**2.6 Working length of plate**

In locking plates, the distance between the proximal and distal screw in closest proximity to the fracture is defined as the "working length" of the plate (**Figure 2**). If a plate is compressed against the bone (dynamic compression plate), the working length is the distance between the bone ends of the fracture span by the plate (**Figure 2**). A correlation between plate working length and stiffness of the construct, plate strain, and cyclic fatigue properties of the plate has been shown [5, 7–10]. Another fundamental aspect in high-strain fracture management (e.g., simple transverse fractures) is load sharing between the stabilized bone and the plate; not addressing this aspect in osteosynthesis increases the risk of cyclic fatigue and early failure of the plate.

#### **Figure 2.**

*Illustration of the concept of working length of the plate. The working length of a bridging plate is defined by the type of plate (LCP vs DCP) and the interaction of the plate with the bone. (A) A dynamic compression plate is held to the bone by non-locking screws. When bending occurs, the working length is the distance between the bone ends of the fracture span by the plate. (B) The locking plate spans the same gap, but because the plate is not in direct contact with the bone, the distance between the nearest proximal and distal screw to the fracture line is defined as the working length.*

*Biomechanical Basis of Bone Fracture and Fracture Osteosynthesis in Small Animals DOI: http://dx.doi.org/10.5772/intechopen.112777*

Also, the plate length influences the screw loading. For a given amount of bending moment, a longer plate produces markedly less pull-out force than a short plate due to an improvement of the working leverage for the screws.

The effective application of plate length is another concept. The farthest screws determine the effective usage of plate length and contribute to fracture gap stability. A long plate produces markedly less pull-out force than a short plate.
