 1, the anterior-inferior zone S 2, the posterior-superior zone S 3 and the posterior-inferior zone S 4 for demarcation of the screw insertion points by our method of Four Zones, and into the front, middle and rear sections by our method of Three Sections for demarcation of the screw target points. The specimens were scanned by CT and modeled by Mimics. On the 3D virtual model of the calcaneus, one screw was placed from each zone of the anterior lateral wall of the calcaneus to the sustentaculum tali body. The screw placement target for S 1 and S 2 was the medial intersection point P 1 of the front and middle sections of the sustentaculum tali, and that for S 3 and S 4 was the medial intersection point P 2 of the middle and rear sections of the sustentaculum tali. It was observed whether the screws were placed in the bone channel. A total of 72 patients were included who had been admitted to Department of Orthopaedics, Suqian Hospital Affiliated to Xuzhou Medical University for calcaneal fractures of Sanders types Ⅱ and Ⅲ from January 2017 to January 2021. They were divided into an anatomical division group and a 3D printing group according to their screw placement method for the sustentaculum tali. In the anatomical division group of 32 patients subjected to screw placement based on our anatomical division, there were 25 males and 7 females, aged from 24 to 60 years; in the 3D printing group of 40 patients subjected to screw placement assisted by 3D printing, there were 31 males and 9 females, aged from 25 to 58 years. The disparities between the parameters of sustentacular screw placement and the actual values were compared in the anatomical division group, and the total number of screws, screws on average, distribution of screws, and accuracy of screw placement were compared between the 2 groups. Results:All the screws which were virtually placed in the specimens of the calcaneus from S 1 and S 2 to P 1 and from S 3 and S 4 to P 2 passed through the bony channel, with no perforation into the tarsal sinus. There was no significant difference in the general date between the anatomical division group and the 3D printing group, showing they were comparable ( P > 0.05). In the anatomical division group, a total of 52 screws were placed to the sustentaculum tali with an average of (1.63 ± 0.48) screws per patient, and 2 screws were placed in 20 patients, yielding an accuracy rate of screw placement of 92.3% (48/52). There were no statistically significant differences between the parameters and the actual values of screw placement in the anatomical division group ( P > 0.05). In the 3D printing group, a total of 63 screws were placed to the sustentaculum tali with an average of (1.58 ± 0.49) screws per patient, and 2 screws were placed in 23 patients, yielding an accuracy rate of screw placement of 93.7% (59/63). There were no significant differences in the above comparisons between the anatomical division group and the 3D printing group ( P > 0.05). Conclusion:In the surgical treatment of calcaneal fractures of Sanders types Ⅱ and Ⅲ, the sustentacular screw placement based on our anatomical division of the anterior lateral wall of the calcaneus and the sustentaculum tali can lead to similar clinical accuracy as 3D printing-assisted screw placement does.

Anatomic classification of the sustentaculum tali and its characteristics analysis / 解剖学报

