A while back, I wrote a blog on why I rarely recommend first ray cutouts (see http://prolaborthotics.com/Blog/tabid/90/EntryID/113/Default.aspx  ). More recently, a colleague asked if I would recommend a first ray cutout for a pes cavus foot with plantarflexion of the first ray.
Since the entire idea behind this orthosis is to encourage the first ray to plantarflex or, to put it another way, to prevent the first ray from dorsiflexing (as I mentioned in the previous blog), if you plantarflexed the first ray while casting, prescribed a minimum fill and are using an orthotic lab that does not overfill the medial arch of the positive cast, the orthosis should conform well to the arch of the foot and let the first ray plantarflex.
If any of these things do not happen, then the orthosis is likely to gap from the arch. In other words, it will apply more force to the first ray distally and could actually act to dorsiflex the first ray. If this is the situation, then a first ray cutout can be beneficial and allow the first ray to plantarflex.
By plantarflexing the first ray when I cast, commonly prescribing a minimum fill and using an extremely high quality orthotic lab that pays close attention to its cast work, I rarely have to use a first ray cutout on my own orthotic devices.
Sometimes, I do have a patient with cavus foot and plantarflexed first ray who presents and already has a pair of orthoses. If those orthoses do not adequately conform to the foot (and thus allow the first ray to plantarflex), I will often add a first ray cutout to those devices.
Editor’s note: This blog was originally published at http://prolaborthotics.com/Default.aspx?tabid=90&EntryID=489  and has been adapted with permission from Lawrence Huppin, DPM, and ProLab Orthotics. For more information, visit www.prolaborthotics.com  .