Hello, I'm going to present our work on three-dimensional measurements of the synesthesia and tassel canal in pediatric flexible flat feet deformity using weight-bearing CT scans. I'm Shuyuan Li, one of the co-corresponding authors, and this collaborative work was done by researchers from the University of Colorado, Steps to Walk, and Beijing Tongren Hospital. The authors have nothing to disclose. When the hard foot is in virus and the tassel canal becomes visible on lateral X-rays and has been referred to as a target sign, however, the synesthesia and tassel canal are not easily visible radiographically when associated with a flat foot. The dimensions of both the synesthesia and the tassel canal in normal and flat feet are unknown, but if understood, could help with the design and implantation of an arthritis, which is a commonly performed procedure for correction of pediatric flat foot deformity. And knowing the size of the tassel canal will also reduce post-operative complications of arthritis such as stiffness resulting from too large an implant. So the purpose of this study was to take three-dimensional measurements of the tassel canal in pediatric flat feet under weight-bearing conditions. This was a prospective IRB approved study, and we included pediatric patients with flexible flat feet as a study group, and asymptomatic children without flat feet but came in for other foot and ankle disorders as control group. We used 3D computer-aided design models from weight-bearing CT scans and non-weight-bearing CT scans. So we measured the following parameters, the widest diameter of the posterior medial tassel canal, the narrowest superior-inferior diameter of the tassel canal, the length of the tassel sinus and the length of the tassel canal, and the sinus tassel sinus and tassel canal's volume together, and then correlations between the patient age, height of foot alignment, mirror's angle, and each of the above-measured parameters were investigated. In addition to that, both weight-bearing and non-weight-bearing CT scans were used for study to investigate the effect of bearing weight on the above-mentioned parameters, which were illustrated in Figure 1 and 2. Then we can see in Figure 1 that is the impact of weight-bearing in Figure A, and non-weight-bearing in Figure B, and you can see after the patient in weight-bearing condition and the sinus tassel volume was reduced. And in Figure 2, it illustrates how the 3D reconstruction of a flat foot with internal rotation to demonstrate the dimension of the tassel canal. So, our results showed that 22 children with flexible flat feet with age range between 9 to 14 and 14 children with no flat foot deformities with age 9 to 15 were included. And with weight-bearing, the TSCV decreased by 20% in comparison with non-weight-bearing evaluation, and the volume of the sinus tassel and tassel canal, the widest diameter of the anterior lateral tassel sinus, and the LTC decreased in flat foot, both under weight-bearing and non-weight-bearing conditions compared with the control group. And there is a positive linear correlation was found between the volume of the sinus tassel and tassel canal and the patient's age, while there was negative linear correlations found between the sinus tassel and tassel canal volume at the high foot alignment as well as the mirror's angle. And moreover, the sinus tassel and tassel canal volume significantly decreased in the flat foot group during weight-bearing, while the volume of the tassel canal remained unchanged. That means only mainly the sinus tassel volume has changed. So, here's our conclusion. Although the tassel sinus and canal volume was positively associated with patient's age, there was a negative correlation with the high foot alignment at the mirror's angle. These findings may be very relevant in future studies of the sub-telodont in both children and adults. They clearly have an implication for treatment of the pediatric flat foot with arthritis. Thank you.

three-dimensional measurements

pediatric flexible flat feet deformity

tarsal canal

arthritis procedures

CT scans