Reprinted with permission from Injury, Int. J. Care Injured (2008), 39, 368-370.

Summary
Introduction: Splitting of a plaster cast is frequently required to accommodate post-operative limb swelling. Oscillating saws are often used, but can cause injury and distress and cannot be used when the plaster is drying. At these times, plaster shears are used. A safe technique is described, which safely divides drying plaster using a sharp scalpel.
Method: Plaster casts were applied to 40 modelling balloons, consisting of one roll of 3-inch and one roll of 4-inch plaster. The balloons had either two or four wool layers beneath the plaster. Ten from each group were split using our technique and 10 from each group were split with plaster shears. The number of balloons that were not burst during the splitting process was recorded.

Results: Of the 20 plasters split with a scalpel, all of the balloons remained inflated. The balloons underneath two of the plasters with two layers of wool that were split using plaster shears burst during splitting. When the plasters split with a scalpel were dry, they could be opened easily using cast spreaders and the wool cut with scissors without the balloons bursting.

Conclusion: This is a safe and simple technique for splitting a drying plaster without the need for extra materials. It allows easy completion of the release with scissors alone should swelling of the soft tissues become excessive. The need for plaster shears or oscillating saws with the potential trauma associated with these established methods is eliminated.

Introduction

Limb swelling following closed reduction of a fracture or open limb surgery is common, although subsequent development of compartment syndrome is fortunately rare. However, following the application of a plaster, an otherwise troublesome but safe swelling has the potential to turn disastrous due to the rigidity of the plaster cylinder. In these cases, the plaster needs to be promptly split to skin and then opened to relieve limb pressure. Previous work has shown that in order to significantly reduce the pressure in a limb, the plaster and wool should be split and separated along the length of the limb (Henderson, Wallace, & Bowker, 1986). This has been further quantified in a study on dogs by Garfin, Mubarak, Evans, Hargens and Akeson (1981) who showed that casts were found to restrict compartment volume by approximately 40%, with the most significant reduction in pressures recorded after the cast was cut and spread. After cutting the underlying wool, the limb pressure dropped by a further 10% to 20% (Nunez, & Arnander, 2006). Backslabs have been shown to be no better than full plasters in accommodating an increase in internal pressure (Younger, Curran, & McQueen, 1990). Plasters are frequently removed using an oscillating saw and these have been shown to cause injuries (Ansari, SNNarup, Ghani, & Tovey, 1998). The use of oscillating saws can also be distressing to young children. It is generally accepted that an oscillating saw cannot be used efficiently while a plaster is drying and this state persists for more than 12 hours. If a plaster needs to be split in this time. plaster shears are used.

A technique for splitting a damp plaster with a scalpel has been previously described, but requires placing a length of plastic tubing in between the wool and plaster and cutting through the plaster into the tubing (Garfin et al., 1981). It was traditionally stated by older surgeons that splitting a drying plaster with a scalpel with no plastic is safe providing the wool is thick. This is based on the observation that drying plaster is easily cut by a fresh scalpel blade and thick wool is not. To test the truth of this claim, a test was set up.