Hello, my name is Andrew Behrens. Thank you for taking the time to listen to my presentation. Today I will be speaking about the relationship between the longitudinal axis of the intersesamoid crista and the distal metatarsal articular angle in patients with hallux vagus. Disclosure slide. Little is known about the intersesamoid crista in hallux vagus. The structure directly interfaces with the sesamoids and surrounding soft tissues and might play an important role in hallux vagus deformity. Our primary objective was to compare the angulation between the crista and first metatarsal longitudinal axis in hallux vagus and controls. Our secondary objective was to assess its correlation with the distal metatarsal articular angle. We hypothesized that the longitudinal axis of the crista will be deviated in hallux vagus and that its position will be correlated with the distal metatarsal articular angle. This IRB-approved retrospective case control study evaluated a total of 17 cases, 9 of which were hallux vagus and 8 of which were controls. These cases were matched on age, BMI, and gender. The distal metatarsal articular angle was measured on 2D x-rays and then on weight-bearing CT using a previously validated technique. This technique is referred to as 3D DMMA-DMAA and is the subject of a 2022 paper. CT scans were segmented using DZOR, a semi-automated segmentation software, to create 3D models of the forefoot. The crista was selected in Geomagic Design X and the resulting STL models were exported into MATLAB for analysis. Vertical component analysis was used to identify the direction of both the crista and the first metatarsal shaft. The crista-shaft angle is the angle between the axis of the crista, shown in purple, and the axis of the first metatarsal, shown in green. This angle is calculated in the direction of greatest variation. The crista deviated from the angle of the first metatarsal shaft in valgus in all cases, both in hallux valgus and in controls. However, there was a significant increase in valgus deviation of the crista in hallux valgus when compared to the controls. The controls, left in blue, had a mean deviation of 5.5 degrees and the hallux valgus, right in red, had a deviation of 14.4 degrees. This difference was found to be statistically significant with a p-value of 0.017. The mean 2D distal metatarsal articular angles, as measured on x-ray, were 25.1 degrees in hallux valgus and 7.4 in controls. This difference was found to be statistically significant with a p-value of less than 0.001. The mean 3D distal metatarsal articular angles, as measured on weight-bearing CT, were 12.5 degrees in hallux valgus and 3.1 degrees in controls. This difference was found to be statistically significant with a p-value of less than 0.001. There was a low positive, non-significant correlation between the crista deviation and the 2D distal metatarsal articular angle. However, there was a moderate positive correlation between the angle of the crista 1st metatarsal angle and the 3-dimensional distal metatarsal articular angle. This p-value was 0.017. The longitudinal axis of the intersezymloid crista deviates from the 1st metatarsal shaft in valgus when compared to the controls. This follows the pattern of the 3-dimensional distal metatarsal articular angle, which reflects the valgus deviation of the articular surface after exclusion of the pronation. This is an important compounding factor of the original DMAA measurement technique that the 3D DMAA measurement technique addresses. The intersezymloid crista may play a role in hallux valgus pathophysiology as a possible lateral destabilizer of the surrounding soft tissues in hallux valgus. Surgically correcting the distal metatarsal articular angle with a distal osteotomy might also correct the crista position in hallux valgus. Thank you very much for your time. My email is andrew-barrants at uiowa.edu. Please reach out to me if you have any questions or would like to learn more. Thank you very much.

Andrew Behrens

longitudinal axis

intersesamoid crista

distal metatarsal articular angle

hallux vagus