If the feet bones can increase in length after epiphyseal fusion perhaps we can use the mechanisms which increase foot length on the long bones.
Gender and age related differences in foot morphology
“Anatomical parameters such as foot length, circumference and height and ankle length, circumference and height were assessed in a sample of males and females divided into three age groups. The groups included young-adult, aged between 20 and 25 years; adult, aged between 35 and 55 years; and old, aged between 65 and 70 years individuals.”
“Comparative analysis of morphometric data between young-adult and adult individuals revealed that the instep length was smaller in adults. The opposite was observed for the great toe and medial foot arch height. Length of ankle was higher in adult than in young-adult individuals, whereas ankle circumference and height were smaller.”<-I don’t know what conclusions to possibly draw from this but there could be something to gather here.
“From a topographic anatomy point of view, foot is in general divided into three parts, namely forefoot, midfoot and hindfoot. The forefoot includes the five toes (phalanges) and the five longer bones (metatarsals). The midfoot represents a pyramid-like association of bones (cuneiform, cuboid and navicular bones) forming the arches of the feet. The hindfoot includes the heel (calcaneus) and the ankle. The heel bone is the largest bone of the foot, whereas the talus bone supports the leg bones (tibia and fibula), forming the ankle”
“The elderly is reported to have flatter, longer, and wider feet than younger adults“<-Taken from Age-related differences in foot structure and function. Although I could not find the information that elderly feet tended to be longer from that study. They state in regards to this study “Other investigations enlarging their analysis to old people aged 80.2 ± 5.7 years noticed in the elderly group compared with a younger one of the mean age of 20.6 ± 2.6 years flatter, longer, and wider feet than younger adults”
The other citation they use for this is: Foot Health and Shoewear for Women. And I can’t find anything compelling here other than a statement that a woman’s foot grows larger with age.
“The foot length was measured between the extreme point of heel (foot end) and the extreme point of the longest toe (either first or second toe).”
“The ankle height was considered as the distance between the heel of foot and the line right above the medial malleolus.”
Average foot length of age 35-55 was 269.2 cm and 261.7cm for age 20-25 cm male group. Foot length was similarly longer for the female middle age versus young adults group. In males age 65-70 Foot Length was 264.4 cm which is a decrease for middle age but the female group continued to increase in foot length.
So we can’t really conclude that foot length continues to grow with age but this indicates that it may be possible that the feet do grow.