What type of cast is appropriate for immobilizing an unstable humeral fracture?

A shoulder spica cast is particularly suitable for immobilizing an unstable humeral fracture because it provides comprehensive support and immobilization to both the shoulder and the upper arm. This type of cast encases the torso and extends around the affected shoulder, limiting movement and allowing the bones to stabilize and heal properly.

Unstable fractures often require enhanced immobilization beyond what standard casts can offer. The shoulder spica cast effectively accomplishes this by not only stabilizing the humerus but also creating a controlled environment that limits any unwanted movement that could complicate healing.

In contrast, other cast types like the short-arm cast or long-arm cast primarily support the forearm without adequately immobilizing the shoulder, leaving the fracture at risk for misalignment and improper healing. Similarly, a hanging-arm cast would not provide the necessary support for an unstable humeral fracture, as it typically only offers gravity-assisted support without full immobilization. Thus, the shoulder spica cast is the most appropriate choice for ensuring proper alignment and healing in cases of unstable humeral fractures.