ABSTRACT
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.