We now go into more detail on the internal fixation system with plates.

Before talking about shapes (straight, T, L, etc.), we need to understand how a plate acts mechanically on the bone. This is called the mechanical system of the plate.

Indeed, a bone plate is not just a simple piece of metal screwed onto a bone: it is a stabilization device designed to transmit and distribute the forces exerted on the skeleton during healing.

There are three main types of plates:

1. Simple plates
2. Dynamic compression plates (DCP)
3. Locked plates
4. Combined plates

Each plate model generally exists in several physical variants, such as:

• Length: number of holes, thus the number of possible screws.
• Thickness: mechanical resistance (thicker → more rigid).
• Width: mechanical resistance and adaptation to the diameter of the bone.
• Hole diameter: determines the type and size of compatible screws.

As for screws, the main types are:

• Cortical screws (self-tapping or not)
• Cancellous bone screws
• Locked screws

They also come in several variants:

• Length: adapted to bone thickness.
• Diameter: depends on bone size and plate type.
• Drive or head: cruciform, hexagonal, stardrive, etc. 

Each system corresponds to a different surgical philosophy, adapted to a type of fracture and a desired level of stability.

These different systems are developed in the following chapters.

Illustration :