Objective To explore the anatomical morphology and characteristics of the sustentaculum tali based on CT three⁃dimensional reconstruction, so to provide anatomical support for the treatment of calcaneal fractures with screw implantation. Methods From March 2019 to March 2020, a total of 336 adult calcaneal CT three⁃dimensional reconstruction images from the Affiliated Hospital of Traditional Chinese Medicine of Southwest Medical University were collected after exclusion of inclusion criteria. The CT three⁃dimensional reconstruction of calcaneus was classified according to the β, the prolate axial intersection between sustentaculum tali and calcaneus on the normal posterior. Reference points, β; AB, the distance from the inside of sustentaculum tali to the inside of posterior talar articular surface; AC, the distance from the inside of sustentaculum tali to the outside of posterior talar articular surface; AD, the distance from the inside of sustentaculum tali to lateral of calcaneal; AE, the distance from the inside of sustentaculum tali to medial process of calcaneal tuberosity; AF, the distance from the inside of sustentaculum tali to calcaneal tuberosity; AG, the distance from the inside of sustentaculum tali to lateral process of calcaneal tuberosity. The results were statistically analyzed according to type, sex and body side. Results Under the β, the sustentaculum tali was classified into three types: typeⅠ(β<70°, 68 cases, 20.24%), type Ⅱ(70°≤β<80°, 153 cases, 45.54%), type Ⅲ(80°≤β<90°, 115 cases, 34.23%). For the distance of β, AB, AF, there were statistical differences between type Ⅲ and other types (P<0.05). For the distance of AE, there were statistical differences between type Ⅲ and typeⅠ(P<0.05). Meanwhile, for the distance of AB, AC, AD, AE, AF, AG, there were statistical differences between male and female (P<0.05). For the distance of β, AB, there were statistical differences between right and left (P<0.05). Conclusion Under the β, the sustentaculum tali is classified into three types, with the typeⅡas the main type. When treating calcaneal fractures with internal fixation, direction of screw implant can choose between 70° to 80° as soon as possible. The morphology and classification of sustentaculum tali are of certain clinical implication to treat calcaneal fractures.

Anatomy of the safe zone of sustentaculum tali screw fixation / 解剖学报

Objective To explore the safe zone of sustentaculum tali screw fixation in treatment of calcaneal fracture. Methods Morphologies of sustentaculum tali in intact dry calcaneus of 589 Chinese adult were investigated and classified. The clinically significant data were observed and measured in sustentaculum tali and calcaneus. Results Type B calcaneus (77. 92%) was defined as the most common type, and type A calcaneus (21. 73%) was the second most common type. There were two osseous marks in the medial surface of sustentaculum tali: the posterior tip of middle articular surface for talus and the front end of medial margin of groove for flexor hallucis longus. In the medial of sustentaculum tali, the each side length of quadrilateral was (8. 07±1. 33)(3. 88-12. 31)mm, (10. 27±1. 57)(5. 62-15. 91) mm, (14. 99± 2. 33) (5. 86-21. 87) mm and (15. 43±2. 16) (9. 82-22. 70) mm, respectively. The length of the its diagonal line was (15. 83±2. 94) (3. 83-26. 59) mm. The length of middle articular surface for talus was (18. 97±2. 85)mm (9. 90-25. 41). Conclusion The quadrilateral in the medial surface of sustentaculum tali is the safe zone for sustentaculum tali screw fixation in treatment of calcaneal fracture.

Study on sustentaculum tali screw placement for constant fragment of calcaneal fracture / 中国修复重建外科杂志

Objective: To investigate the anatomical characters of the sustentaculum tali (ST), accurate entry point and direction for the placement of ST screw from posterior subtalar joint facet to the constant fragment (CF) in calcaneal fractures. Methods: A total of 100 patients with calcaneal fractures performed ankle CT scans were enrolled between January 2016 and April 2016. According to the inclusion criteria, the clinical data of 33 patients were analyzed, including 18 males and 15 females, with a median age of 41.0 years (range, 18-60 years). There were 16 cases on left side and 17 cases on the right side. Three-dimensional (3D) calcaneal model was reconstructed by Mimics 17.0 software, and the ST anatomical references were measured, including the length of upper and lower edge, the length and height of the midline, the horizontal angle between the midline and foot plantar surface. The parameters of the optimal entry point position (P' point) and placement angle of the ST screw were determined. The length of ST screw was also measured. The differences between males and females or left and right sides were compared. Results: The length of upper edge of the ST was (16.60±2.23) mm, lower edge (20.65±2.90) mm, midline (20.56±2.62) mm, and the height of midline was (9.61±1.36) mm. The horizontal angle between the midline and foot plantar surface was (23.43±3.36)°. The vertical distance from P' point to the lowest point of the tarsal sinus was (3.09±1.65) mm, while the horizontal distance was (14.29±2.75) mm. The distance from P' point to the apex of the lateral talus, subchondral bone of subtalar joint, calcaneocuboid joint was (11.41±3.22), (6.59±2.22), (34.58±3.75) mm, respectively. The horizontal angle between the ST screw and foot plantar surface was (-1.17±2.07)°. The anteversion angle of ST screw was (16.18±2.05)° and the length was (41.64 ± 3.09) mm. There were significant differences in the length of upper and lower edge, the length and height of the midline, the distance from P' point to the apex of the lateral talus, subchondral bone of subtalar joint, and calcaneocuboid joint, and the anteversion angle and length of the ST screw between males and females ( P0.05). Conclusion: After appropriate reduction of the calcaneal fractures, the entry point of ST screw was recommended at about 14 mm posterior and about 3 mm upper related to the foot horizontal line through the lowest tarsal sinus point; and the direction of ST screw placement was about 17° anteversion for males and 15° anteversion for females.

