Prescribing An Orthotic For A Patient With Bilateral Midtarsal Joint Arthritis

A colleague recently called about a patient with bilateral midtarsal joint arthritis. In this case, the goal is fairly simple. We want to limit midtarsal joint motion and in doing so reduce the patient’s pain.

The patient has moderate arch collapse. She also has a heel that is everted by about 8 degrees in stance. Accordingly, one would try to control the arch and hopefully limit some of the rearfoot eversion. The following is what I recommended for an orthotic prescription for this patient.

Direct milled, semi-rigid polypropylene shell.

Deep heel cup.

Wide width. We want the device wide so the surface area of the orthosis is under the entire midtarsal joint.

Minimum cast fill. This enables the orthosis to conform closely to the arch of the foot to help limit midtarsal joint motion. 

Medial heel skive of 4 mm. This helps limit rearfoot eversion.

Positive cast inversion of 2 degrees. This will result in an orthosis with a slightly higher arch but more importantly, the arch will increase at the calcaneal inclination angle, which should help limit midtarsal joint motion. 

Polypropylene rearfoot post of 0/0. Of course, the only type of rearfoot post that we can put on a direct milled orthosis is polypropylene. 

A topcover is not necessary for this pathology. However, you can add one if you feel the patient would benefit from some cushion.

Editor’s note: This blog was first published at https://www.prolaborthotics.com/ClientServices/ClientsOnlyArea/AdvancedPSOIndex/MidtarsalJointArthritis/tabid/266/Default.aspx and has been adapted with permission from Lawrence Huppin, DPM, and ProLab Orthotics. For more information, visit www.prolaborthotics.com .