A new measure of tibial sesamoid position in hallux valgus in relation to the coronal rotation of the first metatarsal in CT scans

Kim, Yejeong<sup>1</sup>; Kim, Jin Su<sup>2</sup>; Young, Ki Won<sup>2</sup>; Naraghi, Reza<sup>1</sup>; Cho, Hun Ki<sup>2</sup>; Lee, Sang Young<sup>2</sup>

Affiliations

¹University of Western Australia, Podiatric Medicine Unit/School of Surgery, Faculty of Medicine, Dentistry and Health Science, Corner of Park and Crawley Ave, Perth, WA, Australia

²Eulji Medical Center, Eulji University School of Medicine, Foot and Ankle Clinic, Department of Orthopedic Surgery, Seoul, South Korea

Abstract and keywords

Background: We aimed to find a new radiographic measurement for evaluating first metatarsal pronation and sesamoid position in hallux valgus (HV) deformity.

Methods: Data from a clinical study of 19 control patients (19 feet) with no HV deformity were compared with preoperative data of 138 patients (166 feet) with HV deformities. Using a weightbearing plain radiograph in anteroposterior (AP) view, the intermetatarsal angles (IMAs) and the hallux valgus angles (HVAs) of the control and study groups were measured. Using a semi-weightbearing coronal computed tomography (CT) axial view, the α angle was measured in the control and study groups. In addition, the tibial sesamoid grades in plain radiograph tangential view and the CT axial view were measured. The tibial sesamoid position in an AP view was checked preoperatively. Based on these measurements, 4 types of HV deformities were defined.

Results: The mean values of the α angle in the control and HV deformity groups (control group µ = 13.8 degrees, study group µ = 21.9 degrees) was significantly different. Among 166 HV feet, 145 feet (87.3%) had an α angle of more than 15.8 degrees, which is the upper value of the 95% confidence interval of the control group, indicating the existence of abnormal first metatarsal pronation in HV deformity. Four types of HV deformities were defined based on their α angles and tibial sesamoid grades in CT axial view (CT 4 position). Among 25.9% (43/166) of the study group, abnormal first metatarsal pronation with an absence of sesamoid deviation from its articular facet was observed. The prominent characteristic of this group was that they had high grades in the AP 7 position (≥5); however, in the CT 4 position, their grade was 0. This group was defined as the “pseudo-sesamoid subluxation” group.

Conclusions: Patients with HV deformities had a more pronated first metatarsal than the control group, with a greater α angle. Pseudo-subluxation of the sesamoids existed in 25.9% of our study group. From our results, we suggest that the use of the CT axial view in assessments of HV deformity may benefit surgeons when they make operative choices to correct these deformities. With regard to the pseudo-sesamoid subluxation group, the use of the distal soft tissue procedure is not surgically recommended.

Level of Evidence: Level III, retrospective comparative study.

Keywords: hallux valgus; first metatarsal pronation; sesamoid; CT axial view

Links

DOI: 10.1177/1071100715576994

PubMed: 25813535

WoS: 000359152600010

Cited Works (1)

Year	Entry
1951	Hardy RH, Clapham JCR. Observations on hallux valgus: based on a controlled series. J Bone Joint Surg. 1951;33B(3):376-391.

Cited By (3)

Year	Entry
2016	Katsui R, Samoto N, Taniguchi A, Akahane M, Isomoto S, Sugimoto K, Tanaka Y. Relationship between displacement and degenerative changes of the sesamoids in hallux valgus. Foot Ankle Int. December 2016;37(12):1303-1309.
2018	Campbell B, Miller MC, Williams L, Conti SF. Pilot study of a 3-dimensional method for analysis of pronation of the first metatarsal of hallux valgus patients. Foot Ankle Int. December 2018;39(12):1449-1456.
2021	Clarke AJ. Crista Volume Measured from 3D Reconstruction of Weightbearing CT Scans Shows a Relationship to Sesamoid Station [Master's thesis]. University of Pittsburgh; 2021.