Study on using CT to locating mark of sustentaculum tali and the parameter measurement / 重庆医学

Objective To use CT and 3D reconstruction technique to locating mark of sustentaculum tali ,and measure the an‐gle & length of the specified point of the lateral wall of the calcaneus to sustentaculum tali for providing .To basis for the operation of calcaneus .Methods Thirty adult ankle wet specimens were chosen and scanned with CT ,and the dicom data were converted into the software to 3D‐reconstruction ,the observation and measurement to find new methods of locating mark of sustentaculum tali ;Forty adult calcaneus dried specimens were chosen and scanned with CT .The dicom data were converted into the software to 3D‐re‐construction ,using a workstation software measure the angle and length of the line which from the center of the sustentaculum tail to each point on the calcaneal lateral wall .Results First ,in the function of ankle joint position ,with the foot medial surface as “sag‐ittal reference plane” measurement ,the vertical line passing through the leading edge of medial malleols and the coronal line passing through the leading edge of sustentaculum tali intersect at a point .The vertical distance of the point to leading edge of medial malle‐ols was (34 .95 ± 2 .60) mm ,the length of sustentaculum tali was (21 .44 ± 1 .89) mm ,the height of sustentaculum tali was (10 .17 ± 1 .16) mm ,the anteversion of sustentaculum tali was (35 .31 ± 3 .73)° .Second ,in front of calcaneus ,upward angel of points G ,E were (28 .78 ± 3 .90 )° ,(29 .47 ± 2 .96 )° respectively .Frontward angle of points G ,E were ( - 19 .83 ± 4 .60 )° , ( - 11 .02 ± 4 .74)° respectively .Under the posterior articular surface ,upward angel of points C ,K ,I ,J were(2 .52 ± 2 .46)° ,(2 .92 ± 2 .28)° ,(14 .98 ± 2 .49)° ,(14 .38 ± 1 .90)° respectively .Frontward angle of points C ,K ,I ,J were(7 .32 ± 1 .66)° ,(19 .25 ± 1 .98)° , (10 .30 ± 2 .63)° ,(19 .33 ± 1 .97)° respectively .The length of screw was about 40 - 44 mm .The length of C point to the sustentacu‐lum tail was minimum ,and the length of G was maximum .Conclusion In the function of ankle joint position ,the sustentaculum tail can be located with the leading edge of medial malleols as a surface landmarks .The measurement of the angle and length of which from each point on the calcaneal lateral wall to sustentaculum tail by using CT .

Concomitant Fracture of the Lateral Process of the Talus and the Sustentaculum Tali of the Calcaneus / 대한정형외과학회잡지

Concomitant fracture of the lateral process of the talus and the sustentaculum tali of the calcaneus is a rare injury. There are few references in the literature that comment on the precise injury mechanism and the operative method for this type of fracture. We achieved satisfactory clinical results in 2 cases of concomitant fractures of the lateral process and the sustentaculum tali resulting from traffic accidents. We used a method of open reduction and internal fixation. We report these cases with a review of the relevant foreign literature because of no previous report in Korean literature.