Jan 18

Written by: Larry Huppin, DPM
1/18/2010 3:03 PM

When the rearfoot everts, the medial forefoot is forced into the ground. This results in a dorsiflexion force on the first ray and jamming of the first 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. Paul D. Harradine, MSc, and Lawrence S. Bevan, BSc (Hons), did a preliminary study on "The Effect of Rearfoot Eversion on Maximal Hallux Dorsiflexion." They found that hallux dorsiflexion is decreased 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:

• Wide orthotic shell to put more orthotic surface area medial to the axis of the STJ
• Deep heel cup
• Add 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 
• Prescribe a Reverse Mortons 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).  If you have any questions on proper casting technique, watch our casting video.

*Paul D. Harradine, MSc, SRCh, CertEd, and Lawrence S. Bevan, BSc (Hons), SRCh. The Effect of Rearfoot Eversion on Maximal Hallux Dorsiflexion: A Preliminary Study. Journal of the American Podiatic Medical Association, Pg. 390, Volume 90, Number 8, September 2000.

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