Posterior Tibial Tendonitis (PTT) often correlates with a pes valgo planus foot type, leading to excessive strain on the tendon. While some might focus solely on strengthening the tendon, it's crucial to address the underlying foot structure.
Inversion modifications include extrinsic and intrinsic inversion techniques. Most clinicians are familiar with an extrinsic inverted rearfoot post. For severe cases, it is typical to see posting from 4-8 degrees of Varus. One limitation of the extrinsic post is it can be problematic in low volume or narrow shank shoes. Intrinsic posting can solve that problem. Three options include an inverted rearfoot and/or forefoot post, a Blake inverted orthotic and a Kirby Skive. The first option involves inversion in the cast of the forefoot. The Blake inverted cast has an inversion of 10 degrees or more. This can be accomplished through the pour of the cast or virtual positive cast model. The Kirby skive involves inversion within the heel cup. When adding these modifications it is sometimes necessary to add more varus in the device so that a patient can get used to the device.
Other options for PT dysfunction include a medial flange the can be soft or firm. Another approach is to have your patients wear orthotics in high-top shoes or sneakers to gain even more stability and coupling with the ankle.
The contour of the device is important too. In severe flat foot cases there will not only be little or no arch fill but the arch is increased more than the foot presents. A technique to increase the casted or scanned arch height is to dorsiflex the first toe. Finally, a deep heel cup of 25 mm or more can be added to obtain more control. In more severe cases an orthotic with contact above the malleoli may be necessary. A Richie brace can be used if orthotics do not provide enough medical stability.
