Long Arm Vs Short Arm Fiberglass Cast for Treatment of Displaced Distal Radius Fractures

The most common type of fracture in pediatric patients is the distal third forearm fracture,
with over 600,000 cases in the in the United States each year. Traditionally long arm casts
have been used for displaced distal forearm fractures, but it may be the case that short arm
casts are sufficient. Three RCTs (Randomized Control Trials) have been performed comparing
the efficacy of plaster short and long arm casts for displaced distal forearm fractures;
these studies have shown no significant difference in angulation or displacement. If short
and long arm casts offer comparable stability, the short arm version would likely be
desirable as patient satisfaction and cost effectiveness are improved with short arm casts.

Despite the results of three well-executed RCTs, it is still common practice for long arm
casts to be applied for distal forearm fractures. Many surgeons continue to recommend that
their residents apply long arm casts for all displaced forearm fractures, including distal
third fractures. At NYP (New York Presbyterian) Cornell and NYP Queens, residents routinely
apply long arm casts for all forearm fractures.

Long arm casts are more likely to result in elbow stiffness, although this is often a
temporary complication. Long arm casts also require more material and take longer to apply or
remove, potentially leading to higher treatment costs. Additionally, when a longer cast is
worn there is a larger distance where a cast burn could occur. Skin irritation, particularly
at the cubital fossa, is likely more common with a long arm cast, and they are overall less
comfortable, due to elbow restriction and a heavier weight.

Short arm casts that are well molded to the arm's contours have been shown to control forearm
supination and pronation. A low cast index has been shown to significantly increase the rate
of fracture redisplacement. The cast index determines the quality of cast molding, and is
measured by dividing the sagittal width of the cast by the coronal width. Substantial changes
in cast angulation have been attributed to poor cast-molding and a low cast index. The
results suggested that short arm casts when appropriately molded can be effective in treating
fractures of the distal third of the forearm.

If short arm casts are equivalent in providing stability for distal third forearm fractures,
providers should be using them preferentially to avoid the potential complications of elbow
stiffness, cast burn, skin irritation, and patient dissatisfaction. However, surgeons persist
with using long arm casts. Rationale for the persistent use of long arm cast is believed to
include anecdotal concerns of residents placing inadequate short arm casts, leading to an
increased risk for translation or angulation requiring recasting.

Previous RCTs, however, do not provide clear recommendations, merely demonstrating that
treatment using short and long arm casts lead to similar outcomes. Additionally, these past
RCTs have limitations. Previous studies were conducted with plaster casts and could not
extend their findings to other casting material. Valving techniques were also not noted in
these studies; it is unclear whether or not casts were bivalved, which is currently the
standard of care in the United States. These previous studies also randomized patients to
short or long arm cast prior to cast application. As a result, it is possible that when long
arm casts were applied the portion of cast overlying the fracture site was not molded as
carefully as for short arm casts. Previous studies commented on cast index, but it was not
clear whether residents were trained in ideal cast application and molding prior to study
initiation. Finally, the outcome measures used in previous studies were an arbitrary loss in
angulation or translation, instead of a focus on whether the fracture slipped sufficiently to
change the treatment required (need for cast wedging, repeat reduction and casting, or
surgical intervention).

The aim of the study is to determine by multicenter randomized controlled trial whether short
arm fiberglass casts are as effective as long arm casts for immobilizing displaced pediatric
distal third forearm fractures that have undergone closed reduction.

Inclusion Criteria:

Patients 4-12 years of age

- Displaced distal third forearm fracture (physeal, metaphyseal, meta-diaphyseal)
requiring closed reduction

- Displacement must be: For children 4-9: angulation >30 degrees and/or 100% translation
on either AP (anteroposterior) or lateral view. For children 10-12: angulation > 15
degrees and/or >50% translation on either AP or lateral view

Exclusion Criteria:

- Patients undergoing additional orthopedic procedures at the time closed reduction of
distal arm fracture

- Patient with a presenting open fracture

- A known pathologic fracture

- Patient with a refracture through pre-existing fracture lines

- Patients with compartment syndrome or neuropathy