Today we have a question from a ProLab client and my answer:

QUESTION
Dave is a 73 year old male. His primary complaint is mild pain in his left foot over the 2nd-4th metatarsal heads. He has bilateral heel spurs (about 6mm each) that are currently asymptomatic after corticosteroid injections and custom orthotics about a year ago. He also has a bilateral very prominent base of the 5th metatarsal with significant callus formation bilaterally, greater on the right, that seem to be getting larger with time, but are asymptomatic; the prominence is quite visible laterally but also INFERIORLY in a plantar direction (to a lesser extent than laterally).

My proposed custom orthotic prescription is as follows:

Milled polypropylene shell, semirigid, 20mm heel cup, wide width, minimum cast fill, 2mm medial heel skive bilaterally, bilateral medial flange, standard rearfoot post with 0/0 motion, leather top cover to toes with 3mm Poron under topcover and 1.5mm bilateral heel pads.

My concern is to avoid pressure on the prominent base of the 5th metatarsal bilaterally. The patient’s existing orthotics seem to exert pressure here and encourage callus formation. Is it possible to do a STANDARD OR MAXIMUM CAST FILL for the lateral longitudinal arch and a MINIMUM CAST FILL for the medial longitudinal arch? I’m thinking that a minimum cast fill is necessary for the medial longitudinal arch to reduce plantar fascial tension on the attachment to the medial tubercle of the calcaneus to address the bilateral heel spurs, and, to help to unload the metatarsal heads. But, a minimum cast fill under the lateral longitudinal arch would seem to me to put unnecessary pressure on the base of the 5th metatarsal and accompanying soft tissue enlargement. If this can be done, how do I word this on the order form, and, what would be the potential downside of doing so?

ANSWER

Yes, we can add more expansion to the lateral column and keep the cast fill minimal on the medial arch. I think this is a good idea. In fact, I think it is an excellent prescription and I would only make the following changes:

1. Use vacuum-formed polypropylene rather than milled. This will allow you to add a sweet spot for the prominent fifth metatarsal base.
2. Glue the topcover “heel only” so you can further modify the area under the styloid process (by adding a horseshoe pad for example) if necessary.

ProLab takes a scientific approach with our orthoses by integrating evidence-based medicine into orthotic therapy. Our team of Medical Consultants regularly evaluates the medical literature pertaining to orthotic therapy and biomechanics. ProLab clients are encouraged to contact a Medical Consultant whenever they have questions about an orthotic prescription.