Key Orthotic Principles For Resisting Rearfoot Eversion In Patients With Hallux Limitus

Rearfoot eversion 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 patients begin 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 studied the effect of rearfoot eversion on maximal hallux dorsiflexion and found 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 incorporate:

• a wide orthotic shell to put more orthotic surface area medial to the axis of the subtalar joint;
• a deep heel cup;
• the addition of a 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. Plantarflex the first ray or dorsiflex the hallux to resistance during casting (this plantarflexes the first ray).

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 first published at https://prolaborthotics.com/Blog/tabid/90/EntryID/130/Default.aspx and has been adapted with permission from Lawrence Huppin, DPM, and ProLab Orthotics. For more information, visit www.prolaborthotics.com .