Long arm splints are used in a variety of settings for immobilization of both bony and soft tissue injuries to the upper extremities. This type of splint provides immobilization to the elbow and the wrist. As a result, elbow flexion and extension and wrist flexion, extension, forearm supination/pronation can be restricted. Long arm splints are often the initial form of immobilization placed on an injured limb to accommodate soft tissue swelling before more definitive treatment with a cast or surgical fixation.
Long arm splints should fit each patient's anatomy appropriately, without excessive pressure or laxity at any given location of the device. Materials used should contour bony prominences and care should be taken to mold the splint in the desired position of immobilization.
Long arm splints have a variety of indications:
A well functioning long arm splint requires care when obtaining the appropriate supplies. The practitioner can choose between plaster and fiberglass for splinting material. The benefit of plaster as a splint medium is that it conforms more precisely to the patient's anatomy; however, it lacks fatigue strength compared to fiberglass. On the other hand, fiberglass is more durable with higher fatigue resistance; however, it is more difficult to mold and does not mold to a patient's anatomy as closely. Also, fiberglass application often requires the tighter application of a compressive dressing which can cause discomfort to patients if it is not loosened. Of note, fiberglass provides a more consistent appearance on X-Ray than plaster, making fractures potentially easier to visualize.
To efficiently assemble a long arm cast, the practitioner should recruit the help of at least one other person. Have an assistant hold the patient's extremity in the desired position of immobilization while the splint is being created and molded. This can help with accurate placement of materials and minimize impingement of structures that could otherwise need to be adjusted after splint application (e.g., anterior cubital fossa).
Preparation of a long arm cast involves several steps. The practitioner may decide on the width of plaster or fiberglass to use that best fits the patient's anatomy. For adults, this often translates to 3-inch diameter sugar tong and 3 to 4-inch posterior mold material. For pediatrics, 2-inch sugar tong and posterior mold often work well. For plaster and fiberglass, the length of the sugar tong and posterior splint should be pre-measured. With plaster, eight to 10 layers are often used. For fiberglass, most splinting materials come pre-fabricated. Synthetic or cotton web roll should be obtained for padding. Optionally, stockinette can be used for patient comfort as a base layer before splinting. The final overwrap typically is performed with an elastic bandage.
If fiberglass is used, the same techniques can be used, but web roll is not required for overwrapping as long as the fiberglass comes in a synthetic sheath. Additionally, it can increase patient comfort to cut a small margin of fiberglass back from the synthetic wrapping to create a soft end to the splint material. Once the materials are accurately and efficiently applied, the splint is molded to the desired shape to promote continued reduction of the injured structures. Once the fiberglass or plaster hardens, the patient should be instructed on splint care.
As with any splinting technique, there are a few possible complications.
Long arm splints are a valuable tool in the treatment of a variety of upper extremity injuries. This form of splinting can provide excellent immobilization while allowing for swelling that often accompanies acute injuries. Typically, a long arm splint is the initial form of immobilization. It typically is removed, and patients are transitioned into more definitive immobilization such as a cast. The practitioner needs to take time to become familiar with the materials and techniques needed to make a well padded and molded splint that properly positions a patient to maintain a reduction and allow for soft tissue swelling.