By Steven W. Cutler

Introduction

Broken casts are a constant nuisance for the patient and are an aggravation for the orthopaedic practitioner. They cost time and money for both. The patient has to call the office to make an appointment, then adjust his schedule, even pay the added expense to have the cast repaired or replaced. This also puts a burden on the office staff since the patient has to be added onto the schedule, the chart pulled, the patient seen, the problem fixed and the transcription done. All this can be avoided if the cast does not fail.

Granted, sometimes the patient is at fault because he or she has abused the cast despite the instructions. It is possible the material was defective or of an inferior product. Or sometimes, the orthopaedic practitioner just doesn't understand the correct use of the material. The first reason for failure, the patient, the orthopaedic practitioner has little control over. Patients just do what they want. Manufacturers have refined their products over the last 30 years to offer a good cast material and, again, the orthopaedic practitioner has no control over that. But the third reason, poor understanding of the material, can be avoided if the orthopaedic practitioner simply understands the material he is using. This he has complete control over. Every box of cast material comes with an instruction sheet that, when followed properly, will result in a good quality casts. It is, therefore, important to not only read the instructions, but also to understand and follow them.

Materials

The materials used today to construct a cast range from plaster of Paris to various types of synthetics. Plaster impregnated gauze has been around for more than 150 years. Inexpensive and easy to mold, it's the standard cast material used today.

However, mechanical limitations have led others to develop a new generation of cast materials, the synthetics. They are fibreglass, polyester and polypropylene/polyester mixture. The substrate is woven to give good handling characteristics and is impregnated with polyurethane pre-polymer that, when dipped in water, will stiffen enough to produce a strong, rigid and light, yet durable cast material.