Inverted Orthotic Technique: Email Questions

Dear Dr. Blake,

sorry for my bad english,

 I'm an Italian podiatrist; I very interested about inverted technique. I have some questions to ask:

- Is it right to think Fettig modification only with inverted technique? and then, is it only used to correct a forefoot valgus associated with rearfoot varus? if no, when and how?

- Denton and Feehery modification are similar, when apply one or the other?

- In your daily treatment, do you often use these modification?

Thanks for your patience!

Dr Blake's response:

     Thank you for the kind email. I am happy to teach you. Please feel free to take the information I give you and ask any more. I will combine with this posting.  My wife and I hopefully will go to Rome next year on vacation. The Fettig Modification is a modification of the Inverted Technique only and used for the many patients with both a pronation tendency and a supination tendency. The Fettig can only be used in forefoot valgus (everted) feet, as it uses the forefoot valgus correction to be an anti-supination instrument. When the inverted technique controls rear foot pronation, the Fettig can grab that lateral column and slow down or stop mid stance to propulsive phase supination. The supination tendency can come from many causes one of which is rear foot varus, another unstable lateral column, or weak peroneals, or chronic ankle sprains, etc. The Denton modification, her sister lives in Rome, is an extrinsic lateral arch fill that wonderfully fills up the lateral arch  and helps block a supination tendency. The Feehery is an intrinsic raising of the cuboid and lateral anterior calcaneus that does the same, but you cut into the cast. Like the Kirby skive laterally, you have to learn when to violate the cast and when not to. I make orthotic devices as a process typically only violating the cast on the second modification when needed. This is the same general principle I typically use for the Kirby skive.
     Let us say that you have a patient with pronation and supination tendencies. They pronate mainly at contact, but due to chronic ankle instability, love to misstep and supinate at times (typically also at contact). For the pronation, you estimate they need a 30 degree inverted correction. For the supination tendency, they have a forefoot valgus/plantar flexed first ray we can use. So, you order a Fettig. You can also typically add a high lateral heel cup and lateral phalange, a Denton modification, and a full topcover to a forefoot valgus extension under the 4th and 5th metatarsal heads. 
     Let us say that you suspect initially, or you see at dispense, that the patient is not as controlled laterally as you would like. Your next orthotic device will be a lateral Kirby skive to the above cast, a Feehery cuboid skive, or both. And you  can also add more height to the lateral heel cup, and more height to the lateral phalange, along with a bigger forefoot valgus forefoot extension. The possibilities are endless. Please ask other questions. Rich

PS I use the Denton routinely (almost daily) and the Fettig modification 1-2 times per year. I probably use the Feehery once every other month. I relie a lot on stable shoes, lateral phalanges, forefoot valgus extensions.