Correlation between first tarsometatarsal joint sagittal mobility and hallux valgus combined with transfer metatarsalgia

Abstract

Objective: To investigate the correlation between the first tarsometatarsal joint (TMT1) sagittal mobility and hallux valgus (HV) combined with transfer metatarsalgia (TM). Methods: The weight-bearing CT (WBCT) imaging data of 111 HV patients (167 feet) who were treated at the Foot and Ankle Surgery Center, Beijing Tongren Hospital Affiliated to Capital Medical University from January 2018 to January 2020 were retrospectively analyzed. The patients underwent PedCAT WBCT scans of both feet, and the hallux valgus angle (HVA), intermetatarsal angle (IMA), plantar distance (PD), medial cuneiform-first metatarsal angle (CMA) and metatarsal protrusion distance (MPD) were measured using CubeVue software. PD and CMA were signs of TMT1 instability. Visual analogue scale (VAS) and foot and ankle ability measures (FAAM) scores were obtained. The patients were divided into TM group and non-TM group according to the presence of metatarsalgia. The TM group and the non-TM group were compared in terms of HVA, IMA, PD, CMA, MPD, VAS and FAAM. Correlations between PD, CMA and HVA, IMA, VAS, FAAM were analyzed using Spearman correlation. Results: Total of 111 cases were included in this study, there were 35 males and 76 females with a mean age of (57.7±14.1) years. The average values of HVA (37.9°±8.6°), IMA (17.9°±2.6°), CMA (2.1°±0.3°) and PD [(1.8±0.4) mm] in TM group were all significantly higher than those in the non-TM group [HVA (32.5°±9.1°), IMA (15.1°±3.4°), CMA (1.7°±0.3°) and PD (1.6±0.2) mm] (All P<0.001). There was no significant difference in MPD between the two groups (P=0.580). The TM group demonstrated a higher VAS score when compared with the non-TM group (P<0.001). The FAAM score of the TM group (54.1±11.8) was significantly lower than that in the non-TM group (66.2±11.4) (P<0.001). The results of Spearman correlation analysis showed that there was no correlation between PD and HVA, IMA and VAS score. There was a negative correlation between PD, CMA and FAAM score, and the difference was statistically significant (rs=-0.637, -0.254, both P<0.001); CMA was positively correlated with HVA, IMA, and VAS score (rs=0.603, 0.971, 0.269, all P<0.001). Conclusions: WBCT is helpful for the diagnosis of TMT1 sagittal instability. The severity of TMT1 sagittal instability is positively correlated with hallux valgus and TM. The TMT1 instability may play an important role in the pathogenesis of hallux valgus.