Funny, but once the hallux touches the ground during the gait cycle.....it DOES NOT MOVE....but rather the foot moves around the hallux.
As such, how can the hallux drive the metatarsal?
Looking at how the body moves over the foot, both the hallux and 1st met are responding to their ability to either dorsiflex in a timely and normal fashion, or not.
The further the CoM moves beyond the weight bearing foot, the more accommodation is required should timely dorsiflexion fail to occur.
It is the body's movement which drives hallux valgus, and not the other way around.
The problem with the notion here is that they are using position to predict motion or a change in position.
Developement of HAV is a change in position of the the hallux and first metatatarsal.
Snijders showed that a flexion moment at the first MPJ increases the intermetatarsal angle.
They showed this with use of the flexor hallucis longus muscle. There are also passive structures that will create a plantar flexion moment at the MPJ (plantar fascia).
The plantar flexion moment at the mpj is created by a proximal pull on the hallux and a distal push from the metatarsal head acting on the base of the proximal phalanx.
The equal and opposite force of the base of the proximal phalanx pushing on the metatarsal head can push the metatarsal to increase the intermetatarsal angle.
So, yes the hallux could be said to drive the deformity, but not for the reasons that the above article suggests.
A reappraisal of the relationship between metatarsus adductus and
hallux valgus
Chen Li, Wang Chen, Wang Xu, Huang Jiazhang, Zhang Chao, Zhang Yijun and Ma Xin Chinese Medical Journal 2014;127 (11) 2067
Assessing the Rotation of the First Metatarsal on Computed Tomography Scans: A Systematic Literature Review
Ali-Asgar Najefi, FRCS (Tr&Orth), Karan Malhotra, FRCS (Tr&Orth), Shelain Patel, FRCS (Tr&Orth), ... Foot & Ankle International June 24, 2021