Modifying Orthotics To Resist Rearfoot Eversion In Hallux Limitus

When the rearfoot everts, it forces the medial forefoot into the ground. This results in a dorsiflexion force on the first ray and jamming of the first metatarsophalangeal joint (MPJ) as the patients begins to toe-off.

An article published several years ago in the Journal of the American Podiatric Medical Association gives us some good data on this relationship.¹ Harradine and Bevan did a preliminary study on the effect of rearfoot eversion on maximal hallux dorsiflexion, finding that hallux dorsiflexion decreases with rearfoot eversion.

This again underscores the importance of prescribing rearfoot control when treating hallux limitus. To resist rearfoot eversion, your orthotic prescription should contain:

• a wide orthotic shell to put more orthotic surface area medial to the axis of the subtalar joint;
• a deep heel cup;
• an additional 4 mm or 6 mm medial heel skive to the positive cast (this ultimately reduces the ground reactive force on the first ray, allowing greater dorsiflexion of the hallux); and 
• a reverse Morton’s extension (this also allows the first ray to plantarflex).

Proper negative casting is critical. Be sure to plantarflex the first ray or dorsiflex the hallux to resistance during casting.

Reference

1. Harradine PD, Bevan LS. The effect of rearfoot eversion on maximal hallux dorsiflexion: a preliminary study. J Am Podiatr Med Assoc. 2000; 90(8):390-3.

Editor’s note: This blog was originally published at

https://www.prolaborthotics.com/Blog/tabid/90/EntryID/130/Default.aspx .