The first metatarsal cutout or first ray cutout is a common orthotic modification clinicians use to allow the first ray to plantarflex in order to treat functional hallux limitus. I think it should be noted, however, that if a practitioner takes extremely good negative cast, writes an appropriate prescription, uses an orthotic lab and does not overfill the medial arch, the first ray cutout should rarely be necessary.
The orthosis goal in the presence of functional hallux limitus is to allow the first ray to plantarflex. One can accomplish this by plantarflexing the first ray while taking the negative casts, prescribing a minimum cast fill with approximately 2 to 3 degrees of inversion and ensuring that your orthotic lab does not overfill the medial arch.
When podiatrists have achieved these objectives, the first ray should plantarflex quite effectively in order to decompress first MPJ motion and enhance a windlass function. Making an orthosis in this manner will help ensure that it conforms very closely to the arch of the foot when the foot is held in neutral position with the first ray plantarflexed. It should conform closest posteriorly and flare away from the foot anteriorly.
As all of the doctors in my clinic follow these guidelines when treating functional hallux limitus, we never prescribe first ray cutouts.
I do, however, use first ray cutouts in my office on occasion. The most common time I do so is when the patient comes in with an orthosis received from another practitioner and the orthotic device does not conform very close to the arch of the foot. In this situation, with the foot having to flatten and the first ray having to elevate in order to reach the orthosis, I want to somehow enhance plantarflexion of the first ray. The first ray cutout or first metatarsal cutout, along with a reverse Morton’s extension, is a good option in this situation.
Editor’s note: This blog was originally published at http://www.prolaborthotics.com/Blog/tabid/90/EntryID/438/Default.aspx  and has been adapted with permission from Lawrence Huppin, DPM, and ProLab Orthotics. For more information, visit www.prolaborthotics.com  .