Foot structural factors and ground reaction force in hallux valgus grades

Little attention has been paid to foot structural factors and ground reaction force in hallux valgus. Investigating the structural factors in detail and determining their biomechanical effects can help to better manage hallux valgus.

In this case-control study, 120 females, 90 hallux valgus and 30 healthy, were recruited. Hallux valgus grades (mild, moderate, severe), first metatarsal mobility, foot pronation, hallux rotation, and pain were assessed by clinical tests. Ground reaction forces were measured in barefoot and shod conditions for both feet and analyzed using mixed within-between MANOVA. The association between structural factors and pain with force was analyzed using Spearman correlation coefficient.

The frequency of foot structural factors and pain severity were reported in hallux valgus grades. A significant difference was seen in the force values between groups (P<0.001). Bonferroni post hoc test indicated that the mean of the first peak for the severe group was significantly higher than the mild group (P=0.013) and the mean of second peak for the moderate group was higher than that of the healthy group (P=0.009). The force values were affected by wearing shoe (P<0.001) but not by foot side (P=0.086). There was a medium, positive correlation between the hallux rotation and force in the moderate group (r=0.39, P=0.03) and also between the pronation and force in the severe group (r=0.36, P=0.04).

Foot structural factors, pain, and force were different in each hallux valgus grads. Similar force in both feet, and increased force by wearing shoe were seen. The relationship between the pronation and hallux rotation with force revealed the importance of these factors from the biomechanical viewpoint.