First Ray Kinematics in Women With Rheumatoid Arthritis and Bunion Deformity: A Gait Simulation Imaging Study

Abstract

Objective. The first ray plays a role in the development of bunion foot deformity, but for unknown reasons. This prospective, cross-sectional study investigated first ray kinematics in women with rheumatoid arthritis (RA) and bunion. Methods. Nine participants having RA-bunion were analyzed in comparison to a control group (n ‫؍‬ 10). Data were acquired using a magnetic resonance scanner. Conditions were standardized to simulate gait midstance, heel off, and terminal stance. Foot posture (hallux angle, intermetatarsal angle, arch angle, and calcaneus angle) and relative first ray position angles/helical axis parameters registered across gait conditions were measured. An analysis of variance model compared data between groups and across conditions, and correlation assessed the relationship between selected variables. Results. Eversion of the calcaneus averaged 9°, and adduction of the first ray was increased (F ‫؍‬ 6.29, P ‫؍‬ 0.02) by >4.6°a cross conditions in the RA-bunion group. There was an interaction (F ‫؍‬ 7.73, P ‫؍‬ 0.01) for the first ray axis. Followup comparisons identified increased inclination of the first ray axis over middle stance compared to late stance in the group with RA and bunion. There was moderate correlation (r ‫؍‬ ؊0.42) between the calcaneus angle of eversion and inclination of the first ray axis. Conclusion. Optimal treatment for bunion has not been defined. This research identified calcaneus eversion and first ray adduction, as well as inclination of the first ray axis as risk factors of bunion. This result may inform the evaluation and treatment of bunion in women with RA.

An Imaged-Based Three-Dimensional Study of First Metatarsal Protrusion Distance in Women with and Without Hallux Valgus

“…[27][28][29][30][31][32] The weightbearing images were acquired from 2008 to 2010. Nineteen of the women had hallux valgus, 29,31,32 as defined by an enlarged hallux angle. A screening measurement of a hallux angle larger than 15 degrees served as the threshold for indicating deformity.…”

“…Nine women with hallux valgus also had rheumatoid arthritis. 29 Control participants (n ¼ 10) were group-matched by age. A more thorough description of the inclusion criteria and demographics of the participants have been reported.…”

“…A more thorough description of the inclusion criteria and demographics of the participants have been reported. 29,31,32 Consent was obtained at time of enrollment, and this review of the images was performed in accordance with University of Minnesota Institutional Review Board (#1404E49482) guidelines.…”

“…Participants were positioned with weight distributed on both feet, 29,31 and with their ankle joints dorsiflexed 5 degrees to simulate standing. 33 The scan field, composed of 128 slices, was centered to capture the entire foot and ankle.…”

“…Further details of the scanning protocol have been reported elsewhere. 9,29,31 Images were imported into Mimics 17.01 (Materialise, Leuven, Belgium) software for reconstruction. The virtual bone models displayed for analysis in this study were the first metatarsal, second metatarsal, and navicular.…”