First published in 1852 by a military surgeon named Antonius Mathijsen [2], plaster (of-Paris) has been used for over a century in order to immobilize fractures. It was the only true rigid splinting material available until the advent of fiberglass in 1987. More recently, prefabricated splints such as Ortho-Glass are available. This post focuses on the traditional method to forming a splint from plaster or fiberglass.

Given the layering and formed paste, plaster can be more difficult to apply. However, it is more malleable. Fiberglass, while less flexible, hardens quickly, is easier to apply, and is lightweight [3]. The newer prefabricated splints such as Ortho-Glass contain fiberglass and are pre-padded. Unlike traditional plaster and fiberglass, these pre-padded fiberglass splints require only a minimal amount of cool water to activate. The selection of splint material will depend on provider preference and institutional availability.

Ortho-Glass® splint material (Photo Credit: William Denq)

The use of a stockinette can be useful in protecting the skin from the sharp edges of splinting material. It prevents chafing and helps to maintain the shape of the splint. However, if the stockinette is too loose or the wrong size, the material can collect together and create pressure points, which increase the risk of skin ulceration. If the stockinette gets wet, it can cause skin maceration. Typically, a stockinette is not required for a simple splint – padding is enough to protect the skin.

Stockinette (Photo Credit: William Denq)

Padding is required for both plaster and fiberglass media. It provides a comfortable medium between the skin and rigid splint, while also preventing skin maceration [4]. Padding, like the rigid splinting material, is categorized by its width, usually 3, 4, 5, or 6 inches.

Soft padding (Photo Credit: William Denq)

Evaluate for bony prominences, and adequately pad these areas, which are prone to forming pressure sores. Examples include the olecranon, malleoli, and calcaneus [2]. Applying additional strips of padding to these areas avert the need to place an additional circumferential wrap.

Water temperature affects how fast the splinting material hardens [4]. If the water is warmer, the material will harden faster. However, the quicker the material hardens, the greater potential for a serious burn. Never use warm or hot water for plaster. Utilize cool water with fiberglass as it inherently hardens faster than plaster. Tepid water should be be used to activate plaster. Be sure to change the water you use after each splint application because the residual splint material can accelerate the activating and hardening process [2].

Use tepid or cold water for plaster or fiberglass, respectively. (Photo Credit: William Denq)

If splinting fingers or toes, ensure padding is placed between fingers/toes to prevent maceration. If splinting the forearm and the padding needs to traverse the thumb, create a defect in the padding to stick the thumb through.

Application of stockinette and overlying padding (Photo Credit: Caleb Sunde)

If using plaster, submerge the layers in tepid water until the bubbling stops. This signals the complete saturation of the material [3]. If using fiberglass, submerge the layers in cool water until the bubbling stops. Prefabricated splints such as Ortho-Glass should not be submerged as it only requires a minimal amount of cool water to activate the material.

The purpose of applying water to a splint material is to activate it. Doing so will cause an exothermic reaction while the material hardens. Because burns have been reported, use cooler water (as opposed to hot water), and apply generous padding. Wring out as much water as possible while still maintaining the plate-like integrity of the splint material. Place the splint on a hard surface or several layers of your pre-cut padding to smooth out any formed wrinkles.

Activating the splint by submerging in tepid water (Photo Credit: William Denq)

While keeping the extremity in its desired position, conform the material to the extremity with the palm. Fingers can create indentations and unintentional pressure points that may result in skin breakdown [4]. An assistant may be used to help stabilize the splint material onto the affected limb. To avoid accidental soft tissue damage or discomfort from the sharp ends of plaster and fiberglass, fold the edge over on itself. In general, plaster hardens in 5-10 minutes and fiberglass in 3-4 minutes.

Do NOT rest the affected extremity with a forming splint on a surface such as a pillow or table as it could trap the exothermic reaction generated and result in a burn [2].

Application of the splint over stockinette and padding (Photo Credit: Caleb Sunde)

The elastic bandage should be wrapped onto the affected extremity in a distal to proximal direction. This theoretically helps with venous return and reduces subsequent swelling from an acute injury [5]. Although the bandage application helps to conform the hardening splint material to its desired position, excessively tight application (in an effort to reduce swelling and mold the splint) may instead result in compartment syndrome.

Application of the elastic bandage should be in a distal to proximal fashion. (Photo Credit: Caleb Sunde)

After the splint application, the procedure is not yet complete.

1. Check and document all the pulses in the region. If the occlusive dressing prevents you from being able to document these pulses. The next best assessment is to check and document the distal capillary refill and sensation exam.
2. Check the range of motion of the unaffected joints to ensure that the splint does not interfere with their movement [1].