Rohadur was one of the most widely used rigid foot orthotic shell materials by foot orthotic laboratories in the 70’s and 80’s. It is no longer available. It did set a standard for foot orthotic materials as its characteristics made it so useful. It came in various thicknesses and was easy to heat mold to the positive model of the foot. It was also easy for the clinician to reheat and spot mold the device. It could be reheated multiple times without becoming brittle. It was easy to grind. It did have a reputation of cracking under certain load conditions (eg jumping on it from a height).
The trademark for Rohadur was registered at the USPTO in 1957 by Rohm GmbH based in Darmstadt, Germany and it expired in 1998. The description in the trademark was “organic glass (artificial resin) in form of foils (sheets), plates, blocks, bars and tubes.“
Rohadur is an acrylic material that was made from a polymethyl methacrylate with acrylonitrile cross-linking polymer. It had a light orange or amber color. The pre-cursor material, acrylonitrile was subsequently found to be a low-level carcinogen and Rohm GmbH ceased production of it in 1989. While it was possibly carcinogenic during the materials manufacturing process, it was not carcinogenic to patients who were using the foot orthotics made from Rohadur in their shoes. It is also possible that the carcinogenic material may have been released in the dust when grinding or with overheating, but that is not clear.
Acrylonitrile is a highly flammable material that is toxic at low doses. It is classified as a Class 2B carcinogen (which is possibly carcinogenic) by the International Agency for Research on Cancer (IARC). Workers that have been exposed to higher levels of airborne acrylonitrile have been reported as having higher rates of lung cancer.
Following the cessation of production of Rohadur a number of materials were used to find suitable replacements such as other acrylics (eg Polydur), graphite composites (eg TL-61, TL-2100) and the polyolefins such as polyethylene (eg subortholene) and polypropylene. The movement is now away from those materials towards 3d printing of foot orthotics.
As supplies of Rohadur became limited and foot orthotic labs were running out, Langer Labs purchased large quantities to keep their product line going. They did eventually run out:
Other Foot Orthotic Shell Materials:
| Carbon Fibre Composites | Ethylene-vinyl acetate (EVA) | Evazote | Plastazote | Polypropylene |
| Rohadur | Polyethylene | Polyoxymethylene | Subortholene | Thermoplastic Elastomers (TPE) |
| Additive |
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A Rohadur orthotic was a pleasure to make for patients. it looked beautiful and felt smooth and almost comforting to hold. I enjoyed making these for my patients and I am sorry no replacement has been found to be as nice to use.