The Square Nail is a solid, intramedullary fixation device designed specifically for the treatment of diaphyseal fractures of the radius and ulna, particularly in adult patients. As its name suggests, the Square Nail features a square or rectangular cross-section, which provides enhanced rotational stability compared to round nails. This mechanical advantage helps maintain alignment during healing, especially in the forearm, where proper rotation and length are critical for functional recovery.

These nails are typically made from stainless steel, and are available in various lengths and diameters to match patient anatomy. They are usually inserted retrograde or antegrade depending on the bone and fracture pattern, and do not require interlocking screws. Instead, fixation relies on press-fit stability and the geometry of the nail.

Square Nails are a cost-effective, minimally invasive alternative to plating in select cases, especially in resource-limited settings.